The Jim Patchell DIY Analog Synthesizer Webpage

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The Jim Patchell Synthesizer D.I.Y. Web Page

This website was first posted in December of 1998.
Last updated October 29, 2018

Description: Picture of me Welcome to my do it yourself analog synthesizer page. It is a bit more than that, but this is the primary purpose. I have been building my own analog synthesizers since 1974. I originally started building the circuits that John Simonton (Paia) published in radio electronics, and I started right in on trying to improve on them. My first wholly scratch built synth was completed in 1978, and I guess you could say I started out big. It was a four voice polyphonic synth. The keyboard scanner was originally implemented using my Polymorphic 8813. Soon, I changed over to using the 6504 micro processor.
I stopped for a while, right around 1990, partly because of the nice digital synthesizers that were available then, and even nicer ones now I have to admit (I love my Nord Modular), and also, because no body seemed to care about analog any longer, let alone, building one yourself. That has all changed now. Interest in analog synths is back up, and now that I have been introduced to the Internet, I have found out there are a lot of other people out there who share my interest.

Things are a lot different now than they were. It seems that finding the custom chips from CEM and SSM is very difficult. And besides, I don't like to design circuits that use parts that may become unobtainium. It costs a lot of money to make a PCB, I don't want to have to throw them away because I can't get parts.

I have started to design a new set of modules. This projects is now pretty much complete. There are still a few things that need to be fleshed out, but it is now a fully working synth. Hopefully, soon, I will be able to do a piece with it.

Plus, I hope to restore some of the old equipment I built a long time ago. I have three synths and a vocoder that are full of spider webs.

Some of the other things you will find on this website are lots of C code. One of my current projects (as of April 2010) is that I am attempting to write an ACTION! cross compiler for the Atari 800 computers. This also involves the use of Anagram, a Parser Generator. It was quite a challenge to write the parser, and I am pretty proud of the fact that I managed it despite the fact I have lost most of my eyesight back in September of 2010.

I am still praying for the return of my eyesight, along with my very loving wife, and many of my friends. But life goes on. My next project will involve making a softcore for the 6502 (like we need another one).

You will also find things lke real time operating systems, recipes for glutan free food, pictures of cats, paintings, music. etc.

Everything I am creating will be open source.

