K3PTO Published Articles
Last Update: 25 August 2009
Four output Switching Power Supply - August 2009 QST and 2010 ARRL Handbook
This article describes the theory, circuits and
construction of a four output switching power supply. As
originally built, it had four positive outputs: two fixed and two
variable. I modified it at the request of ARRL and replaced one
of the fixed supplies with a negative supply. Any combination of
the supplies can be fixed and/or variable up to about +20V for the
positive and -20V for the negative regulators. As with my other
articles, the circuit boards can be purchased from FAR Circuits. All of the construction files are on the ARRL web site.
Here are the files you can download for this project:
1) Dip Trace source
2) Documentation
3) Circuit Boards
4) Spectrum Analyzer screen shots
5) Original text and files of article
6) List of all the files
Audio Spectrum Analyzer - August 2008 audio Nuts and Volts
This article describes the construction and operation of a configurable
audio spectrum analyzer. The main components are: a 132x64 pixel
graphics LCD, four momentary switches to select menu options, power
supply, audio processing circuit and microprocessor. The program is
written in a dialect of C and consists of several library files and the
main program file. There are three printed circuit boards which can be
purchased as a set from FAR Circuits.
CAUTION: the LCD interface board has a very closely spaced pattern (10
mills). This would not be a good choice as a project for someone who
does not have the capability to handle small circuit board spacing.
Here are the files which you can download for the project:
1) Original Text of the Nuts & Volts article
2) Source code for the program
3) A Readme text file containing a list of all the files
4) Schematics
5) PCB files for Silk Screens and Vias
6) Pictures of the boards
PC Audio Mixer/Distribution Amp - Oct 2007 Nuts and Volts
This is the PC Audio system add-on as published in the October, 2007
issue of Nuts & Volts. Although the system was specifically
designed to be used with a PC it can easily be used with almost any
audio system to expand the line level inputs and/or outputs. This link (about 4.5MB) will download the text of the magazine article including schematics. This link (about 3.4MB) will download some helpful construction information: board layouts, BOM, etc. Here are updated Construction Tips (about 2K) and BOM (about 18K) files.
Direct Digital Synthesizer - Nov 2006 Nuts and Volts
The DDS as published in the Nov 2006 issue of Nuts and Volts. This
device allows you to create a synthesized sine, triangle or square wave
of any frequency between 1Hz and 10MHz in 1Hz steps. Click here
to download all the files, about 4MB. The PCBs area available from Far
Circuits. Feel free to email me if you have any questions.
Please note that the link for DDS information in my article seems to have expired. Here is a new link - found by one of my friends - thank you Kevin!.
Another link from Analog Devices.
Here is another page which has a links to more tutorials.
I can no longer support
the following two projects because the CPLDs are very hard to get
and I no longer have access to the programmer. Also, the
schematic and PCB program I used (WinDraft) is no longer available.
Let me know if you would like the CPLD and/or the VB
source files.
Single Board Logic Analyzer - October 2004 Circuit Cellar
Updated 21 May 2005 with version 1.4 of DSO_LA
and help files. It contains improvements, described in the help file,
and an updated Read_me file specifically for the SBLA. I am leaving the
original files here just in case anyone requires them.
Here are some pictures from one of the users of the SBLA.
Updated 9 Oct 2004
This is my Single Board Logic Analyzer as
published in the October 2004 issue of Circuit Cellar magazine. Its
design is based on the DSO/LA which is described below. After designing
and building the DSO/LA I wanted to see how difficult it would be to
design a single board Logic Analyzer. This project and article is the
result. All the information required for building the SBLA is contained
in the file. The sample screen shots from the DSO/LA, minus the analog
portion, show the presentation of the SBLA. If there is enough interest
I will obtain printed circuit boards and purchase all the components
necessary for kits which I will make available for cost plus S&H.
The file _ReadMe.txt contains a list of
changes, a list of the files in the zip, as well as some construction
information. My email address is at the bottom of the page.
For anyone who is interested here is the latest version of the Altera files for the CPLD. Please realize that I no longer
have a valid version of the Altera software so I will not be able to
help you if you have questions on how to use it.
DSO/Logic Analyzer - July/August 2003 QEX.
Following is my DSO/Logic Analyzer as published in the July/August 2003
issue of QEX. Here is a brief excerpt from the article:
The device described in this article is a combination Digital Storage
Oscilloscope and Logic Analyzer. It interfaces to a PC via a parallel
(printer) port and is built using several printed circuit boards. The
system is designed such that it allows for 6 Input Cards. Each card can
be either 8 Logic Analyzer channels or a single Analog channel (8 bit
resolution).
Here are some of the main features:
1. Ease of construction - uses printed circuit boards
2. Multiple analog channels
3. Minimum of 20 MHz sample rate
4. Logic Analyzer channels
5. Trigger selection to allow various combinations of A/D and LA signals
6. Settable pre-trigger count
7. An initialization file which allows the user to define almost all of the operating parameters
This program is Freeware. Click here to see some screen shots.
Here are the necessary files required for the DSO/LA
Documentation (44KB)
DSOLA.exe and support files (484KB)
Screen Captures and Pictures of the DSO/LA (1072KB)
In the following zip files the ".ps" files are PostScript and the
".prn" are Laserjet4 formated files. All are double size. If you need a
different format please contact me and I will try to generate files
which are compatible with whatever printer you might have. I will also
be willing send hardcopy via SASE.
Board artwork (445KB)
Schematics (607KB)
I will be happy to program a PLD for you if you include an SASE. I
would also be happy to test the board as long as it requires no
assembly and you include a means of paying for the return postage.
Please let me know if you have any trouble getting any of the components.
If you have any suggestions for system enhancements or find any bugs
please let me know and I will try to implement them. If you run the
program and find something is missing PLEASE let me know and I will
update this site.
If you have any questions or comments, please feel free to email me at k3pto@arrl.net