Ring modulation: CA3080 circuit???

[Colin Fraser]

On Nov 11,  5:19pm, john.. wrote:
> Subject: Ring modulation: CA3080 circuit???
> 
> this is just going to be a `warm-up' project - I'm going to build a set
> of analogue drum-voicing units (from the 808, 606, CR8000, 909)  and put
> them in a box with my MIDI-Trigger converter for a `real' drumstation :)
> 

This is one of my current projects too.
So far I have a 4 unit rack mount case with the front panel drilled for a full 
set of 808 and 909 sounds, with individual outs for each, master volume and 
power switch. The rear panel has stereo outs, digital (midi - at the moment) in, 
 power connector, and a multiway analogue out. 
Inside is a mass of circuitry, and it's not finished yet...
The bottom level of three houses a 6502 based processor board, which has a DAC 
and 40 way cv output multiplexer. 24 cvs are for drum accents, 16 go to the 
analogue output - this thing is my cv convertor too.
Another board has 12 74ls123 monostables to provide the 24 trigger pulses for 
the drums.
On the next level is a complete set of 808 sounds, identical to the real thing, 
except for the clap / maracas, which I added an extra output stage to so I could 
trigger them at the same time.
The top level will house the 909 sounds. So far I've built the bass, snare, clap 
and rimshot. Work will start soon on the toms. To build the hats and cymbals I 
need access to a real 909, to copy the sample roms (unless someone out there has 
a copy already...)

This project will take you ages, will involve a MASSIVE amout of soldering and 
have you jumping up and down like a loony when you finally get a 'real' drum 
pattern running on it.
BTW there are a couple of errors in the schematics for the 808 and 909. There 
are mistakes in both of the clap circuits but you can work out how they should 
be by comparing the two, as they are virtually identical. Others I can;t 
remember at the moment.
Transistor wise, you'll find BC182L and BC212L are good substitutes for the Jap 
transistors used in the 808.

Good luck 

Cf