u/incanmummy12

So I’ve built part 2 of Moritz Klein’s VCO series on my Erica Synth Labor, and everything appears to be working, but I’m running into difficulty connecting my sequencer. I’ve tried using the KB output on my Mother-32, as well as the pitch output of a Keystep Pro, and neither have worked (I also just tried gate outputs to see if I could get any signal, but to not avail).

I’ve got the output plugged into a 3.5mm audio jack, and I’ve got the ground pin tied ground and the tip going into the input of my transistor. I’m using a BC547C transistor instead of the 548C he uses in his video, but other than that everything should be there same.

I’ve also tried changing out the resistor value in the voltage divider from the 4k he uses.

Any ideas on what I could be doing wrong?

EDIT: I didn’t have the TL072 inverting input tied to the output. That fixed it

I’m using the Erica Synths Labor to build a VCO, following along with Moritz Klein’s videos, and while I’m only on part 2, I’m not getting any signal when I plug it in. If I plug straight out of the Schmitt Trigger then I get a signal, but once I built the rest of the circuit and hook up the output from my voltage divider, I get nothing. I’ve changed out all the components including the TL072, but no dice. I also originally didn’t have the TL072 input 2 tied to ground, but it doesn’t seem to matter either way. Also FWIW I had this same problem for the part 1 build, before I added the transistor and potentiometer.