My Facebook Page

Things I am currently occupying my time wityh

August 4, 2012

Updated December 18, 2012

Activity	Comments
Taking care of my wife while she undegoes chemo therapy	This started in June of 2012. She finished with the Chemo Therapy at the end of September, and then started Radiation treatment. She finished the Radiation the first week of Decmber. She now just has to heal from that, and sometime early next year, she will start the hormone treatments. Update: It is April 2013 and we are anticipating the start of the Estrogen Inhibitor Therapy. The oncologist says that this is the most important part of the treatment. There are still a few hoops to jump thourgh before that can start.
Writing an ACTION! compiler	I have been working on this off and on since 2010. Still not done. Right now, I am mostly working on the assembler and the linker. I decided I need to get these two items working before finishing up the comp-iler since how they work may influence some of the features of the compiler.
Converting the original ACTION! manual into a Microsoft WORD document.	This is part of the above project. I aquired a copy of the action manual that was in pdf format, but it was from a scanned copy of the pages. This means that my screen reader won't read it. So, I decided to use an OCR program I found to convert the text in the images back into text, and now I am editing those in a WORD docx document. So far, I have spent about a month of spare time working on this, and I am about 1/2 done. As soon as I am done, I will post it as a standard PDF, DOCX, and Kindle file. Completed August 17, 2012
Animation	I am gathering the materials so that I can do a claymation animation. I am planning to do an animation based on a short story I wrote, and that you can find on this website, called Pixies and Nazis. I have a program called Claymation Studio that I am going to use to do the animation. I am going to try to use my regular camera instead of the cheazy video camera that came with the program. I am also going to shoot it on a miniture theater stage that I am going to build, soon.
Cheezy Synth Module Board	This is a syntheizer project I have been working on for a few months now. It is going to be a complete monophonic synth on a single board. It will include 2-VCOs, 1-VCF, 1-VCA, 1-ADSR, 1-Glide, 3 Drum voices, 1-Cymbal voice (very cheesy) and a Midi to CV converter. The Midi to CV converter is going to be based on the Atmel ATmega2561 AVR microcontroller. This part has 256k of FLASH, and 8K of RAM.. One of the things I am going to try and do is make this thing Arduino compatable.
CNC Machines	This is something I have had an interest in for a while. There is a lot of open source stuff out there to do this. Although, I am not sure just exactly how good some of it is. I am researching at the moment. Making the linear stages is going to be the most difficult thing, probably, and then trying to figure out how to ballance everying. You need to make sure you get the center of gravity in the right place. Update: I have learned quite a bit since I first started looking into this. Here are some links that you may find useful. 1. Adafruit Industries Adafruit has a lot of useful stuff for making small CNC machines. They carry both 20mmx20mm aluminum extrusions and 15mmx15mm aluminum extrusions that can be used to build the frames. They also have linear bearing systems and motors, pullys, plates, etc. 2. Open Builds OK, these guys really seem to know what they are doing. They make what I would call a complete systems of parts. One of thir up and coming products is called V-Slotl, which is a 20mm aluminum extrusion with a built in V slot that can guide stages. What is nice about this is you can build a system with a much lower expense that normal extrusions. At their store they are stocking up so that you will have a one stop place to shop for parts to make machines from.
Book Scanner	Book scanners are something I am interested in as well. I found a very nice open source book scanner on the web. Although, I am not really too sure how open source it really is. The plans are very bad, and the sape of the parts is very complicated. They were designed to be cut out on an NC router. This pretty much means you have to buy what seems to me to be a very overpriced kit. Again, I am doing a bit or reasherch to see what may be possible.
A Set of Chimes.	It is April 4, 2013, and I have been working off and on for a couple of weeks now on a set of chimes. My first set is going to be made out of EMT. Big Mistake. This stuff is hard and that makes it difficult to work with. So far I have the C5 pipe cut and tuned. The F5 pipe is still a bit flat. Taking metal off these things is not easy.
Disney Pump Organ from the Snow White and the Seven Draves.	Ok, this is just plain silly. Down below you will find a link to my page where I express my desire to do this. But I am actually in the planing stage. First off, the instrument as illustrated in the cartoon can't possibly work. But, that is what makes it such a challenge. I am going to use the metaphore of an Analog Polyphonic Synthesizer to make this thing work. My plan for right now is to have 6 pipes that are basiclly going to just be recorders. The holes will be covered by flaps carved to look like hands and the holes will be surounded by the face of a drarf. Each pipe will only be able to play one note at a time, but by using techniques similar to an Analog Polyphonic Synthesizer, I will have an instrument that will play six notes at a time. The animation of the hands opening up the holes should be hilarious, just as it was in the movie.
Open OTA	April 28, 2013 This is a project to create an open source Operational Transconductance Amplifier.
The Game Risk	November 12, 2013. This will be the first game I have ever written.
ATR8000	My project of reversing the ATR8000
FrontCAD	I am writing my own front panel design program. Here you can see my progress. You don't have to be crazy to write your own CAD program, but it sure helps.
Network Frequency Response Software	A guide to writing your own circuit analysis software in C++
KiCad	This is a Library of both parts and Circuits that can be used to make synthsizer functions.
JamCad	My latest sotware project. This is going to be a DIY EDA CAD package. For many years I have wanted to write my own EDA package. Taking what I learned when I wrote frontcad, I am plunging into the world of schematic capture and PCB layout. This is a massive effort. I expect to have written 250 source files before it is done.

March 2, 2012
Integrated Circuits that Changed My Life

    I read an article today about the 25 ICs that shook the world. I thought I would make a list of the ICs that were influential in my life.

    1970

            I wanted to build an UP-DOWN counter. Don't ask me why. In 1970 this seemed like a very big challenge. I was originally going to use discrete transistor flip flops and logic. But that was a lot of parts. Then I discovered the Motorola HEP series of parts, that included JK filp flops and NOR gates in a TO99 can. So, I built my up down counter. It was still a rats next of wires. But it worked. I have no idea what ever happened to that project, but I do still have the ICs If I could see the numbers on the cans, I would list the part numbers.

    1974 LM324

        I did a lot with this IC. The first one I ever saw was one my father brought home that he had received as a free sample. And the project that I did with this part? Why, it was a VCO for the synthesizer I was building at the time.

    1976 DG201

    Discovering this chip was a big deal. Four analog switches in a single pacage allowed me to do some really cool things. I have never been without them since.

    1976 CA3096

    This was a transistor array with 3 NPN and 2 PNP (lateral) transistors in it. This was my introduction to the OTA. I used these parts to make OTAs for filters and what have you. Somewhere, I still have a filter that uses these parts.

    1976 CA3080

    I soon discovered the CA3080, which was an OTA in a can. I started using this part instead of the CA3096 mostly because it was about 1/2 the price.

    1977 6502, 6504

    My first computer was a Polymorphic Poly88 computer. This was an 8080 based machine. And I used this as noted above to control my fist synthesizers. I always found the 8080 instruction set to be kind of clumsy. Then I read an article by John Simonton about the Paia 8700 controller, which I later bought. When I read the code listings, I realized that this was a processor that was designed to be programmed. At first I would assemble the code by hand, and punch the code into a 2708 EProm programmer that I got from JAMES ELECTRONICS (now Jameco). Despite the tortures of programming this way, I felt that the results were much better. I eventually ended up with quite a developement system when I purchased my Atari 800 and an Arium 4100b logic analyzer with a 6502 pod on it.

