Having recently acquired some LCR0202 vactrols on the cheap, I wanted to give the Quackmire a try on vero. Unfortunately the few layouts I found were pretty messy and wouldn't fit the vactrol formfactor. I also wanted to add a few controls to it, so I decided to make my own layout.
My version of the circuit is slightly modified for bass, though it sounds OK on guitar if you don't mind it being a bit swampy. First, my edit of the original schematic:
Changes here include:
- C5 upped to 330pF
- Drive pot added to the filter op-amp. On the schematic I have 500k because that worked well on the breadboard. On my actual build I dropped it dramatically to 10k because anything more than that caused oscillation. YMMV.
- C11 was added in parallel with the drive pot to tame clipping harmonics.
- An attack pot was added after R12. 2k seems to be plenty here. 5k was kind of fun, but killed the effect on some Sense/Range settings.
- The volume pot was replaced with a fixed 100k resistor. The effect is "close enough" to unity for me.
- Not noted in the schematic, I added a switch to put a 47uF cap in parallel with C10 to smooth out the envelope.
Now, the layout:
There wasn't a good symbol to use for the LCR0202, so in reality it doesn't go that far past the legs. The dot on the 202 is on the negative leg of the LED side, so that needs to be in the upper right as explained in the layout.
I have built this just as shown and it works, so it's self-verified. Feel free to ask any questions or offer suggestions.
Modified Eye of Goat Quackmire using LCR0202
- lykwydchykyn
- Breadboard Brother
- lykwydchykyn
- Breadboard Brother
Oops, found some errors in the layout. Here's a fixed version: