Any others ?
I'll order the NSL32.
The red diode and cadmium sulfide photocell from RS got it working.
I should read up on my chemistry, no big deal, tryin' out various LED"s and currents for a while.
What color goes well with Cadmium Sulfide ?
Should I try a super-bright LED ?
Otherwise the circuit is stock except the 1meg instead of 3meg gain resistor.
I dropped the 4k7 Current Limiting resistor to brighten up the LED, squish down on the gain even more.
Works !
The red LED [through some paper] in the dark room sure seems like it could get brighter yet, I'm not sure what the spec-change to NSL-32 would do, I imagine faster response, right now it probably sounds 'sluggish' in ramp-speed times, pretty cool sound !
The 47uf cap looks like an interesting place to vary value/response, I'm not sure going much bigger would be a good idea, going smaller I think would reduce the time it takes to fill 'er up, and would make for shorter blinks.