From sjnoll@ix.netcom.com Tue Mar 12 06:54:30 1996 Date: Tue, 12 Mar 1996 06:49:18 -0800 Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit From: sjnoll@ix.netcom.com Subject: VTP1188S Specs, Responsivity, Capacitance, Photodiode speed, Reverse Bias. To: aballen@COLBY.EDU, daveaa1a@pcix.com, jmoss@berlioz.nsc.com, kent.e.britain@tek.com, nc1k@pcix.com X-Mailer: SPRY Mail Version: 04.10.06.22 Content-Length: 2738 Status: RO X-Lines: 61 Here are the important specs for the EG&G Vactec VTP1188S Silicon Photodiode. Sorry I hadn't published them with the paper! min typ max units Id Dark Current @ Vr = 100 mV 3 30 nA Cj Junction Capacitance @ Vr = 0 0.3 nF Peak Responsivity wavelength 925 nm Responsivity @ Peak 0.55 A/W AA Active Area 11 sq-mm I chose this device because: 1) It's active area (AA) is not too small. This is so you can have a reasonable chance of focusing the most amount of light on it with the kind of mechanics and optics that an amateur can afford. BUT - Large active area = large capacitance = slow speed. No problem here for audio, etc., but for video you want to use the smallest active area you can live with. 2) It's dark current is not unreasonable. This will translate to noise which will translate to distance achievable. It also has a nice molded lens. It's cheap and available in onesy-twosies. Now, in case you didn't know, the sensitivity "Responsivity" (Amps/Watt) of all silicon devices is about the same, as is the spectral response curve. You can make small sensitivity alterations through the manufacturing process - like use thicker silicon to increase IR response, apply Anti-Reflective (AR) coatings, use Quartz windows for UV, but the results are not what we would call really significant. What I'm getting at is you aren't going to find a "really hot" photodiode with a 10 A/W sensitivity. There's a theoretical limit to the curve, and that's that. (Avalanche photodiodes are another story - but not as good of one as you'd like to hear.) Now - to improve the speed I already mentioned reducing the AA and thus the capacitance. There are also circuit techniques - bootstrapping is one. In fact, the issue of Sensors Magazine that arrive here yesterday has a good article on just that. How timely! And don't forget Vr - Reverse Bias. Applying reverse bias widens the junction and thus reduces the capacitance. This is SOP, Standard Operating Procedure. You can apply a reverse bias up to the Vbr - Breakdown Voltage - of the device. Vbr is not spec'ed for the VTP1188S - which is real stupid. EG&G says it's typically 140V for the VTP series, which seems really high to me. However, the reduction in capacitance begins to level off around 5V, where a 70% reduction in capacitance has been achieved - so you can see it's well worth it for high speed operation. Reverse bias does increase noise. By the way. Reverse bias means connecting a positive voltage to the cathode, or a negative voltage to the anode - it doesn't matter which way you hook it up. Got to go to work. 73, Steve J. Noll | Ventura CA | WA6EJO | IEEE | AVS | sjnoll@ix.netcom.com From aballen@COLBY.EDU Wed Mar 13 00:33:02 1996 X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Wed, 13 Mar 1996 08:30:48 +0000 To: sjnoll@ix.netcom.com From: "Art Allen, KY1K" Subject: Re: Rifle Scopes. Initial Signal Aquisition. Bias Polarity. Cc: daveaa1a@pcix.com, nc1k@pcix.com, kent.e.britain@tek.com, lmcpegr@langate.lmc.ericsson.se, jmoss@berlioz.nsc.com Content-Length: 9700 X-Lines: 188 Status: RO At 09:10 PM 3/12/96 -0800, you wrote: >Yo Laser Dudes: > >Here's how I've done Initial Signal Aquisition for all my shots up thru >48 miles. > >First, I've always mounted a rifle scope on the laser. One good thing >about a HeNe is you've got a big hunk of something to mount to, huh? >Now it would be nice to have a $250 rifle scope with big, bright optics, >but I'm just not that kinda guy. I think mine are $7.96 Kmart Blue >Light Specials. I've seen that a rifle scope is >very helpful, but it is not near all you hoped for (at least not for >long shots). Of course, at night it's so dim as to be very very >difficult to use. Next, they are very low power instruments. They're >supposed to be. I'll always remember being out past Bakersfield CA, >looking back towards Mount Pinos - about the best mountaintop in So >California (8831' before the last earthquake.) Before I went on the >road I figured that I'd just set up while there was still daylight and >get the peak in sight and get to work. WRONG! From 50 miles there >ain't no peak - just a faint, mushy, undefined ridge of grey stretching >for 100 miles. It looks so different from so far away! Rifle scope & >small telescope were no help. Let me interrupt to say that long ago I >modified a rifle scope by adding LED illuminated cross hairs. That >didn't help at all and I removed it. Another problem is at any real >distance the width of the crosshair hairs totally obliterates the >target! I always use rifle scopes with cross hairs to get as close as >possible - it's just dumb luck if that's close enough - in fact, it's >never been yet for me. And I'll bet in never will be with 0.07 mrad >divergence. Yes, u put it in words alot better than I did Steve! 'Faint, mushey and undefined'...no contrast, blurrey... No fun hi hi. OK, the newer pistol scopes (big $$) use this LED illumination of the cross hairs too. I havent tried them at night, but it might actually be worse. Dave, how does your scope seem to work for shorter/medium distances??? Should I try this method, or look for something different for longer ranges. Along this subject, I had a brainstorm yesterday.....more later... > >When we got positioned as well as we could guess (with aid of a compass) >one end would shine a handheld spotlight, or even car headlights, in the >suspected direction. These will work for several 10's of miles. For >longer shots a _good_camera photoflash is used. Even better - I got a >helical Xenon flashlamp and mounted it in the focus of an Edmund 18" >spun aluminum parabolic solar reflector. The flashlamp supply is a >double-flash type, "Pop pop pause pop pop, etc." Way bright. When >each end of the shot saw the light they then had somthing to aim at. >This was bright enough to see through the rifle scopes and to center the >cross hairs on. You're real close and maybe even are seeing flashes of >red. For the next step we used a lower frequency for liason. One end >would scan their laser very slowly back & forth and up & down with the >micrometer screws. The other end would give a yell when they saw a red >flash. Then it was on to fine tuning over a much smaller sweep at a >slower rate. The first yells were never quick enough to stop that tiny >beam. I think the 48 mile shot maybe took 1/2 hour for this. Now when >one end is lined up the other end has a _real_ bright light to get their >cross hairs on. By the way - 2 mW HeNe is plenty bright at 48 miles. >It was suprisingly visible in full daylight, although pink, over my >first shot of 15 miles. > >The Arizona guys used the flashlamp method. They said that handheld >spotlights worked for them for up to 100 miles. Beyond that Xenon >flashlamps were necessary. OK, I thought I recalled the AZ guys had mixed results with the flashlamp method, they thought it was due to the non-monocromatic output.. Since it should have alot of IR in it, I would think this would be a great method for ir rx pointing..U could align the rx based on the 'pop' heard in the speaker of the rx, u would know u had the rx aligned. If the laser table was mounted to the top of the rx box, then your tx would probably be within a couple degrees too....By aligning the rx FIRST, u could simply transmit the rx output back on the liason freq in real time, and the guys moving the laser tx around would have instant feedback.... Dave commented earlier that he could 'hear' the strobes on airplanes, even after they disspeared visually... since IR propagates so much easier then visable, I think its fair to say that Dave already demonstrated this rx alignmnet technique. OK, I was about to ask u guys how bright the laser was...We have plans to do a shakedown 100 km shot, and its good to hear that a 2 mw hene is 'plenty visable'. Tnx again Steve.... Dave, how bright is the 670 nm diode at 12 miles, would u guess it would be visable at 100 km ????? > >Other's have suggested a surveyor's transit and sighting off of the >North star to get the exact bearing. OK, barb is an astronomy/math major...North star is only good for 2 degrees accuracy, and without buying an expensive comm'l transit, u probably have a little added error in there from your homebrew transit.... I'm not sure about this.. > >Hey guys, think about this... The ideal "rifle" scope might be a 6" to >10" Questar or Celestron with crosshairs? Pipe your laser through it >for a TX collimator and use it for receive antenna too. It really >should be the cat's meow. Pop different wavelength lasers into the >eyepiece tube and QSY quicker than you can say "Ay Double Cross El"! >Put a night vision image intensifier thingy in the eyepiece for aiming >at IR lasers. (Send money - I'll tell you how well it worked.) Funny should mention Celestron telescopes...we used a 9 inch one last year to do some star gazing....They would make a fine RX but NOT stable enuff for any laser tx... My first laser rx was a simple Crap Shack IR photransistor with a 741 op amp. We domonstrated that rx could hear a 2 mw 2.2 mrad laser at 1km (hence making it acceptable for vhf contest laser q's. Later, after the star gazing session, we mounted it about half an inch back from an eyepiece and I was able to hear an LED free running osc at about 220 feet using it... Not bad for a 2 dollar rx. >>From the technique I just described you can see why I've favored visible >lasers - it's kinda important to the whole process. > >"Variable Bias and Polarity" Whoa - don't switch the polarity on a >photodiode! Unless you gotta really big series resistor it's goodby >photodiode if you forward bias it! If yours seem less sensitive now >than before, then.... >Also, variable bias shouldn't do you any good, except maybe add some pot >noise to the photocurrent. I suppose you could try "tuning" a tradeoff >between speed and dark current noise. > >Yes, the AVS is for the American Vacuum Society. I got into vacuum >science in my last job. I like it. Wish I did it in current job. I >homebrew-computer-controlled (Forth) a two-target load-locked sputtering >machine, artificial intelligence, moving-graphics interface - fun stuff. >DC & RF, Au, Pt, Pd, W, TiW, Al, Cu, SiO2, targets. Turbo and cryo >pumps. Residual Gas Analyzer, no less. I love things that glow in the >dark - Argon plasmas and the warm glow of an Ion gauge - it doesn't get >better than that - Hi