Buchla Random Voltage Source - Convert to Eurorack?

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GKMendenhall
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Buchla Random Voltage Source - Convert to Eurorack?

Post by GKMendenhall » Thu Nov 19, 2020 3:09 pm

Hello everyone!

I've got my eye on building this Buchla random voltage source schematic as a eurorack module. Can anyone give me some advice on what component value changes I would need to make in order to make it work the same with +12V instead of the +15V listed in the schematic? Still pretty new at this...

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Re: Buchla Random Voltage Source - Convert to Eurorack?

Post by fluxmonkey » Fri Nov 20, 2020 8:58 pm

i have PCBs available for this: http://fluxmonkey.com/fluxmerch_buchla.htm. it runs fine on 12v without changes. the outputs swing close to the rail, though - i usually build mine with attenuators on the panel for each out, or voltage dividers behind the panel to bring them down to a more reasonable level.
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GKMendenhall
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Re: Buchla Random Voltage Source - Convert to Eurorack?

Post by GKMendenhall » Sat Nov 21, 2020 8:42 am

i usually build mine with attenuators on the panel for each out
Thanks!!

How do I add an attenuator for each output on the module?

I also have a PCB for an attenuator module, so that could work, too.

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Re: Buchla Random Voltage Source - Convert to Eurorack?

Post by GKMendenhall » Sat Nov 21, 2020 7:00 pm

I did some digging on this.

Should I just add a B100K pot right before the output jack and that's the attenuator?

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Re: Buchla Random Voltage Source - Convert to Eurorack?

Post by fluxmonkey » Sat Nov 21, 2020 8:25 pm

yeah, as a voltage divider:
Screen Shot 2020-11-21 at 8.24.11 PM.png
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Re: Buchla Random Voltage Source - Convert to Eurorack?

Post by 3hands » Sat Nov 21, 2020 8:36 pm

Forgive my ignorance, but is this not a Wogglebug?
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Re: Buchla Random Voltage Source - Convert to Eurorack?

Post by GKMendenhall » Sat Nov 21, 2020 9:24 pm

Forgive my ignorance, but is this not a Wogglebug?
No. The Wogglebug uses a different design.

This is just one clock in and four random cv outs.

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Re: Buchla Random Voltage Source - Convert to Eurorack?

Post by GKMendenhall » Sat Nov 21, 2020 9:25 pm

yeah, as a voltage divider:
Thanks for your help!

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Re: Buchla Random Voltage Source - Convert to Eurorack?

Post by mritenburg » Sat Nov 21, 2020 9:38 pm

GKMendenhall wrote:
Sat Nov 21, 2020 9:24 pm
Forgive my ignorance, but is this not a Wogglebug?
No. The Wogglebug uses a different design.

This is just one clock in and four random cv outs.
The Wogglebug is based on the Buchla 265 source of uncertainty, just FYI.

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Re: Buchla Random Voltage Source - Convert to Eurorack?

Post by fg » Sun Nov 22, 2020 2:14 pm

hello,

the "portamento" function is probably possible with this circuit ?

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Re: Buchla Random Voltage Source - Convert to Eurorack?

Post by GKMendenhall » Mon Nov 23, 2020 5:41 pm

hello,

the "portamento" function is probably possible with this circuit ?
Thanks for the Idea! I think I'll give it a try!

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Re: Buchla Random Voltage Source - Convert to Eurorack?

Post by MOOGi » Mon Nov 23, 2020 5:54 pm

If it works not properly with only +-12V use two Step_up converters which can change the +12V to your +15V

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Re: Buchla Random Voltage Source - Convert to Eurorack?

Post by MOOGi » Mon Nov 23, 2020 6:03 pm

and the second Step_up can change the -12V to your -15V

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