Hi.
I built the original Cave Dweller and skipped the Cave Dweller 2015, so I was really happy to see the new 2022 configuration. I hope you don't mind, but I've converted the schematic into a Vero layout for my own nefarious purposes, even though I was doubtful about pushing the voltage limit on the PT2399 above 5v. It works, though.
After building I thought it was a bit dark, so decided to use the various suggestions (change the 100K modulation resistor to 47K, change the cap in the op-amp across pins 13/14 of the PT2399 to 2n2, remove the 22n to ground for brighter repeats) to brighten it up, and I quite like it.
The MPF102's can be hard to source so I was thinking, since it's essentially a unity-buffer in a sort of cathode-follower configuration, the circuit could probably be reconfigured to use a MOSFET (BS170, say) instead, which is a LOT easier to source, but I haven't built that version yet because the pinouts are different and there's another resistor from gate to +9v to add, etc. I've got a Vero for that, too, though, if anyone wants to try it.
If it's OK, @madbean, I can post the Vero layouts, but I don't want to dilute your great work.
I built the original Cave Dweller and skipped the Cave Dweller 2015, so I was really happy to see the new 2022 configuration. I hope you don't mind, but I've converted the schematic into a Vero layout for my own nefarious purposes, even though I was doubtful about pushing the voltage limit on the PT2399 above 5v. It works, though.
After building I thought it was a bit dark, so decided to use the various suggestions (change the 100K modulation resistor to 47K, change the cap in the op-amp across pins 13/14 of the PT2399 to 2n2, remove the 22n to ground for brighter repeats) to brighten it up, and I quite like it.
The MPF102's can be hard to source so I was thinking, since it's essentially a unity-buffer in a sort of cathode-follower configuration, the circuit could probably be reconfigured to use a MOSFET (BS170, say) instead, which is a LOT easier to source, but I haven't built that version yet because the pinouts are different and there's another resistor from gate to +9v to add, etc. I've got a Vero for that, too, though, if anyone wants to try it.
If it's OK, @madbean, I can post the Vero layouts, but I don't want to dilute your great work.