hi! OK, Steve, I was a plasma systems engineering tech. I spec'l'd in plasma etch/dep systems... Most of the stuff i had direct exposure to was roots blowers and mechanical roughing pumps. We all had to do safety tho, so everyone in the equipment engineering group cross trained like mad, just in case of an emergenncy in the fab area (toxic gas pumping, purge systems for pyroforic and toxic gasses, safe shutdown) of ALL fab equipment (not just the stuff in our own area). Plasma is certainly neat and I love the sound that roots blowers make...like music to my ears. >73, > >Steve J. Noll | Ventura CA | WA6EJO | IEEE | AVS | sjnoll@ix.netcom.com > > Everyone, please take a few minutes to drop Per, sm0dfp/ve2 a line. Per is from the vhf weak signal group, but saw my laser inquire and hollered at me via email. I would normally snip alot of this, but, Per is new, and one of his major concerns is 'aiming'.. How timely, so I thought I would bounce the whole message up his way. Per lives in Montreal and is interested in basic laser communication. -------------------------------------------------------------------------- OK, now for my brainstorm, has to do with aiming, simple and cheap methods..... We live in the country, at the end of a 600 foot long driveway. When barb came home last night, I just happened to be looking out the window as her headlights hit the double pane windows on the way down the drive. What I saw was the multiple refractions from each layer of glass, a whole line of dots on the glass when the car was at an angle realtive to the windows...but, when the car was at right angles to the windows, all the dots were lined up so that they looked like a single dot... I'm wondering if this property can be used for sighting/aiming of laser tx's?? Certainly, if u line up multiple layers of glass and then sight thru them, it would be relatively impervious to problems mentioned earlier with rifle scopes... And its cheep....probably pretty stable mechanically too (dave mentioned he had to recalibrate his scope, and now carries it in a padded box). Maybe its not such a brainstorm after all...ideas/thoughts.... Hey, its 2:50 AM local time here, Im gona shut down and get some sleep...Bye, Art.... From jmoss Mon Mar 11 17:42:14 1996 Date: Mon, 11 Mar 96 17:40:43 PST From: jmoss (Jim Moss) To: aballen@COLBY.EDU Subject: Re: LOS info neeeded (NE/Canada only) Cc: jmoss Content-Type: X-sun-attachment Status: RO X-Lines: 57 Content-Length: 2466 ---------- X-Sun-Data-Type: text X-Sun-Data-Description: text X-Sun-Data-Name: text X-Sun-Content-Lines: 4 X-Sun-Content-Length: 87 here's what's going on. I think. Haven't tried attachements before. We'll see. Jim ---------- X-Sun-Data-Type: default X-Sun-Data-Description: default X-Sun-Data-Name: laser.txt X-Sun-Content-Lines: 41 X-Sun-Content-Length: 2099 WB9AJZ - N5XSA Laser Status WB9AJZ system: TX: 670nM, 5mW laser diode (pointer pen) MODULATION: 800 Hz squarewave full on/off keying. Bursts controlled by a keyer to effect morse code at 800 Hz. RX: simple phototransistor, with 2 stages of AC audio amplification. Audio out to headphones or DSP-59+ filter system. 8" parabolic mirror available as needed. Aiming: Visually, with camera tripod and "fine" tuning jig. Jig allows better than < .5 mR positioning in Az and El. DX: easily at 1 mile, QSO'd off a gaussean ring. Trouble with pointing! With NO RX lenses or mirrors. N5XSA system: TX 670nM, 5mW laser diode MODULATION: 40 or 44 KHZ (I don't remember) carrier, modulated with voice. RX: photo diode and opamp system to audio amp/speaker. Aiming: Visually, with camera tripod. DX: very rough at 1 mile. Pointing issues. But... very distorted audio due to wind/temp/??? Lucky to complete. Kinda like meteor bursts of clarity. Others in the area interested include AJ6T (Walt) and one other I can't remember. I met K6LMN (Roger) over the weekend at a WSWSS meeting. He proposed that we set a minimum standard so that if we should meet up, we can make Q's! His suggestion was simple audio such as my system. He has made Q's in the past but has been inactive. He will get going again based on what he has heard from me. Roger is in the LA area. WA6EJO, I have heard of him, but he lives down in the LA area in Ventura. Roger and he used to do somethings together. Think he has lost interest. Future: plan to extend range. continue with 800Hz CW approach for now. Do some research into distortion effects thru the air. (books and experiments) Consider that aiming seems to be a MAJOR issue at short distance (will improve farther out, based on gaussean spreading)... look at high data rates to minimize time on target. Like sweep across target with high data rates to get a hit. Either mechanical or electronic sweeping. IRDA standards for 100KB or 1-4MB ? Who knows.. Jim WB9AJZ/6 From aballen@COLBY.EDU Wed Mar 13 11:45:43 1996 X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Wed, 13 Mar 1996 19:42:34 +0000 To: sjnoll@ix.netcom.com, daveaa1a@pcix.com, kent.e.britain@tek.com, jmoss@berlioz.nsc.com, aballen@host-04.COLBY.EDU From: "Art Allen, KY1K" Subject: Re: Mt Royal Content-Length: 3994 X-Lines: 96 Status: RO >To: lmcpegr@langate.lmc.ericsson.se >From: "Art Allen, KY1K" >Subject: Re: Mt Royal > >At 10:10 AM 3/13/96 -0500, you wrote: >> Hi Art, >> >> Some more reliable information on the Mount Royal sites: >> >> Mt Royal lookout: >> >> 45.30.15 North 73.35.15 West. The peak is 218 Meters and the lookout >> is at 195-200 Meters facing ESE. >> >> Mt Royal summit: >> >> 45.29.35 North 73.36.31 West. The road circle the summit at 205 >> Meters. The observation area at 200 Meters +/-3 Meters is facing SE >> and Mt Equinox is visible. >> >> My QTH at 145 Meters has an obstruction (house) in 170 degrees, some >> trees at 175 degrees and no obstruction in 180. It seems impossible to >> work from my QTH at light anyway. >> >> >> I need some info on how to make a receiver, did I understand correctly >> that someone had kits with hard-to-get parts and drawings for the rest >> of the rx. >> >> >> 73 de Per -ve2/sm0dfp >> > > >Hey Per, > >MANY THANKS for the info...I promise my first born son to you (just kidding)... > >OK, sounds like the peak or the summit would be FB for a laser Q to Mt Equinox.... This is almost to good to be true. > >OK, anyone in the group will be happy to advise u on laser rx...but, I suggest that you examine your goals and needs before building, also keeping in mind that you will have limited time too..... I'm not sure whether you will take your gear with you back to SM when u go either...if it is going to be left here, you might want to go with the lower cost approach. But, if u have clear air in SM, u might want to spend the extra time/$$ to build a higher sensitive rx.... > >Not sure of your situation there...the complex rx will cost you much more $$ and will take longer to build and parts probably arent available locally (mail order for them).... > >The inexpensive rx is much less sensitive, but uses a 741 op amp and a darlington phototransistor....simple, easy, quick and cheep...not so sensitive tho. I have one that is assembeled and tested, I'll send it to u if this will help. > >I dont think anyone in the group has a kit available, although most of us have parts, even extra parts that we might give up for a worthy cause hi hi. > >Regardless of the type of rx u build, stray light will be a problem for u..U live in downtown Montreal and those big lights u see as you look to the south will all provide qrm. I suggest that you use small active area light sensors and that u use only fair/good quality glass/pyrex lenses (avoid fresnel lenses). The reason being that more precise light gathering optics will minimize the ammount of stray light that will fall on the detector.... My guess is that electronic processing of the rx output will be needed too, a filter to cut off the 60 Hz QRM from those city lights will be a big help. > >I have researched alot for commercal laser rx and gear, no one makes it, not even Downeast Microwave.... It's 'build your own', or else.... > >You might also mention what your job is, and what facilities you have available?? Machine shop? Optical test bench, University of Montreal technical support...and that sort of thing. Also, do you have alot of spare time...this is actually a time consuming mode, so your spare time might impact the type of system u want to put together..... > >Fill me in a little, and I'll be happy to advise and scrounge parts for u... > >Also, can u receive GIF files??? I am getting some hard copy of technical material and can scan it and send it as a GIF file if u can receive it, I do need to ask the autor, but he is a member of the group hi hi.. > >Also, do u have WWW accesss, or just email?? > >It sounds like u got the email regarding the aiming discussion I sent you, I cant stress enough that aiming the tx will be the BIG problem! > >Send comments to the entire group Per....everyone will be happy to help! > >GL...Art.... > > From aballen@COLBY.EDU Thu Mar 14 09:20:03 1996 X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Thu, 14 Mar 1996 17:17:28 +0000 To: sjnoll@ix.netcom.com From: "Art Allen, KY1K" Subject: deep thoughts... Cc: kent.e.britain@tek.com, nc1k@pcix.com, lmcpegr@langate.lmc.ericsson.se, daveaa1a@pcix.com, jmoss@berlioz.nsc.com Content-Length: 12623 X-Lines: 266 Status: RO ------------DANGER DANGER, uncontrolled rambling verbage follows------------ ----------------------Proceed at your own risk------------------------------ OK, you guys have really done it now.... We (barb and I) had kinda safely concluded that aiming was a BIG problem, and we had gone into a semi stable 'low maintenance mode'... Well, she came home yesterday and looked at some of the latest mail here and commented that the group had 'gotten me all stirred up' and then commented that it 'looks like we need to dust off the laser rigs'!! SO BE IT! Hey, u all have lit a flame under my tail, and I thank you for it. I havent really thought this much about laser qso's for years.... It's all your fault!! ------------------------------------------------------------------------ Dave- Got the technical material yesterday, GOOD STUFF. I thank you for sending it...it is truely an excellent starting place. Im thinking Per needs to have it, I have asked him whether he can receive it via the internet... Thankyou for sending it !!! ---------------------------------------------------------------------------- Steve- An excellent write up, wow, just what we need. And, all in one document too!!!! Can u publish it and distribute it, or did u give up the copyright when u submitted it for publication??? I'm a little saddened that u didnt give any clues as to how wavelength of the tx affects the range - at this point we probably need it, but I understand why u