This is a digital snapshot of the oscilloscope display of a code practice oscillator keyed by a simple CMOS paddle keyer. The output is the same on both "dits" and "dahs", even though the "dahs" are supposed to be a lot longer.
Hopefully, it's obvious that the tall lighted regions are "key down", and the "horizontal lines" are "key up".
Any thoughts? Thanks -- KC9ASI.
The designer of this circuit, Mike Martell, said this:
Check pin 13 of IC 2 to see if it is going high when you touch the dash paddle. If it is, then trace signal through diode D4. Also check Pin 12 of IC 2. It should be going low when you touch the dash paddle. If it isn't then trace signal from D2. The circuit gives dahs by generating 2 dits through pin 1 of IC 1 and then generating a fill in dit through pin 13 of IC 2 to keep it high in the middle period to generate a dah.
Here's an enhancement idea for any simple keyer. Operating preferences for different people are, well, different. I prefer dahs on the thumb, where the rest of the world seems to prefer dits on the thumb. So, to facilitate use of my equipment by operators who may have the "wrong" preference, I added an "A-N switch". Here's how to wire it in:
(For those of you who think that it's silly to be building a $6 keyer when I've got a fancy oscilloscope like this, please understand that I got the oscilloscope for almost nothing ($25) and am still borrowing probes to use with it, because I haven't built my own yet.)
Now that I've gotten it fixed, here's what the scope picture looks like:
The problem: a missing wire from IC2-11 to IC2-1 made dits all the time, and ONCE in a while, I could trigger one dah that would not stop (minutes and minutes).
I also added a pulldown resistor across the base and emitter of Q1 (the output transistor). This improves performance when used with the RASON FM keyer. Before adding the resistor, I was getting tone all the time, with an increase in volume on key down. After, I get a clear "no tone" on key up, and "tone" on key down.