Is a 9v stomp box adapter circuit already a thing? Is it even possible?
Yeah there are a bunch floating around the internet I think. Here’s one by AI synthesis: https://aisynthesis.com/wp-content/uploads/2018/12/stomp-adapter.pdf
Looks to be running off of +/-12 volts though. I’m looking for something that can be powered by the same input as the pedal itself.
So you’re looking for a circuit that converts between eurorack and pedal signal levels while being powered off of 9V itself? Considering eurorack signals are usually 10-ish volts peak to peak, not easily. You could use a voltage converter like MAX1044 to generate a -9V rail in the box and then use a design like the AI one. Or if around 5Vpp is good enough for you you could also make one that runs just on the 9V.
Output to pedal just wants a reduced-level output like this: AUDIO OUTPUT – ShedSynth
Input back from pedal wants to be boosted back to Eurorack/Kosmo levels like this: INSTRUMENT INPUT – ShedSynth
The first one is passive but the second needs +12V/-12V power, which from your later message you hoped to avoid. You could try a simple +9V-powered amplifier and poke the output through a 1uF capacitor back to your modular.
Whichever you do, watch out for ground-loop through the power supplies &/or ground voltages actually being different.
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I’m not sure what you are asking for. Are you looking for a device that will attenuate signal levels from a synth to a pedal input, and amplify the pedal output to feed into a synth, and all powered by a 9V supply? If so, it would be surely simpler to have the device built into, and powered by, a synth.
I agree it would be easier - unless you have an excess of pedals!
I’m not saying I want to use them all at once - but at the same time it would be nice to have the option. That being said, from what I gather I would have to build an entire synth case & power supply to accomplish this so I’ll choose my battles, reign it in and figure out an alternative.
Not sure if this is at all what you are asking but I just did a video on the AI synthesis stomp box adapter, and made a list of the things about it that I think could/should be changed:
The way I have it implemented in my own rack is that I have a 9v power regulator pulling power from my synth case power supply, and I use that to power the guitar pedal that is in the send/return loop of the stomp box adapter. One less wall wart to worry about and I’ve not had ground loop issues yet. Just be aware of the amount of power those pedals are using.
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