didnt do it - adding mia and rayleigh into that formula (which are wavelength dependant) make it a real bitch to solve... And, would totally scare the daylights out of someone with only 'typical' math skills! Incidently, the computer program we use takes into account for the lambda of the tx and the bandwidth of the rx... As i said in a previous writing, we have a workable HP programmable calculator version (which I wrote) and a PC version, which was written by Barbs brother (the programmer), with our collaboration. That range formula changes RADICALLY when u consider bandwidth and lambda of the tx! The pc version solves for any variable.... but the HP calc version only solves for 'range'... ----------------------------------------------------------------------- group- Has anyone thought about a 'free-space laser communication' homepage on the WWW?? With my new provider, we get a big cost reduction in our internet, and I spent some time on the WWW the other day. I couldnt find anything like it... Perhaps we could even put the advanced range formula on line and let people plug in values while online. Certainly, if possible, we would want steves paper online. Barb writes and maintains the home page for the colby college book store and as such, she knows html. Colby now allows its users to have homepages, so the facilities are there.. I suspect that even if Colby didnt allow personal WWW pages, that obtaining a laser homepage would not be a problem, because that would be 'academic' in nature and thats what Colby is about.. Any ideas ??? -------------------------------------------------------------------------- group, esp'lly steve- OK, regarding the write up Steve.. Our PD rx uses an OPA111 Burr Brown chip with 1 gig ohm feedback resistors. At the time I bought the OPA111, it was about the only chip on the market with a low input bias current, and it was only available in a ceramic package and it wasn't cheep (hi hi). I bought low noise high temp stability feed back resistors too... I asembeled it on a copper base and enclosed it totally by soldering a copper shell over the electronics. Put it together in the kitchen of our old apartment on a makeshift antistatic bench on the counter.. Closed off the kitchen doors, and filled the kitchen with steam. Foil on the counter top, alligator clips to bond everything together and an isolation transformer for the soldering iron. I left the protective foam on the chip pins till it was all soldered, then carefully trimmed it away, bit by bit with an Exacto knife after I was done soldering. Degreased it with some borrowed 'tri' and thats the story of our 'hottest' detector. The PD was a small area Hammatasu, at the time, I thought it was to small to use for anything serious, but lately, Im becomming wise to the fact that a small area PD and GOOD lenses have offer superior sensitivity and better 'noise rejection' from ac power light sorces. Even without any lens, and despite the small active area, it easily hears our qrp laser at 1 km. --------------------------------------------------------------------------- group- I also built up a few phototransistor based 741 rx's, all Rat Shack parts. We discovered that they will (just barely) hear the qrp laser at 1 km, so technically they meet the 1 km rule for vhf conests. My idea was that I would give everyone in our contest group a rx, and then they could be motivated to buy their own laser tx's and we would have some extra short range q's for the contest log (at light freqs, u can work ur own ops under the multi multi conects rules). Well, none of the guys ever got into the laser business, so I have them all laying around somewhere. There is no reason why they couldnt be used for short/intermediate range laser qso's. A phototransistor has a severe limitation, that many arent aware of...it has a very very very small active area, in the order of .004 inches by .004 inches. So, getting the light from a lens to totally illuminate it requires extra work and makes them less attractive for us. I would guess that a 1 or 2 inch high quality glass lens with a long focal length would do a good job with the light focusing on the active area tho. But, the long focal length and small active area would make aiming the rx an issue due to the increased directivity... But, it would probably offer UNPRECIDENTED QRM IMMUNITY from local ac powered sodium lights.... Maybe the laser rx and tx could be integrated into a single unit (aim the rx for course alignment and then tweek the tx for 'fine' nadjustments).... At some point, I'd like to quantify the phototransistors actual usable sensitivity...is it possible that they actually rival a PM tube or PD for sensitivity?? Steve, any thoughts on his... --------------------------------------------------------------------------- Per- The info I received from Dave is an intro to laser comm, written by steve. It is awesome and covers beginner to semi-advanced laser comm hardware (rx, tx, aiming techniques and ALOT of background material). Im thinking that u need this material... Can u receive GIf's via email or ftp? I can have my wife scan the material and place it on her web page, in order to make it accessable via internet.... There might even be an easier way...I would think steve would have a text file that could be emailed...but, this would leave 3 pages of drawings, which makes it a little tougher.... Drop me a line about this.... Please tell me about your visual line of sight to Mt Washington on the NH/ME line Per....I can give u an exact heading if needed, its closer to you than equinox is, and my guess is that it would be easily identified if it is visable from there. Equinox = 6+ hours drive time from here.... Montreal = 7+ hours drive time from here.... Mt Washington = 2.5 hours drive time from here.... So, although Mt Washington is less distant, it might be more practical for us to 'test' with..... Let me know.... ---------------------------------------------------------------------- OK, now for the deep though part..... Hey guys, we have a problem (other than my 'verbal frothing at the mouth'). Problem is AIMING... We have resources available and our current state of the art in this department is good, but not great.... I've been thinking about aiming for years and have been looking for comm'l hardware for some time now. OK, so here's what Im thinking..... WE HAVE, in our own human bodies, the most advanced and sensitive optical sensor ever known-our eyes... Nothing else even comes close, Barb, an astronomy major told me that the human eye, when dark adapted, can detect a SINGLE photon! I would guess that our eyes are 1000 times, (probably more) sensitive than the best PM tube ever made. They have awesome dynamic range too. WE HAVE, in our own human bodies, the most advanced computer ever known-our brains. Nothing comes close to them, they process visual imputs from the optical nerve and sort out the data (interfering signals are easily sorted out). On top of all of this, they let us perform other usefull functions too (breathe, think, among other things). So, if we look at 'aiming' as a fundamental problem, how do we put our brains and our own eyes to work as 'tools' to solve the problem, esp'lly regarding initial beam aquisition (course adjustments)? Im thinking that we are NOT UTILIZING 2 of our best resources in an effective manner. In theory, we have sensitivy and data processing ability to spare, and we arent using it well. If we could rapidly move the laser in the X axis, as we slowly scan the Y axis (or visa versa), I would guess that initial signal aquisition would be MUCH quicker and easier.... If we assume that our eyes are 1000 times more sensitive than the best rx, then we should be able to use them to detect a beam which has a .01 percent duty cyle-so, we could could scan the beam atleast 1000 beamwidths wide and it would still be detectable if the eye was used... Well, 1000 beamwidths for a really tight 1 mrad laser equals 1 radian, which is 45 degrees!!!! If the 1000 beamwidth is applied equally to the x axis and y axis, then we could do simultaneous 33 beamwidth X axis AND 33 beamwidth Y axis sweeps. This ammounts to 33 milliradians in BOTH X and Y axis and would make initial beam aquisition a piece of cake!!! Imagine, if u only had to aim a 33 mrad laser!!! U might be able to do that with a rifle mounted setup, with a good resting surface... Or, if we apply this scanning to the x axis only, then why should we have to have a variable x axis at all?? Our 'crude aiming' could be done with a boresight and then 'lock it down'...then we would only have to sweep the Y axis!!!! Having to deal with the design of a stable aiming mechanism in 2 axis is a very major undertaking and makes the construction of the aiming mechanism MUCH more complex... Im very seriously thinking that we need to be able to radidly sweep the beam in a varying arc in atleast one axis.... and, if we can sweep the beam at an AUDIO rate, perhaps we dont even have to chop it or otherwise modulate the beam at all!!!! Even better than that, drop the effective bandwidth of the rx down to a couple of HZ and sweep the beam real slow, when the detector sees a 'spike', have it fire a one shot multivibrator...u dont even have to actually listen to the output of the rx with ur ear, and we get all the advantages of a narrow band rx system!!!! 