Maestro/Oberheim FSH1 - Expansion Mods ?

[Rectangular]

I'm interested in adding some extra options to my Maestro FSH1, its the moosapotamus version with Tonda's mods. I'm looking for a way to add CV-In (so I can control the filter portion with an outside control voltage. from what I understand, R22 is the likely input for this ?

secondly, I wanted to add a CV output for the S&H section, so that I can use the S&H voltage to control other effects. I'm guessing the output of Q6 or Q5 is where I should be tapping ?

I'm  not sure how plausible these are, or what kind of potential noise might be added by doing it, but I'd like to give it a shot. take a look at the schematic and see what you think: http://www.generalguitargadgets.com/diagrams/fsh1asc2.gif

-Rec

[Paul Perry (Frostwave)]

Yeah, Q6/R31 junction is where i expect the random voltage steps could be picked off. But you might want to have 1. adjustable level and 2. some voltage offset, or it might not be exactly right for wherever it is going.
And yes, i think the external voltage would go via a resistor to the emitter of Q3. The idea is, the external voltage goes via a resistor to generate a current that goes to the Q3 emitter. depending on the voltage range, you might wnat more or less resistance. And there is the offset to worry ablout as well.

[Rectangular]

I had to fish around a bit, and add a few trim adjustments, but I got the CV ins/outs working today, very nice in tandem with a moogerfooger. this noise transistor is really picky ! I need to try more NPNs...

thanks perry

[Paul Perry (Frostwave)]

I've never been happy with having to hand pick transistors for white noise generator circuits.
I just came across http://www.ascotti.org/programming/side/soundboard/sound_noise.htm
A digital approach using two cheap & easy to get chips. I expect it would run at other voltages without a problem (unlike the traditional transistor breakdown method). DISCLAIMER: havn't tried it yet - let me know if you do!

[paulodobay]

I had to fish around a bit, and add a few trim adjustments, but I got the CV ins/outs working today, very nice in tandem with a moogerfooger. this noise transistor is really picky ! I need to try more NPNs...

thanks perry

Hi, Rectangular!
I´m planning to use the Invisible Touch (http://topopiccione.atspace.com/PJ16TPCInvisibleTouch.html) to control de FSH-1 filter CV in, but I´m having a hard time to find the best point to do it.  Could you share your final word about it?
First of all, thanks for your attention!!
Cheers!

Paulo

[alex frias]

Very good ideas!