K3PTO Published Articles
Last Update: 17 May 2017


Assembly Language Essentials -
Book published by Circuit Cellar in May, 2011
Link to the Circuit Cellar web site for the book  This promotion code will get you a 15% discount:
LC15EXP0531 ( not sure if this is still good :) )

The book is targeted to meet the needs of anyone who does not know Assembly Language but would like to learn.  The only precondition is that you know, or are familiar with, at least one other programming language.

The book develops a fictional processor with its own architecture and instruction set.  This was done so that the reader does not need to be familiar with an existing CPU.  I have written an assembler for the processor that you can download here along with a number of sample programs that are discussed in the book.  This file contains the current errata for the book.

Magazine Articles

Due to an error on my part, I have had to slightly change my username at OshPark.  Please note the change below.  My call must be in upper case.

Any of my articles which use circuit boards available from Osh Park can be found at this url: https://oshpark.com/profiles/K3PTO

A Digital Analog Part 1 - Replacing a 555 with a PIC - December 2016 Nuts and Volts

This article describes an implementation of many of the features of a 555 using a PIC microprocessor.  The source code and a schematic can be found here.
This is the first in a series of five articles which will review the 555 and 556 circuits from the book:  

Engineers Mini-Notebook 555 Circuits by Forrest M. Mimms,III ©copyright 1984, see also: http://www.forrestmims.org

A Digital Analog Part 2 - Replacing a 555 with a PIC - May 2017 Nuts and Volts

This article discusses those circuits of the Mims book that are used basically as a monostable multivibrator.  The source code, schematics and pictures can be found here.

Toilet Sentinal - October 2016 Nuts and Volts
This article describes a small PIC-based project which sounds an alarm if your toilet tank does not fill by the time it should which indicates a fault condition - probably a leak.

Here are the files for the project.  The PCB files can be found at https://oshpark.com/profiles/k3pto.  The project name is  Toilet Sentinal.  

PIC Dip Meter - July 2016 Nuts and Volts

I have a few sets of PCBs on hand for this project.  Please email me if you would like a set: 1 main board and 6 coil boards.

This article describes a PIC-based Dip Meter with a digital frequency display.  The unit covers six bands from 1MHz to 60MHz using plug-in colls.  All construction files are available here: PIC DipMeter Files.zip

The PCB files can be found at 
https://oshpark.com/profiles/k3pto.  The files are: DIP Main and Dip Coil.  The unit requires one DipMain board and six DipCoil boards.  Since OshPark requires that you purchase boards in multiples of 3, I am willing to purchase the boards from them and resell them in single piece quantities at cost plus mailing.

PIC Audio DDS - June 2015 audioXpress magazine
This article describes a PIC-based audio DDS signal source.  It is menu driven via a 4 line LCD, Quadrature Encoder and Joystick.  Several modes of sine wave generation are available: continuous sine wave, sweep, and frequency list.  All construction files are available here: PIC Audio DDS Files.zip

The PCB files can be found at 
https://oshpark.com/profiles/k3pto.  The file is: PIC Audio DDS.  Since OshPark requires that you purchase boards in multiples of 3, I am willing to purchase the boards from them and resell them in single piece quantities at cost plus mailing.

Wall Wart replacement - April 2015 audioXpress magazine
This article describes a quadruple wall-wart replacement power supply.  The voltages can be set individually between 5V and 15V.  Each supply is capable of 1amp but is dependant on the power transformer you use.  Each circuit board is designed to allow you to have an individual on-off switch as well as either of two types of voltage control - screw driver trim pot or "normal" front panel rotary potiometer.  All the construction files are here: WallWart-1.zip

The PCB files can be found at https://oshpark.com/profiles/k3pto.  The file is: WallWart.

Audio Spectrum Display - August 2014 audioXpress magazine
This article describes an Audio Spectrum Display that can be configured for ISO standard frequencies – those that typically are used for graphics equalizers. This system uses sets of ten LEDs to show the relative amplitudes of bands of frequencies. The system can be implemented with essentially any number of frequency bands displayed.  All construction files are available here: AudioSpectrumDisplay.zip

The PCB files can be found at 
https://oshpark.com/profiles/k3pto.  The files are:  4xFilterL  and  Pwr-PreAmp.

TwinTee Oscillator and Dual VU Meter - January 2014 audioXpress magazine
Build an instrument that will aid you in debugging and testing audio systems.  The unit consists of a high purity, single frequency, sine wave and stereo VU meter.  The amplitude of the sine wave is adjustable up to +4dBu and has two fixed attenuators which may be selected.  The VU meter has a nominal full scale of +7dBu and has two selectable fixed gain values.  The unit can be powered with an internal 9 V battery or an external power supply.  All construction files are available here:
  1. DipTrace files
  2. Figures and docs
  3. PCB gerber files
I have spare PCBs.  Please email me for details.

Function Generator - Jan. 2013 Circuit Cellar
Build a function Generator which has simultaneous PWM (Pulse width Modulation), PPM (Pulse Position Modulation) and DDS (Direct Digital Synthesis) signals.  It is controlled by an RCM5600 from Digi International
(Rabbit Semiconductor).  The generator uses a four line LCD, a joystick and a quadrature encoder to navigate the menu system and to select the signal parameters.  The DDS has both variable amplitude and offset.  All construction and source code files are available here:
  1. DipTrace Files
  2. Dynamic C Files
  3. Figures
The Batch PCB job numbers are:
  1. Main Board: 100395
  2. DDS Board: 100401
  3. Switches Board: 100403
Calibrated db Meter - March 2010 Circuit Cellar
Measure the absolute level of an audio signal anywhere within the range of  -80dbm to 0 dbm.  The high end range can easily be extended by the use of  a selectable attenuator.
Here are the files you can download for this project:
  1. DipTrace source
  2. Documentation
  3. Circuit Boards
  4. Pictures

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

Note: the Mouser part number for C2 in both schematics is incorrect.  It should be: 140-RXJ221M1HBK1025P.  Thank you to KF5QNT for pointing this out.

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.

I am posting the design files here for anyone who wants them.  Please understand that it has been so long since I have attempted to use the CPLD files that I can provide very little help with them.  I can probably do better with the VB stuff.

Dso20031129.zip contains the DSO design files and a LOT of documentation.  It is abour 33MB

DSO_VB_20040509.zip has the VB code for both the DSO and SBLA.  It is about 250KB.

SBLA_Quartus.zip contains the design files for the SBLA and is about 650KB.

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