60 HZ and 120 HZ interference from surrounding sodium lamps would be even less of a problem if the rx uses this principle (provided the sensor isnt overloaded), and you would still use electronic filtering methods... So, Steve, I owe this line of thinking to you..You gave me the missing piece to the puzzle in your write up... You told me that even at 45 miles miles, a HENE looks very bright to the eyes!! I was envisioning it as being dim and marginally visable at these ranges. Anyone have any ideas how to sweep the beam in one axis and still have it be aimable in the other axis???? I have thought about that only since I've been writing this message and a couple ideas come to mind... Mount the whole platform on springs or in liquid, then put a counterweight on a motor shaft (off center) and let the vibration move the beam... Or, mount a small mirror on a motor shaft and rotate it with the mirror being in the path of the beam... Possibly, u wouldnt even need a mirror, a small chunk of regular old window glass would probably work FB (and might even be better as it isnt as optically perfect and would provide a little scattering in the other axis as well). Perhaps an electromagnet (vibrator) could be applied to a mirror (placed in the laser path)?? MAYBE this concept could be used to make my .07 mrad lasers 'usable'...if I could sweep the narrow beam up and down automatically, then I could put all my efforts into designing a really precise and tight left/right aiming mechanism??? ------------------------------------------------------------------------ Well, I must say, I've really outdone myself here. Sorry guys, I've been rambling bigtme. Sorry... Signing off, Art..... From sjnoll@ix.netcom.com Fri Mar 15 06:37:14 1996 Date: Fri, 15 Mar 1996 06:30:44 -0800 Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit From: sjnoll@ix.netcom.com Subject: New Photodiode Amplifier Book To: lmcpegr@langate.lmc.ericsson.se, aballen@COLBY.EDU, daveaa1a@pcix.com, jmoss@berlioz.nsc.com, kent.e.britain@tek.com, nc1k@pcix.com X-Mailer: SPRY Mail Version: 04.10.06.22 Content-Length: 1016 X-Lines: 27 Status: RO A new book just came out about photodiode amplifiers. I got a copy for work - it's pretty good, so I ordered one for home too. Be warned though - as usual there's nothing about DC coupling, canceling ambient light, etc. It's transimpedance amp-oriented. It covers noise reduction, bandwidth, nuances of power supply decoupling, and a lot of other stuff. TITLE: "Photodiode Amplifiers - op amp solutions" AUTHOR: Jerald Graeme PUBLISHER: Gain Technology/McGraw-Hill PAGES: 252, hardcover, 105 illustrations PRICE: $49 If you have Barnes & Noble bookstores where you are they give a 20% discount on hardcovers. This is one they'll have to order. Now if you could convince your library to buy a copy, then you wouldn't have to pop for another expensive book! At least check out the Gain Technology web site - it has some schematics, illustrations, graphs, etc., on it along with the detailed table of contents. Kinda neat. 73, Steve J. Noll | Ventura CA | WA6EJO | IEEE | AVS | sjnoll@ix.netcom.com From sjnoll@ix.netcom.com Fri Mar 15 06:41:47 1996 Date: Fri, 15 Mar 1996 06:40:34 -0800 Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit From: sjnoll@ix.netcom.com Subject: Gain Tech Web Page Address... To: lmcpegr@langate.lmc.ericsson.se, aballen@COLBY.EDU, daveaa1a@pcix.com, jmoss@berlioz.nsc.com, kent.e.britain@tek.com, nc1k@pcix.com X-Mailer: SPRY Mail Version: 04.10.06.22 Content-Length: 430 X-Lines: 20 Status: RO What an idiot I am. Here's the URL for the previouslt mentioned web page for Gain Technology: http://www.gaintech.com/gain I have noticed that this page is not 100% reliable. You may have to try more than once. Other sites of possible interest: http://www.optics.org http://www.lfw.com/ The latter is for Laser Focus World magazine. 73, Steve J. Noll | Ventura CA | WA6EJO | IEEE | AVS | sjnoll@ix.netcom.com From aballen@COLBY.EDU Fri Mar 15 09:14:46 1996 X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Fri, 15 Mar 1996 17:12:16 +0000 To: daveaa1a@pcix.com, nc1k@pcix.com, sjnoll@ix.netcom.com, jmoss@berlioz.nsc.com, lmcpegr@langate.lmc.ericsson.se, kent.e.britain@tek.com, aballen@host-04.COLBY.EDU From: "Art Allen, KY1K" Subject: latest stuff Content-Length: 4098 X-Lines: 89 Status: RO Hey Guys, Im more encougarged every day. The list of 'maybe interested' parties grows every day, at this rate we are gonna need a reflector or a usenet group soon.... OK, heres my latest.... ----------------------------------------------------------------------- Per- I'd be happy to send u one of my simple phototransistor receivers. They are on 3 inch by 3 inch perf board and that makes it easy to locate the center (where u need to focus the light), so they are easy to work with and to mount. Power is by 12 v battery and u will need an audio amp. They are nothing more than a Radio Shack IR phototransistor and a 741 op amp. The 741 will drive a small earpiece well, but not a speaker. Send me the mailing address, I can ship anytime. Glad u can accept binary files..that could be a valuable assett, esp'ly where your time is limited and the premium paid for shipping to Canada. ------------------------------------------------------------------------- Jim- Your message to me had aj6t and Kevin Hague listed as 'cc'. Do they want to receive copies of everything, or are u just sending a copy of that particular message to them?? --------------------------------------------------------------------------- group- The verbage yesterday regarding the rapid sweeping of beam was intended as a theoretical analysis of the problem and was intended to plant a bug in everyones ear... making the most of our eyes and our brains in terms of available resources, relative to the problem (initial beam aquisition). Send me comments, or to the group, if the idea is all wet, tell me that too, esp'ly if u tried it before hi hi.... actaul 'practical' implementation of the hardware was not the intention. Yesterday, i did my first usenet-have always had it available, but could never afford it due to telephone access charges... But, now have a local access #, so I got software (free agent) and checked it out. It's a little overwhelming at this point, but it looks good...never unzipped the software till 8 last night, so I am really NEW. Anyway, I ran across the sci.optics newsgroup. Much of it is pretty advanced and very much 'lab oriented and out of our reach', but there is some good info in there. Steve mentioned it might be worth checking out.. If u have a newsreader and usenet access, it might be worth looking at once in awhile. I did find an internet site for listing scientific equipment for sale. Havent checked it out, but one never knows.... I've heard from ve2dub, thanks to Per. Not sure if they want to be included in the group or not...but Mike did say there is some interest in lasers up north and pointed out some other line of sight paths that might be world record distance. Waiting to hear from him on both topics. ----------------------------------------------------------------------- Steve- Thanks for the info on the laser twt's, interesting. Probably not something I need further info on, but the introduction u sent me on it was much appreciated. The document was the Amateur Lightwave Communication, relayed to me by snail mail thanks to aa1a. Hey Steve, can u send the other things u have written via email?? Your writing style is GREAT and u are writing on just the kind of stuff we need.. Im sure we would all welcome the info. Im going to be sending a package to Per, can I send him a copy of 'Amateur Lightwave Communication'?? Dont know about copyright permission... Let me know please. Or, if u have it in text format, maybe u can send it to him directly as I only have it in hard copy form. Regarding the impending rain storm on the propagation vs wavelength topic, I got the rain coat on. Let 'er rip! Make my day.... It looks like a few of us have gotten to the point where they are needing an intro to it. Steve, I wish I could afford that book...ouch, 50 bucks aint cheep. But, would like to have the ISBN, it isnt listed on our Books in Print cd rom. Is it a REALLY NEW publication? If u got a minute, Id like to have the isbn. -------------------------------------------------------------------------- over and out...bye..Art... From aballen@COLBY.EDU Sat Mar 16 08:59:54 1996 X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Sat, 16 Mar 1996 16:57:53 +0000 To: daveaa1a@pcix.com, nc1k@pcix.com, sjnoll@ix.netcom.com, jmoss@berlioz.nsc.com, lmcpegr@langate.lmc.ericsson.se, kent.e.britain@tek.com, KevinHague@aol.com, aj6t@slip.net, aballen@host-04.COLBY.EDU From: "Art Allen, KY1K" Subject: other info Cc: mp_ross@alcor.concordia.ca Content-Length: 7019 X-Lines: 152 Status: RO Hi everyone.... Hey, I've been digging thru the parts here, most of the boxes havent been opened in 3 years! I found my PM tubs, they are Hammattsu R 1617's, I have 3. I also have 3 of the 12 vdc pm tube ps units. In order to make the PM tubes work, I need SOCKETS. The tubes need a 12 pin socket, the pins are standard wire diameter, the same as any other 7 or 9 pin mini vacuum tube. Hammattsu part number is E678-12D. I suspect the Hammatsu sockets are expensive because they are ceramic, in order to insure lowest leakage current, and therefore lowest noise, maybe Im wrong on this. If anyone can help me with sockets for a reasonable price, I would be grateful! Also, a general question... Hammattsu strongly suggests a conductive coating be placed on the outside of the tube, it is flat black in color and is conductive, the idea being to prevent/minimize some sort of long term degradation. I forget what its called, but years ago I called the company and asked them about it. It's a little more complicated than just painting the tube and they wanted over 100 dollars per tube to do the process. I'm wondering...since we dont run the rx for more than a couple hours per attempt... just how necessary is this coating for tubes that arent used heavily??? I did have some custom delrin sleeves made to faciliate the mounting of the pm tubes, and have wondered if the tubes can be wrapped in silver or gold foil to achieve the same result... Probably not a good idea as the surface is shiney and could hurt perforamance, esp'ly stray light pickup. Im wondering if black conductive foam could be wrapped around the tube to achieve the same result as the megaucks factory treatment... Any input appreciated...... ---------------------------------------------------------------------- Per- I found and tested one of the phototransistor rx assemblies. The one Im sending is all mounted in a plastic 35 mm film canister with the transistor on one end and the audio out is the rca plug on the opposite end, just hook up a 9 v battery to the battery clip, and off it goes.... I wanted to include a small 1 inch dia glass lens with it, but I could not find them. I suggest, that due to the small active area of the phototransistor, that u do not use any lens larger than 1.5 or 2 inch max. Anything bigger than that will just make it to hard to aim. I had one running with a 1 inch lens, and it actually did quite well, fairly easy to point it while mounted on a camera tripod. I found that it is helpfull to add a little bias to these particular transistor to increase the sensitivity. I think this could be done if the base lead of the device was available, but it isnt... I discovered that a small red led, powered by a dc source. Position the led 3/4 inches away from the transistor and such that it doesnt block the incomming light from the lens. Experiment with the position, it isnt terribly critical, but my guess is that a 10 or more db improvement can be had.... I will mail it Monday, look in your mail. Most of us use small electric motors or muffin fans with the blade removed to 'chop' the laser beam in order to provide an 'audio tone' for the rx. You might want to start looking for motors to make chopper assy's. I have used 12v muffin mini fans with 36 slots cut, works good, but its a little big. I also use a remote control car motor with only 8 slots cut (slot car motors are