I stumbled on this while looking for flipflop octave divider circuits. I figured the 4013 dual flipflop would be fairly simple to use to get a sub-octave square-wave for when we want to fatten our oscillators and might make a good easy brAEdboard project for newcomers to DIY.
More generally, a guitar signal needs a little boosting to feed into the Master module's input. Any guitar pedal that ups the signal a bit would do (EG, fuzz etc.).
Using a guitar pedal as a module would need two converters: one to drop the AE 5v~ signal down to about 25mV~ for the guitar pedal, then another to take the output of the pedal and boost it back up to 5v~ to continue through the other AE modules.
I'm pasting this from the DIY channel on the AE Discord discussion:
My goal in this exploration is to make a re-usable circuit for connecting AE to and from other gear - just a simple Audio I/O/ The first board I make will be a stomp box adapter to press my old guitar pedals back into service as external modules for my AE synth.
I would like to use this circuit, pretty much as is, to convert guitar/stomp-box/other line signals for feeding to AE modules' audio inputs.
This is what I understand so far (please correct me where needed):
The signal from guitar or line-level audio source comes in through J3 and passes through a 1.5Hz High-pass filter formed by R1 and C1 to take out any DC in the input signal.
R5 R6 and C16 are a voltage divider to get 2.5volts from the 5v supply.
This 2.5volts serves as a 'virtual ground' and, fed through R1 to pin 5 of the MCP6002, offsets the input AC so 2.5v is now the centre around which the input sound wave, uh, waves, instead of zero.
C3 and R3 are across pins 6 and 7 of the 6002 in order to filter (low-pass 5.8kHz) out possible aliasing artefacts from the circuit's interaction with the Arduino's A0 dac input.
Q: Is there any point in having this here when getting input from a stompbox to feed to any AE module input?
RV1, along with R2 and C2, are basically the gain control to determine the voltage at pin 6 to tell the chip how much to embiggen the sound.
C4 and R4 filter out anything above 1.2MHz to remove any RF and make things a bit more stable.
C15 is a decoupling capacitor to reduce noise.
Note: the above circuit is for converting input from guitar/stompbox/line input (maybe mic. also?) to feed to AE modules. This would be the output of a stAEmpBox module.
I have not got to figuring out the input circuit yet - I assume it could be as simple as a voltage divider, with offset to make the line-level signal bipolar again but I imagine the 6002 may make an appearance here for a bit more precision?
I am also imagining that there would be two such circuits in a single unit module and that the send/return jacks would be stereo mini phono jack sockets so we can use a stereo-to-2xRCA cable with RCA-to-jack adaptors on the other end. The sockets would be reinforced like in other I/O modules.
robertlanger Is there anything you would add or remove, so far?
I know you talked about releasing one eventually - do you have such a thing on your release schedule already?