The Jim Patchell Archives of DIY synth stuff

    This is a collection of stuff that I did a long time ago.  It is going to take a while to fill this in, because as I found out this first night, scanning documents is not easy.

     Paia 4720 Exponential Conversion

        This is a circuit that I had originally wanted to sell as a kit.  Problem was, by the time I finally got around to finalizing it, around 1983, I found out that Paia had discontinued the 4700 series synth, which took the wind out of my sails real fast.  It never went beyound a breadboard test unit that I did.  I should still have that around here someplace.  If I find it, I will post a photo of that too.

     Using the Ideal Diode

CA3280 Stuff

     Analysis of CA3280
     Distortion comparison 3280 vs 3080
     Gm as a function of Diode Bias Current
     Maximum Input Voltage vs Id for constant distortion
     Current Sources for the CA3280
     Voltage Controlled Amplifier
     Voltage Controlled Glide
     Filter Circuits
     Sample and Hold Circuit
     ADSR Circuit
    Balanced Modulator

Photos of ancient History
     Old VCO Board
     Old Voltage Controlled Filter
     Old VCA/Mixer board
     Old Envelope Generator
     Old Hex Addressable Sample/Hold board

Keyboard Encoder
     Old Keyboard Encoder

Addons to Paia Kits

    This first one is a memory/IO expander.  I used to sell these.  It was my biggest mover (which isn't saying much, I sold about 16 of these).  It has 1K of extra RAM plus two 6522 VIA's for I/O and timer functions.  As of this posting, I have two blank boards left.  They are up for grabs.

     Memory Expander for Paia 8700 micro computer.

    If you have any questions about any of this material, you can email me......  email me

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