very small, light and turn at very high speed and are cheep). My neighbor who races rc cars keeps me supplied, a motor that has 15 races on it is 'worn out' as far as he is concerned...but they work great under no load!!! Per, Dave mentioned being able to hear moon noise with his detector and a 4 inch lens.. I've never tried it before.. I do alot of my optical testing is a dark room in the house, using an uncollimated LED tx. I pulse the LED at audio frequencies, using an ne555 timer chip. A cmos or ttl logic gate set up as a free running oscillator can provide the same function. I know this is not a 'standard' transmitter in terms of output power...but its useull as a relative standard.... Suggest u look into something along these lines... Just some ideas for u. please feel free to drop me a line or send to the group. ------------------------------------------------------------------------- dave- Hey, good to talk to u on the phone last night...I was thinking u were a colorfull character, and the phone call last nite left me with no doubts... I talked to Barb last night and she has given me the green light to go back into laser comm development. So, I'm officially back in the business. --------------------------------------------------------------------------- Group- Hey, I'm going to work on aiming and nothing but aiming. I'm establising a goal of being able to establish initial aquisition in 5 mins or less, IF the target location is known and identifiable... I'm going to do it for 20 dollars or less (not including tripod) costs. No expensive comm'l aiming components allowed hi hi. I'm hopeing that a tripod wont be necessary at all for tx aiming, or atleast that a tripod used for this purpose will be small, lightweight and inexpensive and STRICTLY HOMEBREWABLE. And, the above goals will be met with HENE tx divergence's, those using solid state tx should get faster aquisition. Laser vucc in one hour flat anyone? Seriously, if we can get past this aiming thing, we can do some serious laser work and have some serious fun.... Twisting micromenter knobs and taking a half hour or more to get aquisition cant be much fun. Theres gotta be a better way hi hi. Further, if we can do this with lightweight portable equipment, then we can take advantage of 'hike in only locations' and if the aquisition is quick, then we can do it in the winter too! Whole new worlds would open up... Ideas ????? -------------------------------------------------------------------------- steve- If possible, let me know about the copyright on the amatuer lightwave comm paper, Im making a shipment to Per and would like to send it at the same time, if possible. Also, please advise whether u can send him an email message of the text, this is a whole lot cheaper than paying to send paper by International Snail Mail. Appreciate it if u can get back to me asap on this..... Also, if u comment on the wavelength vs communication length issue, it would be good to have some input regarding IR sources as QRM.... Does the IR QRM largely negate the additional theoretical tx range increases due to improved propagation? Do items such as indistrial smokestacks, home heating systems and things like that emit IR QRM, even though they dont emit visable light ?? Should we really be moving towards IR @ 970nm to make the best range, or do we just end up loosing the advantage because there is more IR QRM on RX? ----------------------------------------------------------------------- Hey, thats about all for me today, we're having a massive snowstorm today, OH JOY... Art... From daveaa1a@pcix.com Sat Mar 16 09:20:48 1996 Date: Sat, 16 Mar 1996 11:08:29 -0500 Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit From: daveaa1a@pcix.com Subject: 1A Update To: sjnoll@ix.netcom.com, lmcpegr@langate.lmc.ericsson.se, aballen@COLBY.EDU, jmoss@berlioz.nsc.com, kent.e.britain@tek.com, nc1k@pcix.com X-Mailer: SPRY Mail Version: 04.00.06.17 Content-Length: 1374 X-Lines: 28 Status: RO Howdy Folks: Previous week spent stripping 60khz. and 100khz Loran 'C' PRF for local timing project. Shining up last years model 10ghz transverter to take to the hills. Laser Thoughts: Celestron with Crosshairs takes the prize for the best Rx improvement to this 4" rig. Looking for CCD Camera to try at output of the Celestron. Also making pivot assy. to flop PIN diode into eyepiece once sighted. Put reflective vehicle number plate out on the old EME tower for adjusting registration with Laser Diode mounted to 4X rifle scope and X-Y heavy aluminum table mounted on end. Thanks for the URL's: www.gaintech.com/gain is nice but that optics.org gets deeper right away with /advsearch.html showing pieces of the Op-Amp Book. RADIOKIT of Pelham, N.H. has sent out a flyer with much HP and TEK test equipment for sale. Their Phone is 603-635-2235 or FAX 603-635-2943 TWT's etc. also.. Am canabalizing ccd camera and video amp to use with no scanning, just light focused on the element and amped up to and limited to data level. Has anyone tried a nightscope on the output of a Telescope?? Been using EG&G PIN #VTP1188s as per Steve. New Newark Catalog #114 shows Photodiodes with areas from .032 sq. in. to .607 sq. in. VTS series with prices from 3 to 57 bux.. Looking to go local outside now that we are at least un-frozen for some 10 mile +/-... 73's de Dave From sjnoll@ix.netcom.com Sat Mar 16 23:31:03 1996 Date: Sat, 16 Mar 1996 23:25:44 -0800 Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit From: sjnoll@ix.netcom.com Subject: PMT Sockets and Coatings. Laser EME. To: aballen@COLBY.EDU, daveaa1a@pcix.com, jmoss@berlioz.nsc.com, kent.e.britain@tek.com, nc1k@pcix.com, lmcpegr@langate.lmc.ericsson.se X-Mailer: SPRY Mail Version: 04.10.06.22 Content-Length: 3435 X-Lines: 67 Status: RO Yo opto-dudes: So much info - so little time! This is fun. Art: PMT Sockets - just checked my stock. Have a bunch for 931As, but not for small pin size Art needs. Bummer. Lemme tell you what I did on my last PMT receivers... These use big 2" end-view PMTs - some old experimental red-enhanced tubes someone gave me years ago. They're something like 14 large pins and a standard phenolic-type base. I think I actually found sockets but I didn't use them. I soldered the resistor chain directly to the pins - thus lowering the leakage. I don't think that you could get away with that on a tube that has those small pins that go directly thru the glass base. How about taking apart some female connectors - like DB's - and use just those female sockets to fit over the tube pins. Solder the resistor chain to those sockets first. I mounted my tubes socketed this way to a pc board ring (collar) via some silicone sealant bumps. That gave me a way to mount the tube and good shock (mechanical) protection. PMT Conductive Coating - I have found references to this in RCA, Hamamatsu, and Philips literature here. Hamamatsu calls it a "HA-Coating." From what I see it can have a slight noise advantage for some tubes, but doesn't seem to be a standard feature. The coating is always connected to the cathode potential. This can be via a large resistor to avoid shock potential if you operate in anode-ground mode. A RCA graph of the effect of an external-shield potential on a 1P21 shows the Equivalent Noise Input reduced from 2 picolumens at 0 volts to 0.5 picolumen at -1KV. Reduction in ENI is going to translate directly to longer range. I suspect that this coating does not have to be extremely conductive. First thing that comes to mind is something they used to call "Aquadag" paint. I believe it was for repairing the conductive external coating on TV picture tubes and that it was black. GC Chemicals has an "EMI-RFI extremely conductive graphite coating", a "Silver Print Conductive Paint", and "Nickel Print Conductive Paint." Try a local parts store. Photodiode Amplifiers Book - It is a really new book, just out. I've got an ad that Gain Technology ran for it - it has everything except the ISBN! It isn't on their web page either. My work copy is at work, as well as the P.O. - which I put the ISBN on. I can get it Monday (If I remember to write myself a note!) Kent: Wow - I never thought you'd be able to feel the heat from those little CD player diode lasers! That's amazing. Probably can get a view of the beam with a liquid crystal sheet? Laser EME - I saw a film on NASA bouncing a signal off of the lunar retro-reflectors long ago. I think that there are several reflectors scattered about, including some Soviet ones. If I recall correctly, they were using a green (doubled-YAG) pulsed laser through a large telescope. What impressed me was with all the money and equipment they had - they didn't get a return on every shot. They were really counting photons. It was flaky. I realized at that moment I should stop trying to see a red dot up there from my 2mW HeNe! I think the reflectors are high quality cube-corner prisms in an array a couple feet square - so what goes up comes straight back. Hey, let's do cloudbounce! Over The Horizon Laser DX? 73, Steve J. Noll | Ventura CA | WA6EJO | IEEE | AVS | sjnoll@ix.netcom.com From sjnoll@ix.netcom.com Sun Mar 17 10:06:41 1996 Date: Sun, 17 Mar 1996 10:01:16 -0800 Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit From: sjnoll@ix.netcom.com Subject: Another old West Coast VHFer column - Laser Safety To: aballen@COLBY.EDU, daveaa1a@pcix.com, jmoss@berlioz.nsc.com, kent.e.britain@tek.com, nc1k@pcix.com, lmcpegr@langate.lmc.ericsson.se X-Mailer: SPRY Mail Version: 04.10.06.22 Content-Length: 3906 X-Lines: 121 Status: RO Here's another old (10/91) West Coast VHFer column for your edification and amusement: LIGHT NOTES... Should Amateur Lightwave Communicators Be Concerned About Laser Safety? For some time I have been concerned about the laser safety question. I've heard some Hams suggest using powers in the Watt range for cloudbounce, for example. And what about the 30 mW power level of the lasers used in the recent Helium-Cadmium 154 mile record? The American National Standards Institute (ANSI) addresses laser safety in their ANSI Z136.1-1986 standard: "American National Standard for the Safe Use of Lasers." I'll attempt to boil down its 90 pages of text, tables, and charts into something comprehensible. Lasers are classified according to the hazards they present: CLASS 1 generally covers microwatt level ultraviolet lasers, visible lasers under 0.4uW, near infrared lasers (0.7um - 1.4um) between 0.4uW and 200 uW, depending on wavelength, far infrared lasers under 0.8mW. These are considered inherently non- hazardous. CLASS 2 lasers have the same limits as Class 1, except in the visible (0.4um - 0.7um) range where they measure between 0.4uW and 1mW. CLASS 3 generally covers lasers up to 0.5W. Direct exposure is considered hazardous. A diffuse