Breadboard module...why not?

So I built a high pass filter from Moritz Klein’s fully resonant vactrol vcf. I of course put it on breadboard first. Everything works great on the breadboard with resonance and self-oscillation. On to the strip board… It will not self oscillate. I removed the panel and hooked it up to the breadboard to test my panel wiring and such and the panel works with the breadboard with self oscillation. The strip board will not self oscillate. I checked and rechecked and rechecked and rechecked to the point to where I threw the strip board away and built another one and got the same result. LOL. No self-oscillation on the strip board. The filter still works great. The resonance still has an effect, but no self-oscillation. I decided to keep it anyway. However, I am going to build another panel and wire it up directly to the breadboarded circuit. I’ll be able to change up the format by moving a few jumpers to make it a low pass filter anytime I want. There is no way in hell I’m going to build it a third time…ever.:100: lol. Anyway, I wanted to build another lpf as well and now I REALLY don’t want to… particularly if I end up having the same issue. It is maddening. :roll_eyes::crossed_fingers::grimacing::neutral_face::zipper_mouth_face: This has been another ranting random gripe from a FNG…thank you for listening.

1 Like

The right size. I may never solder anything again…:roll_eyes::rofl:

My next sequencer will most likely stay on the breadboard, anyway…

It might look easy but one day you will need to move your case and half of your modules will stop working. The most likely reason for your stripboard circuit problem is that there was a “mistake” you couldn’t spot.
I am using protoboards (same layout as a breadboard) maybe you could try it.


Some people love stripboards, some can’t stand them. I’m not a big fan. There are definite differences in soldering up stripboards versus single pad or breadboard-style protoboards versus fabricated PCBs (and I’d guess home etched PCBs are yet another thing) and what’s naturally easy for some builders is painfully hard for others. If stripboards aren’t working out for you, maybe try one of those others.


I like strip board all right. I like the format. I like building on it. I don’t like protoboard so much just because of all the jumps. I’m not done soldering for good, i just got super frustrated with not being able to figure that selfoscillation out. Both the filters have unique characteristics tho. The one on strip board seems to have a brighter sound but the one on breadboard resonates like a mother! I like them both.

I tried so hard to find that mistake! Seriously I had to throw the first one in the fire dude no doubt. I burned it so I wouldn’t have to look at it anymore! :fire::joy:and then I started from the bottom up with another one got the same result, and I still couldn’t find the mistake. :grimacing::zipper_mouth_face: I have to agree with you though there must be a mistake in there somewhere I just gave up on trying to find it. Both filters sound dope.

1 Like

It seems an update is in order. I can now get the highpass strip board module to self-oscillate as it should. Nothing about the module’s circuit has changed. I’ve eliminated a module or two on the power source, and I’ve “improved” :grimacing: other circuits in the rack on the same source, but those are the only changes. :thinking: I’m finding it difficult to resist the urge to modify it with some switches to have clipping and low pass output and better cv as discussed elsewhere by me in this forum. Anyway…:robot::fire:

Well, I went ahead with the modifications. I put a 47k resistor on the vactrols led instead of the 10k, and got a much better cv response. I used a dpdt switch to get the lowpass and it worked when I tested it, but the self oscillation stopped again. :neutral_face: So since I already had the circuit out and had been cutting on it I went ahead and lowered the resistance to ground in the feedback loop from 6.8k to 2k and got self oscillation with loads of resonance! With the clipping diodes switched in it mellows it out nicely. So the whole module is greatly improved. It’s my new favorite piece. Big fun. I put the Moritz Klein Sample and Hold on an Atari punk console and put it through the lowpass without the clipping and the result was fantastic! :fire::robot: Next I will be modifying the S and H…

Lowering the resistnance to ground on the resonance feedback opamps inverted input to 2k will definitely make it self oscillate. Adjust to taste or install a trimmer…:grin:

1 Like