[sdiy] Parts ID request

[John Loffink]

Right.

I checked the daughter PCB and it just has DC blocking electrolytics at the
input and output.  No anti aliasing filter.

Rectangular can has 8 filter legs to the all pass op amp + inputs.  The
other 4 pins are connected together and go to a circuit with op amp, NPN and
PNP.  Tracing this out now...

John Loffink
The Microtonal Synthesis Web Site
http://www.microtonal-synthesis.com
The Wavemakers Synthesizer Web Site
http://www.wavemakers-synth.com


> -----Original Message-----
> From: Harry Bissell Jr [mailto:harrybissell at prodigy.net]
> Sent: Tuesday, February 15, 2005 10:17 AM
> To: John Loffink
> Cc: synth-diy at dropmix.xs4all.nl
> Subject: RE: [sdiy] Parts ID request
> 
> If its switched capacitor it will have a clock.
> It would also have anti-alias filters (well it
> should :^).
> 
> If you suppose its an LED-Photoconductive cell, there
> should be an obvious drive for the LED... and you
> could meter across it and prove that (might need to
> use the voltage drop, depends on your meter...)
> 
> I don't think switched capacitor filters became
> popular
> until the integrated chips. You might switch with FETs
> perhaps...  but why pot that kind of module ?
> 
> H^) harry
> 
>