Running Eurorack circuits from 9v pedal supply?

[tatou]

Hi! I've recently been getting into modular synths, but since I already have an arsenal of guitar pedals I'm not letting myself get any effect modules, instead relying on ways of using pedals in my Eurorack patches.

To that end, I've been researching how to design things that bridge the two worlds, taking inspiration from the Boredbrain INTRFX & Transmutron, the Hungry Robot Modular pedal line, and various DIY "pedal I/O" circuits.

Those pedal interfaces can use Eurorack control voltage (and audio levels), but are powered by regular 9v negative-tip pedal power supplies. Any ideas how to accomplish that? One idea is a TC1044 charge pump for a bipolar 9V supply, and just assume you don't need the extra headroom that the standard +/- 12v Eurorack power supplies. Any other thoughts?

I already asked in a couple of modular synth forums and it's just been crickets...

Thanks!

[tatou]

To make things a little more concrete, here's a schematic for a pedal<>Eurorack interface (source) one might want to incorporate into a pedal enclosure with a 9v pedal supply ("TILE" refers to the Eurorack module):

[alanp]

Getting +/- 12V from +9V is problematic, depending on how much current you're pulling for the eurorack circuits. I just run my eurorack stuff in it's own rack, on it's own PSU, and run my pedals from a pedal PSU of some kind.

I've got a couple of CGS60 modules in my rack for pedal interfacing (essentially a passive voltage divider on the Send, to drop relatively hot Euro-signal to pedal levels, and a simple gain opamp stage on the Return to reverse the levels.)

[tatou]

Thanks for the reply alanp.

I realize that running +/-12v off of +9v, in general, is not a practical idea or solution (I have 2 small modular setups and a semi-modular that all run on their own 12-15v bipolar supplies). But in the spirit of DIY exploration (with some real practical applications), I'm trying to learn how this would be possible, or what the options are...

[alanp]

I'd advise pinging Juansolo -- his PS-1A builds make +/-12V from +9V to run the PS-1A correctly.

[tatou]

Dunno if this is from juansolo or not, but I did manage to track down this blog post which seems to address the question:
https://obsoletetechnology.wordpress.com/projects/studio-electronics/dc-dc-bipolar-power-supply-for-effect-pedals/

The tricks is a DC-DC converter, in particular a LT3467 chip (mouser data sheet). Appears to not be available in a thru-hole package, so tougher for DIY builds. But figure I'd share!

[Strategy]

I've messed with translating modular synth circuits to a pedal format. There are a couple of very small (relatively) bipolar supplies. Synthcube sells the Music From Outer Space Wall Wart PSU, I've used it for this. An issue is that synth circuits expect higher than line level signals so you must amplify going in and attenuate coming out.
Note, the Wasp VCF (many versions) can be powered from +9v and sounds GREAT as a pedal. Very easy build, super musical, using all standard parts.
Strategy