reflection is not considered hazardous. CLASS 4 covers lasers over 0.5W CW and are hazardous to both eyes and skin. Usually the Class rating is marked on a commercial laser. Most Ham Radio work is likely done with Class 3 visible or near infrared lasers. Class 1 is probably too low in power to be of any use. If use of a Class 4 laser (>0.5W) is contemplated, think twice! Eye damage is likely for anyone walking (or aircraft flying) into the beam path. This Class rating business doesn't really tell us much about the hazard. What about miles in front of the laser where the beam is less intense? Is the hazard lower there? Yes, and ANSI shows how to calculate the exact Maximum Permissible Exposure (MPE) as they call it. MPE factors exist for different wavelengths and exposure times. For > 0.25 second eye exposures: Helium-Cadmium 441.6 nm = 1uW/cm2 Argon 448 nm & 514.5 nm = 1uW/cm2 Helium-Neon 632.8 nm = 17uW/cm2 Nd:YAG 1064.0 nm = 1.6mW/cm2 CO2 10600.0 nm = 0.1W/cm2 Now, to get how far away from the laser you have to be to avoid eye damage: (Z136.1-1986 B4.2.1) __________ 1 / |1.27*Power \ Dist = --- ( /\|---------- - Dia) Diverg \ \ MPE / Dist = distance in centimeters. Diverg = beam divergence in radians. Power = laser power in Watts. Dia = beam diameter at laser in cm. Let's plug in some real numbers... Helium Neon (632.8nm) 1mW, 1 mRadian, 1mm Dia, Dist = 280' 10mW " " Dist = 893' Helium Cadmium or Argon 1mW, 1 mRadian, 1mm Dia, Dist = 1166' 30mW " " Dist = 6400' Argon (488nm & 514.5nm) 1W, 1 mRadian, 1mm Dia, Dist = 7 mi. 10W " " Dist = 22 mi. Within these distances you must guarantee that no one can cross the beam path. That means aircraft flying though the path too. Further, the FAA regulates navigable airspace and might want to have a say in such matters (Z136.1-1986 7.6.1). Be careful!!! 73, Steve J. Noll, WA6EJO 1288 Winford Avenue Ventura, CA 93004-2504 .................................................................. Note that the ANSI distance formula doesn't take into account the Atmospheric Attenuation Coefficient: -BZ T = e or Transmittance = 2.72 raised to the negative product of the Scattering Coefficient times the distance. This really takes a toll on visible, but less so on IR. A topic I want to get into later. 73, Steve J. Noll | Ventura CA | WA6EJO | IEEE | AVS | sjnoll@ix.netcom.com From aballen@COLBY.EDU Sun Mar 17 12:59:27 1996 X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Sun, 17 Mar 1996 20:57:36 +0000 To: daveaa1a@pcix.com, nc1k@pcix.com, sjnoll@ix.netcom.com, jmoss@berlioz.nsc.com, lmcpegr@langate.lmc.ericsson.se, kent.e.britain@tek.com, KevinHague@aol.com, aj6t@slip.net, aballen@host-04.COLBY.EDU From: "Art Allen, KY1K" Subject: Re: PMT Sockets and Coatings. Laser EME. Content-Length: 5555 X-Lines: 136 Status: RO At 11:25 PM 3/16/96 -0800, you wrote: >Yo opto-dudes: > >So much info - so little time! This is fun. > >Art: > >PMT Sockets - just checked my stock. Have a bunch for 931As, but not >for small pin size Art needs. Thought about descrete individual connectors, presumably, the Hamamatsu ones are so expensive because they are gold plated?? Anyway, I found suitable gold plated mil spec indvidual pins, but they were gonna cost 1 dollar each, and decided against them at the time. Was hoping to find the right socket assembly, so I wouldnt have to kludge anything. hi hi. I'll keep looking. I was wondering about gold or silver foil, and just wrapping it around the tube. Didnt know whether the shiney surface would reflect stray light or not..and light that is reflected when it shouldnt be has to be devastating to the performance, esp'lly if its 60/120 hz QRM.... Was thnking of gold/silver because of the low oxidation rates...any oxidation on the foil surface would probably create electrical noise. I had looked at the spray coatings, but the are all shiney, didnt know about the stray light situation. Was really hoping someone had tried black conductive antistatic foam..its cheap, available and since the currents are very small, it should shunt away unwanted electrons on the glass surface without a hitch. Hadnt tried it, wondered if anyone else had, or whether anyone had heard anything about it. >Photodiode Amplifiers Book - It is a really new book, just out. OK, its just a matter of time till its listed steve, sometimes it takes awile to go from the market to the actual BOOKS In Print hard copy, I'll keep watching. Dont worry about the ISBN, it will show up in the listings eventually. >Kent: > >Wow - I never thought you'd be able to feel the heat from those little >CD player diode lasers! That's amazing. Probably can get a view of the >beam with a liquid crystal sheet? You can feel the heat from a 1 mw HE NE beam. Stand around, outside in the cold without gloves on. After you hand becomes 'cold adapted', the beam actually feels quite warm!!! Take it from someone who knows... Incidently, my .07 mrad lasers do not allow me to feel the heat from the beam. Their outputs are .75 inch diameter tho. Probably because the beam is spread out so much. > >Steve J. Noll | Ventura CA | WA6EJO | IEEE | AVS | sjnoll@ix.netcom.com ----------------------------------------------------------------------- Per- Found the 1 inch glass lens' I knew I had, its amazing what u find when u start scraping the bottom of those junk boxes... I suggest that u use it, initially, if u need a more sensitive rx, u will probably build a different typee of rx anyway. The phototransistor/1 inch lens combo should be real rugged and good for quite a few km. As I said earlier, the transistor rx, even without any lens, can hear my qrp laser at 1 mile... So, the 1 inch lens should provide quite a good short to medium distance rx. GO FOR IT. It will be in the mail on Monday. ------------------------------------------------------------------------ Steve- The write up I was referring to is the 26 page Amat Lightwave Comm, Practical and Affordable. If u have it in ascii form, Im wondering if u can ship it to Per via email?? If u can do that, I can photocopy the 3 pages with graphics on them and ship them via snail mail with his rx. Let me know whether u can email the text to him, it would be alot cheeper than paying the postal rates to ship the paper. -------------------------------------------------------------------------- Dave- In my junkbox searching Friday and yesterday, I found my old technical library. In the 1991 Hamamatsu Catalog, there are application notes and schematics for such subjects as 'high speed light sensor', 'high speed sensor using video amp', and 'light sensor using high speed operational amp'. FYI, all 3 schematics specify a PIN diode, I think u probably already knew that.... But, it shows schematics and lists chip types too... Let me know if u want the hard copy...maybe u have already seen similar info.. ------------------------------------------------------------------------ group- Hey, I started doing my aiming research and Im using my QRP 12v integrated HENE and PS combo. A small package, handy for dubbin around. Anyway, wanted to share a tip with the group.... Even a 1 mw laser is bright and possibly dangerous. Certainly, if u are testing on an indoor range, there is NO NEED to dub around with the laser at full intensity..even the reflection is to bright. Well, years ago, I tried various attenuation schemes and found limited success, everything I could do to attenuate the beam would also scatter it to a large degree. Finally, I discoveed that regular old brown plastic 'shipping tape', non reinforced type, did a wonderful job. It probably knocks down the intensity of the beam by 30 or more db, and its scattering is minimal...it's cheep too. Even in daylight, the beam is visable on the wall at 20 feet and in a semidarkened room, it is actually alot brighter than it has to be.. Just wanted to pass it along. I found the tech specs on the PD's we bought years ago... The one we are currenly using in our PD rx has a 1.1 by 1.1 mm active area. Thats really small, and probably not usable on anything other than glass optics. The 'spares' which are currently unused and stored are 5.8 by 5.8 mm, alot more practical for fresnel light gathering. ------------------------------------------------------------------------- hey, have a great day...Art... From sjnoll@ix.netcom.com Sun Mar 17 21:38:45 1996 Date: Sun, 17 Mar 1996 21:33:32 -0800 Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit From: sjnoll@ix.netcom.com Subject: PMT Coatings, QRM, Fresnel Lenses, Photodiode Quality Measurement. To: aballen@COLBY.EDU, daveaa1a@pcix.com, jmoss@berlioz.nsc.com, kent.e.britain@tek.com, nc1k@pcix.com, lmcpegr@langate.lmc.ericsson.se X-Mailer: SPRY Mail Version: 04.10.06.22 Content-Length: 2574 X-Lines: 58 Status: RO Howdy Guys: Art - I'd like to send you a couple copies of the handouts for the '94 Microwave Update talk. There are improved schematics & drawings in it as well as parts lists and circuit board layouts -which aren't in the paper. Is your Amherst Rd address still good? I see in the MCM catalog that GC has "Television Tube Koat" conductive graphite-pigmented spray lacquer, $7.39/12 oz. This should be black - and is the "aquadag" type stuff I mentioned. I suspect IC foam would work - as long as no real current flows thru it - which it shouldn't. I've used it to spoil the Q of a 10 GHz preamp box - glued it under the lid to stop resonant oscillation. I would think that the IC foam might serve to stop the PMT field emission, but I'm not so sure how effective it would be at blocking 60/120Hz because of its relatively high resistance. I have seen this stuff available in two resistances, by the way. I can't believe gold PMT socket pins would make a measurable difference. IR QRM - I think that the bulk of IR radiated from warm objects is of significantly longer wavelength than the 700 to 900 nm range. I haven't done any research on this, but I don't think this is a problem for us. On QRM in general - I never had that much problem with it. One reason is that I have 12" long 4" diameter light shields on my current receivers - in front of the lenses - and these are some of the shortest shields I've used. Also, instead of painting the insides of such shields black, line them with black flocking adhesive-backed paper. Edmund sells this stuff. I use it at work for lining critical optometric microscope tubes to keep the internal reflections down. It's much much blacker than flat black paint - expecially at glancing angles where the paint still reflects a lot of light. Besides that, It's probably better at IR than black paint. Will be getting to the range vs wavelength issue. ....... Everyone: FRESNEL LENSES - Anyone know the efficiency of a typical fresnel lens - compared to a standard glass lens of similar area? PHOTODIODE QUALITY MEASUREMENT - The single most important measurement of quality of a photodiode is its dark current. The dark current can be equated to the photodiode Equivelent Noise Input, or how weak a signal it will detect. This measurement is not hard to do. I can fill you in on how to do this if you don't know already. 