    1978 CA3280

    When I saw the ad for this part in EDN, I knew that this was going to be an important part. I got a couple of samples right a way, and checked them out. They were everything I could want, and more. I immediately found a distributor and ordered a 100 of the suckers. This is one chip I really miss. As many of you may know, it is no longer made.

    1985 MC68000

    When I was finally able to afford to purchase one of these chips, I thought I had died and gone to heaven. I eventually purchased, in 1989, the SDS Cross Code C for the 68000 and just had myself a lot of hacking fun.

    1992 XC4003

    This was the first FPGA I ever used. It had a wopping 3000 equivalent gates and it cost $275 at the time. I used it in a servo controller design I did for Teletrac. That got me in a love affair with FPGAs. Although, with my current handicap, are not easy to use.

    1998 AT90S8515

    This was the first AVR I ever used. I was at the time trying to decide between the AVR and the PIC, and the AVR won out for technical reasons. The AVR series is very easy and inexpensive to use. It is still my first choice for projects.

Electrical Engineering Resources

I'm a Maker, You can be a Maker TOO!

Sources for making projects.

Open Builds

They offer parts for making linear stages and CNC machines.

Inventables

They offer all sorts of goodies, including 20mm extrusions, linear motion systems and CNC

Sparkfun Electronics

       They offer a wide selection of parts, boards, modules, hardware, etc.

        AdaFruit Industries
            They offer a good variety of stuff. Parts, boards, modules, CNC.

    Mouser Electronics

        Mouser is a distributor that carries an extremely large inventory of electronic parts. This is the place to go if you need your parts at a good price and in moderate to high quantities.

    Digikey

           Like mouser. I use both places. quite often you can find something at one and not the other.

The following venders cater a little more to the Synth DIY crowd.

    Tayda

       These parts come from China. Good prices, good quality, so far, at least on every thing I have purchased.

    Small Bear Electronics

       They in particular have a good selection of pots. Good prices, Good Quality.

    Mamouth Electronics

    A good selection of parts.

    Ethervar

       These guys target specifically the Euro Rack builter. They don't carry very many parts at the moment, but what they do carry is very important. The have euro rails that can be cut to any lenght up to 300mm, rail mounting brackets, 9 mm pots, vertical 3.5mm mono jacks that match up with the height of the 9mm pots, and several other items. Check them out. I really like these guys.

    Synthrotek

    Again, these guys specialize in Eurorack. I have yet to make a purchase from them, but prices look good.

    Thonk

    Another Eurorack company. I have heard good things about Thonk, however, I have yet to make my first purchase.

Want to be added to this list? Send me an email.

Synth Module Boards

SMB1

SMB2

SMBC (Cheezey)

Blackmer Synth Module Board

The Arduino

Intrerfacing the Spartan 3 Starter Kit to an Atmel STK500/501 to make a Digital Synthesizer

Pacific South West Synthesizer DIY Meet on June 10, 2006

MS20 DIY Project

The Start of the DSM1 Digital Synthesizer Module

Pacific Southwest DIY Meet 2004 Photos

Pacific Southwest DIY Meet 2003 Photos

Synth Modules For Sale
Parts For Sale

Synthesizer Project

The Jim Patchell Verilog and VHDL Archive

Strobe Tuner Project

The Jim Patchell Gluten Free Webpage

Gluten Free Cookie Recipes

Windows Programming Examples

Building Odd Musical Instruments

DIY Audio Webpage

Mikado Analog Sequencer

Keyboard Encoder Project

Radio Projects

Interfacing Ethernet to Midi

Loss of my Eyesight

The Secrets of Compilers

Recursive Descent Parsing

Animation

Marion Systems MS68K Single Board Computer

The love of my life

Here are some photos from early outings I had with Noni...Now, on the first two, you will note, I did not take any pictures of Noni...I am not exactly sure why that was. These were pretty early dates...and I was still not exactly sure how Noni felt about me...I just don't know...:-)

A Day at the Botanic Gardens
A day at the Zoo

Walks With Noni

Well, in case somebody didn't know...I now have a very lovely young lady in my life. Noni Kimbel and myself are getting married on December 30, 2006 at the First Presbyterian Church in Santa Barbara, California. The Christmas party was very important. Because of my work, I was not able to go north to Seattle to celebrate the holidays with my family. The Kimbels were very gracious in sharing the day with me. Little did any of us know that a mere six days latter our two families would be joining. It was on December 31, 2005 that I proposed marriage to Noni.

Christmas Party 2005 with the Kimbels

Christmas Day 2005 with the Kimbels

It was, however, 10 days latter that I go the answer...
Noni Says Yes

And about two months after that Noni finally got her ring.
Noni's 50th Birthday