My First Synthesizer Project
First Posted June 7, 2004
Well, this project was started in 1973, or there
abouts. I was at Santa Barbara City College at the time.
The library there had Radio Electronics magazine, and I would go there
to read and do home work. When I saw the article on building your
own synthesizer, I was hooked immeadiately. This was, of course,
the legendary Paia 2700. Some of the circuits were build as is,
others I didn't like. The VCO was one of those. I used the
national semiconductor aplication notes for the LM324 to build the
voltage controlled triangle oscilator. Back then, I had no money
to speak of, so everything was pretty much built from salvage
parts. The LM324 was a free sample. They were not cheap
back then. I did buy some LM741/747/748 type opamps to make some
of the modules. All of the transistors were salvaged. Pots
were a very strange collection of pots salvaged from old radios (I
could kick myself for that misdeed).
I can't seem to find the VCA module...it is around
You should compare these modules with this one (my latest project).
Anyway, hope you enjoy the photos....
Band Pass Filter
Low Pass Filter
Digital Sequencer....Now, this was my own design (Paia never had
anything like this....)
The eight slide switches were used to enter an address. The ram
was 256 bytes by 4 bits. You would then press a button to latch
the address, then you would set the data word with the lower order four
slide switches, and push another button to latch the data into the
ram. When you were all done, you would flip the run switch and it
If you look below, the R-2R ladder network is plainly visible. I
could not afford to purchase any kind of DAC at the time. I got
quite a bit of use out of this thing. At the time, I had no audio
recording equipment, so there is nothing to listen to....