73, Steve J. Noll | Ventura CA | WA6EJO | IEEE | AVS | sjnoll@ix.netcom.com Steve J. Noll | Ventura CA | WA6EJO | IEEE | AVS | sjnoll@ix.netcom.com From aballen@COLBY.EDU Mon Mar 18 11:26:55 1996 X-Sender: aballen@colby.edu (Unverified) X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Mon, 18 Mar 1996 19:24:49 +0000 To: daveaa1a@pcix.com, nc1k@pcix.com, sjnoll@ix.netcom.com, jmoss@berlioz.nsc.com, lmcpegr@langate.lmc.ericsson.se, kent.e.britain@tek.com, KevinHague@aol.com, aj6t@slip.net, aballen@host-04.COLBY.EDU From: "Art Allen, KY1K" Subject: motor suppliers? Content-Length: 865 X-Lines: 22 Status: RO Hey Everyone.... I've been dubbing aroud with some different aiming concepts, my first choice is a 'hands off' mechanism....I think the extra expense involved in constructing a no hands system would be offest by the advantage that u could use a 'less than optimum' tripod assembly and stand back from it and direct it by wire or light beams.... I'll see how it goes, will keep everyone posted. Towards this end, I need some REALLY SMALL dc geared motors. Precision is not necessary. And micro power is ok...a microminiture slot car motor would be great, if it had gear reduction. Need speed in the 2 rpm or less range. Must be dc and reversable. I'm looking for something that is lightweight.... Anyone know if motor suppliers? I checked the Granger catalog, they have industrial type BIG motors. anyone know of suppliers of stuff like this ??? Bye...Art... From sjnoll@ix.netcom.com Tue Mar 19 06:52:20 1996 Date: Tue, 19 Mar 1996 06:47:06 -0800 Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit From: sjnoll@ix.netcom.com Subject: "OpticalAmateurCommunicationsSociety" To: aballen@COLBY.EDU, daveaa1a@pcix.com, jmoss@berlioz.nsc.com, kent.e.britain@tek.com, nc1k@pcix.com, lmcpegr@langate.lmc.ericsson.se X-Mailer: SPRY Mail Version: 04.10.06.22 Content-Length: 2382 X-Lines: 77 Status: RO I see four of us are on the mail server now. Two more to go? Found on sci.optics.fiber. Just for your amusement... ======== Path: ix.netcom.com!ix.netcom.com!howland.reston.ans.net!swrinde!newsfeed.inte rnetmci.com!EU.net!sun4nl!knoware.nl!hilversum.knoware.nl!user From: ko@komac.knoware.nl (Ko Stoel) Newsgroups: sci.electronics.design,sci.optics.fiber, Subject: forming OACS ;OpticalAmateurCommunicationsSociety Date: 18 Mar 1996 16:15:02 GMT Organization: Knoware Internet Lines: 48 Message-ID: NNTP-Posting-Host: hilversum.knoware.nl Xref: ix.netcom.com sci.electronics.design:6426 sci.optics.fiber:459 I would like to meet people that are interested in Open air cellulair optical communications. (no fibers) Phase 1 IMO it is an interesting idea to have a central semiplane-omnidirectional IR transmitter/receiver on a high point and around it clients that can start with a simple optical/electronical IR to RF radio/tv converter to insert standard RF signals into their TV's . This simple IR receiver needs to be accurately directed towards the closest central point and have a clear view to it It would need an analog broadband IR laser modulator of sufficient power. Phase 2 The simple client receiver is extended with a IR transmitter of sufficient power to reach the omnidirectional central IR receiver. Possibly in an other IR band. For this purpose a specific HF bands are reserved and can be modulated into the IR . No RF signals are allowed into open air thus not conflicting with any regulations. A specific RF band could be used to modulate 100Mps fast ethernet To have an open citizensband-network Other RF bands could be used to experiment with other new networkrelated protocoles (ATM). Security issues are to be discussed too... Important is to tap into existing consumer electronics installed-base and bootstrap from there into newer applications. If you are interested and think you could contribute in one of the subfields ; please state level of competence ... Also if there's no theorethical limitation and with ample interest it could be interesting to form something like OACS (pron. oaks) I'll wait 2 weeks and then I'll will summerize responses ing. Ko J.J. Stoel ko@komac.nl PE1BFE HOLLAND 73, Steve J. Noll | Ventura CA | WA6EJO | IEEE | AVS | sjnoll@ix.netcom.com From aballen@COLBY.EDU Tue Mar 19 08:20:32 1996 X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Tue, 19 Mar 1996 16:18:06 +0000 To: daveaa1a@pcix.com, nc1k@pcix.com, sjnoll@ix.netcom.com, jmoss@berlioz.nsc.com, lmcpegr@langate.lmc.ericsson.se, kent.e.britain@tek.com, KevinHague@aol.com, aj6t@slip.net, aballen@host-04.COLBY.EDU From: "Art Allen, KY1K" Subject: Re: motor suppliers? Content-Length: 2637 X-Lines: 59 Status: RO At 08:05 PM 3/18/96 -0500, you wrote: >I agree with a hands off method and believe one way of doing some of that is >with servo's, maybe from an old R/C car/plane set. It could be possible to >aim this system by hand and then go to the geared down servo's for more >accurate aiming?????? Any thoughts??? > >-Kevin > > Hey Kevin, Yes, that occurred to me, along with wireline servos too. 400 hz servos are available fairly cheeply and use low power. Some do not need continued power to maintain their position AFTER they have had time to settle. Stepper motors are cheeper even, and 7.5 dergee per step motors are freebee items in junked printers... I have been doing research here, on a prototype basis, in order to determine which 'concept' was feasable to warrant further develpment.... Nothing I've thrown together on the kitchen table 'test range' has been a finished product, but I've investigated quite a few 'hands off' methods. Years ago, I did alot of thrashing around with aiming hardware using 'hands on' techniques. Without going into alot of details, the 'hands on' methods require tight tollerences and interact in the x/y axis..and they are tough to build and use because the torque of your body moving a lever or twisting a screw throws everything off. To counteract this, u need BIG HD tripods and other special 'considerations'. Well, 'hands off', methods as I've just discovered in the last couple of days do not have these problems... I have used 3 different 'concept' mock ups here, and EVERY SINGLE one of the 'hands off' concepts works GREAT. My biggest and most promissing 'concept' involves a syringe and latex sugrical tubing... INCREDIBLY STABLE, extremely cheep and easy to fix in the field! This is so easy, and is so STABLE, it's scarey!!!! My most 'off beat' method involves magnetic coupling and a 'floating platform' on which a mirror is mounted... and a stepper motor. I believe the stepper motor isnt necessary at all, I think that dual electromagnets could do the same job, but haven't checked it out further. I'll give more details later, but I would encourage everyone to look for cheep and dirty ways to aim a beam using 'hands off' methods.... hey, the comet was awesome last nite-visable with the naked eye. Last night we looked for it and didnt see it till about midnite. Try about 20 degrees south of east (magnetic) at about (Im guessing) 35-40 degrees elevation at around midnight. It visable without binoculars, and it looks like a BIG fuzzy star. If u have even low power binoculars, it is VERY nicely viewed, we didnt even drag out Barbs telescope. Bye for now....Art.... From majordomo-owner@berlioz.nsc.com Tue Mar 19 09:00:30 1996 Date: Tue, 19 Mar 96 09:00:29 PST To: jmoss From: majordomo@berlioz.nsc.com Subject: Majordomo results Reply-To: majordomo@berlioz.nsc.com Content-Length: 174 X-Lines: 12 Status: RO -- >>>> who laser Members of list 'laser': kevinhague@aol.com jmoss sjnoll@ix.netcom.com daveaa1a@pcix.com aballen@colby.edu kent.e.britain@tek.com lmcpegr@lmc.ericsson.se From aballen@COLBY.EDU Tue Mar 19 11:20:23 1996 X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Tue, 19 Mar 1996 19:18:08 +0000 To: daveaa1a@pcix.com, nc1k@pcix.com, sjnoll@ix.netcom.com, jmoss@berlioz.nsc.com, lmcpegr@langate.lmc.ericsson.se, kent.e.britain@tek.com, KevinHague@aol.com, aj6t@slip.net, aballen@host-04.COLBY.EDU From: "Art Allen, KY1K" Subject: aiming Content-Length: 3336 X-Lines: 71 Status: RO It appears most of us have 'aiming problems', or atleast that we identify it as a MAJOR problem (have never heard anyone say they didnt have enough TX power or RX sensitivity yet) hi hi! I'd like to talk about the method we use, esp'lly as it relates to world class distance qso's. I found the 1990 copy of the QST account of the world record laser qso by the AZ 7 landers. In that article, it mentions high power filament type lights and big flashtubes, and notes that they arent highly visable despite massive ammounts of power. If, we look at this and ask ourselves WHY, it becomes clear I think... Check out the power density at 100++ miles !!! Sure, they start with 100 or more watts, at the tx, but at 5 to 15 degrees divergence!!!! This could still give a reasonable signal at a good distance, but there is no doubt that the power goes away FAST at those wide angle divergences..... Another BIG problem, and one most of us havent thought about, is the SPECTRAL output of those filament based lights! Theres everything from near violet to way invisable IR in those beams... If we looked for that dx light source with an IR RX, I bet it would be blinding...there has to be a wicked ammount of IR in the spectrum of a filamant light! The wide spectral output creates another problem tho. The atmosphere is full of ducts for light. And, different lambda light is deflected differently once it leaves the tx. So, the separation of the various wavelengths means that the nice white light that starts out doesnt get to us at the far end of the path. Also, the reds (since they are longer lambda), are favored by the atmosphere so blue/violet/green are not nearly as likely to be seen at the end of a long path. When one considers all of this, it doenst take a rocket scientist to understand WHY those flashtubes and HUGH filament spotlights dont make it, atleast in the high dx mileages. ------------------------------------------------------------------------- Well, basically, we need to be able to SEE the far end of the path in order to be able to work it. We do this usually by shineing a spot light or some other energy source at the transmitting station. The transmitting station uses that energy to 'locate' and aim by... If we use 10 ghz, with a reasonable small dish, we can determine the heading of the qso partner to within a couple of degrees. If we use a compass, we can do about the same. North Star...about the same. If we can