The Jim Patchell Synthesizer D.I.Y. Web Page
This website was first posted in December of 1998.
Last updated Feb 24,
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.
|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
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.|
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++|
||This is a Library of both parts and Circuits that can be used to make synthsizer functions.
Electrical Engineering Resources
I'm a Maker, You can be a Maker TOO!
I'm a Maker, You can be a Maker TOO!
Sources for making projects.
Sources for making projects.
They offer parts for making linear stages and CNC machines.
They offer all sorts of goodies, including 20mm extrusions, linear motion systems and CNC
They offer a wide selection of parts, boards, modules, hardware, etc.
Synth Module Boards
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...:-)
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.
of the OTA
Spindle Controller and Spin Stand
My First Synthesizer Project
Old Data Sheets
Synth DIY FAQ web page
Protel PCB Utilities
Polyphonic Synthesizer Boards
Control Voltage Splitter
Roland MT32 firmware mods
Transistor vbe matcher
Seven Segment Decoder Pal
My Home Studio
Voltage Controlled Vocal Filter Experiments
Archives of some old drawings and articles(new)
DIY Digital Synthesizer page
Picture of Various Things
This is a collection of some of my music. I am a Joplin fan, so that is what I tend to do.
Entertainer by Scott Joplin (MP3)
3. Elite Syncopations by Scott Joplin (MP3)
4. The Cascades by Scott Joplin (MP3)
5. The Chrysanthemum by Scott Joplin
6. The Great Crush Collision March by Scott Joplin (MP3)
7. Maple Leaf Rag by Scott Joplin (MP3)
Equipment used (sorry, old recording, no SYNTH DIY in this one):
TX816, Yamaha TX81z, Yamaha FB-01, Kawai K1r, Oberheim XK controller,
SPX90, Teac 40-4, Art 2408, Marantz PMD430. Digital Mastering
an Echo Layla. Midi Sequencing Atari Mega ST4 running Cubase
The Literary Section
Santa Barbara Atari Computer Enthusiasts (SBACE)
Yep, I own Atari Computers.
Atari ST Files
Anyway, all for now. Hope to hear from you all.