Electric Druid Chips Test

If anyone finds the size that works, post a link

I tested them before building.... But it was luck. 
Normally all I do works this way: Sometimes you loose and sometimes the others win.  

I haven’t looked into that yet. I’ll get back into DIY once my new AEM cases and blank panels arrive. However, I just googled a bit and found a differential amplifier circuit, which acts as a voltage subtractor with offset. So a 0V input would result in a 5V output and vice versa, i.e. the input voltage is subtracted from 5V, basically inverting the signal and offsetting it to a 0-5V range (so not going negative).

In my simulation app iCircuit this seems to work. I don’t know about the best resistor values to use and just chose 50k ... maybe someone else has a recommendation for a better value? The resistors all have to be the same value though.

Here’s the circuit with a simulation result:


Again, the purple resistor values are just put in there without knowing anything. Haha. Results seem fine though.

The next consideration for choosing purple resistor values in this design would generally be ensuring that components aren't going to get fried from excessive current and/or power. For example, input pins on many op-amps must have the current sent to them be within the milli- or microamp range, outlined in its datasheet. In your case, a 50kOhm resistor facing the highest expected input voltage value of 5V, after simplifying into Ohm's Law (V=iR), would limit the current to the input pins to a maximum of 100 microAmps. I haven't looked at any Electronic Druid chip's datasheet, so I can't say determinedly if that's safe, but it probably is.

It's also possible to burn out those resistors if the power they dissipate is beyond their rated maximum. Power, P, given in Watts, dissipated across a simple resistive component, is given by P=iV. Assuming that no freak accidents occur, these resistors could see a 5V drop, and we've already determined that shoving 5V through a 50kOhm resistor in worst case scenario yields 100microAmps. So the resistors in your circuit could encounter up to... 0.0005 Watts. Many THT resistors have a nominal power rating of 1/4 W, which is five-hundred times greater than the expected load. I'm pretty sure those resistors will survive!

Generally, in the 0-5V world, 1/4W, kOhm-range resistors are going to survive most applications and keep other components safe. But it's important to check datasheets and determine these current and power values for each unique circuit.

Tl;dr: 50kOhm is pretty good for this circuit on this day with the sky this color and in this economy

Of course! Personally, I love the math, and anything else that helps to reassure me that I'm not going to burn my house down. 0-5V audio circuits are like Lego; they can be pulled apart and bolted together in fairly safe ways with the correct components. See a spaceship? Build a spaceship. Just not with low-value feedback and input resistors, or any direct shorts from V+ to ground

Awesome! I have the VCO in Eurorack format and it’s really fun with the two oscillators in one. Can’t wait to build my own!

A quick jam done yesterday, using VCDO's both oscillators. Other than that - for the drum sounds two T-Twin filters. For the sound processing used AE Modular's Delay and MultiFX + iPad for heavy post-processing compression, saturation and limiter.

List of used DIY modules:
2x T-Twin drums
2x ADSR's
1x Tap tempo LFO
1x VCDO
2x CD4069 chip filters
1x double 10step sequencer
1x step/frequency divider

List of used AE modules:
1x Wasp filter
1x Delay
1x MultiFX
1x 4Att/Mix