see a filament lamp or flash tube, we know where the other station is (almost exactly). Maybe we should be using monochromatic laser light for this purpose to start with! The use of flash tubes and filament lamps for this purpose is expensive, requires alot of power (tough for portable operation), makes u night blind and just plain doesnt work for longer distances. Could a sweeping laser beam and the combination of some other azimuth 'course aiming' method provide better results for long distance qso's ???? Maybe, instead of buying a big spotlight or flash tubes, perhaps we should be building a second laser that sweeps 10 degree vertical and 10 degree horizontal...then use that for a target? Maybe set it up on the RX tripod and actually use it for course aiming the rx even??!! Hey, something to think about..... Ideas, opposing viewpoints ?? Bye...Art.... From kent.e.britain@bangate1.tek.com Wed Apr 3 07:56:40 1996 From: kent.e.britain@bangate1.tek.com Date: Wed, 3 Apr 96 5:52:17 CST X-Priority: 3 (Normal) To: Subject: re: passive repeaters Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Length: 423 X-Lines: 11 Status: RO Hello Jim: There have been some experiments illuminating a polished sphere to distribute modulated Laser energy, but it takes a lot of power. A retro reflect returns the energy to the uses. 8 years ago KY7B and I expored the possiblities of Laser EME. We got the specs on the Laser retros left behind by the Apollo astronauts. Those retros were so good, a beam from Arizona was returned to Arizona.!! Kent WA5VJB From kent.e.britain@bangate1.tek.com Wed Apr 3 11:25:55 1996 From: kent.e.britain@bangate1.tek.com Date: Wed, 3 Apr 96 9:20:17 CST X-Priority: 3 (Normal) To: Subject: re: passive repeaters Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Length: 497 X-Lines: 16 Status: RO Hello Jim: We were looking a ham Laser EME. The labs are running very high power, but extremely short bursts, on the order of 1 Nano-Second ride time. Great for accurate ranging, but not many photos in the beam. Yea, I've seen photos of that satellite, a sphere of corner cubes. Our plan was to use Liquid Dye lasers, modest optics, aim at a common point on the dark edge of the moon. Modulate the Laser at say 1000 Hz, then use audio filters and go looking for the 1000 Hz. 73's Kent From larson@w6yx.stanford.edu Sat Apr 6 19:52:02 1996 Date: Sat, 6 Apr 1996 19:51:18 -0800 From: Alan Larson To: jmoss@berlioz.nsc.com Subject: Re: Spectrum watch? Content-Length: 752 X-Lines: 28 Status: RO > New product announcement in March 28, 1996 EDN > Single-chip VHF/UHF transceiver implements spread-spectrum system > Page 42 > "The device operates from 300 to 500 MHz; typical operation is 433.92 MHz." > 1-5mW out, 20-40m indoor range Rx is -60dBm sensitivity for 20dB S/N > Manufactured in OSLO, NORWAY. $31.00 > Jim > WB9AJZ/6 CM87xi Sunnyvale, CA Indeed, I thought 433.92 MHz was amateur in most (if not all) of the world. If they want to sell them to the amateur market, a bit more power might be useful... Alan wa6azp p.s. weren't you talking about laser diode modulation at the microwave meeting a while back? Do you have any write-ups on how this is done? I would be kind of intersted in trying it with video signals. From aballen@COLBY.EDU Mon Apr 15 08:19:30 1996 X-Sender: aballen@colby.edu X-Mailer: Windows Eudora Light Version 1.5.2 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Mon, 15 Apr 1996 15:17:31 +0000 To: jmoss@berlioz.nsc.com (Jim Moss) From: "Art Allen, KY1K" Subject: Re: steppers Content-Length: 2586 X-Lines: 68 Status: RO At 10:10 AM 4/12/96 PDT, you wrote: >Great info avail able on >www.cs.uiowa.edu/~jones/step/index.html > >see also >zebu.uoregon.edu/~mbartels/altaz/altaz.html > >I've got a bunch more too. >Been researching this on internet for the last week and a half. > >These telescope guys have stuf well under 1mR. > >another good site (but slow) >www.newport.com/tutorials/Motorized_Actuators.html > >I bought 2 sets of motors: >a pair of bipolar steppers 1.8 degree. These need an H driver, looking for > a chip to do it. NSC makes one but have to find it. >a pair of unipolar steppers 7.? degree. These are simpler to control. > from old floppy disks. > >Haven;t started bench work yet. I have next week off!!! Hmmm. > If only I didn't have to paint the house, sheet rock, texture, paint the > garage, and then build organizers! > >Jim >WB9AJZ > > Hey Jim, I spent 4 hours on this over stuffed punch box last nite, and got some GREAT info. Thanks for pointing me in the right direction! I was not able to find any actual usable info from the newport.com site tho....mostly advertising hi hi. Hey, the dobsonian telescope was great, his method of drive looks really flakey tho, basically a friction drive from what I can see, and a HUGH plywood circular disk? That can't be very 'linear'. Interesting tho. It looks like the software he wrote is great, the concept of sighting on 1 star, then sighting on a second star and then pushing a button to put ur scope on the desired star is GREAT tho! If we are to proceed into the 100 mile + laser range, or if we are to use IR tx's, then we will have to develop a similar technology. Its possible we can 'aim' at 2 known targets for calibration (lighted radio towers), then swing the beam around so that it points towards the desired target. The heart of this is the capability of calibration and the ability to move the az/el more than a few degrees. Most of the aiming stuff I've dubbed around with only moves 3 or 4 degrees, at most; and it isn't 'calibrated'. It would seem that we would about 180 degrees azimuth and 90 degree elevation capability if we are to use this concept. But, the advantage of not really having to 'see' the qso partner is a great advantage too. For slr work, we will need this 'wide range' az/el capability too.... Im going to continue researching 'narrow' range aiming systems where we can see the target for now. SLR and 'wide range' aiming technology later I think. Bye for now and GL, again, tnx for the pointers on the stepper motor drives. Keep the group informed of your progress! Art.... From jmoss Thu May 23 11:42:21 1996 To: laser Subject: Cheepo Laser "CW" Transceiver Content-Length: 6207 X-Lines: 156 Status: RO Cheepo Laser "CW" Transceiver by WB9AJZ/6 Jim Moss jmoss@berlioz.nsc.com Parts can all be found at Radio Shack. Feel free to substitue better parts or redesign at will. There is no ownership, or responsibility for this design associated with me. Use at your own risk! But have fun! Use care when operating lasers, as they can cause eye damage. More on this another time. Just don't look into the beam for now. Receiver -------- Parts: TL082 opamp, rs# 276-1715 LM386 audio amp photo transistor rs#276-145a 10Mohm Resistor 150Kohm Resistor 3 .01uF capacitors 10k pot 2 10uF caps 50 uF cap 2 battery clips 2 9v batteries 2 9v battery connectors 1 earplug speaker 1 1/8" sub min jack double perf board with copper, break in half Forgive the "TEXTUAL" drawing: I'm sure you can improve on this mediocre design. +9v | \ 1/2 TL082 1/2 TL082 LM386 / 10M \ .01uF 3|\ 1 .01uF 5|\ 7 .01uF 10K pot /-----||------|+\--+----||------|+\---+-||-----\ |\ 50uF |/ ---|-/ | ---|-/ | / 3| \ 5 + ~~| | 2|/ | | 6|/ | \<----|+ \-----||--center |\ |_______| | 150k | / |--|- /1 10uF of v \/\/\/\/ \ | 2| /----||--| jack | Note: TL082 power is pin8 to +9v | | |/8 + | -9v pin4 to -9v -9v -9v \_________| Note: LM386 pin 6 to 0v pin 4 to -9v 10uF cap from 6 (+) to 4 OK thats the Receiver. Should take about an hour to build. To test it, just turn on a light and listen to the buzz. You can adjust sensitivity by changing out the 10M resistor with a smaller one. ie. 1M or 100k or 10k. The pot can adjust volume (somewhat). The 386 is strong enough to drive a small speaker (like computer type). Transmitter ----------- Parts laser pointer (any will do, but look for one you can route a wire pigtail out of without destroying it! Then you can still use it for work! I am trying to standardize here on 670nM, but you can choose. this only becomes important when you start using bandpass filters. I run a 4mW one.. you can use 1-5mW. Fry's here in CA has sales with their cheepest at 29.99+tax. beam looks OK, but a bit broad. LM555 astable osc NPN xsistor (your choice of #) 4.7k resistor 10k resistor 15k resistor 10k pot 8.2k resistor (you can change this) .068uF cap 2 1/8" jacks 2 1/8" plugs (1 for keyer, 1 for laser) 1 9v battery connector 1 9v battery 2 9v battery clips (1 for laser, 1 for battery) 1/2 (the leftover half) PC perf board (about 2"x2") Goal is to build a on/off controllable 800Hz oscillator to key the laser. You can adjust .068 cap and resistors as you like. 10k pot 4.7k \/\/\/--\/\/\/-- .068uF T | ----------------+----||--- | | 15k | | | \-----+9v +/\/\/+ n/c to pin GND | | | | 2 --------------------------- | 8 7 6 5 | | LM555 | | | | 1 2 3 4 | --------------------------- | | | | GND to pin | +-----------------On/Off Key to +9v 6b | \ | / 8.2k /------Keys laser | \ | | | | (optional) | GND +-\/\/\/\-- +9v | / 10k | 1.5k |/ \--/\/\/\/\---| NPN of choice |\ V GND Inside the laser you will find the switch that turns it on and off. Identify the ground and voltage sides with a VOM. Connect ground of laser to ground of cct. Connect hot side of switch to "keys laser". Use your keyer or hand key or switch to key the "ON/OFF KEY". One side goes ot this pin the other to +9v. If you need to, you can add a transistor cct to buffer to your keyer. Mine works fine. Mount the 2 9v battery holders one on top, one on bottom of the cct board. you can put the battery in one and the laser in the other. To test: point laser to ceiling. Move it back and forth quickly while holding the key down. You will see dashed lines instead of a solid line. You can even "see" the duty cycle! This was discovered by my daughter! - - - - - TOGETHER? You can put the 2 pieces in a case, but... beware the rx picks up the 555 oscillation. Best to encase the RX in an alum case OR since we are cheap, aluminum foil (with a wire to the cct board ground). Be sure to leave a hole for the phototransistor. AIMING? Handheld is almost useless. A camera tripod is good. For practice go to your local car parts store and look for DOT-90 reflectors. They have sticky backs and you can get a great return on them (about $4). Or head to the junk yard for reflectors off cars (thunderbirds have GIANT ones in the rear lenses (a few years ago). Bore sites seem very good. I mounted a 1/8" ID tube to my laser. I site thru it. Works good in daylite, but problems at nite, unless there is a light source at your target. Lots more to be written on this subject... LATER! CLOSING DO IT! I need contacts in JUNE from UC Santa Cruz, CM87xx! Jim WB9AJZ/6 Sunnyvale, CA CM87xi jmoss@berlioz.nsc.com