The crazy project. First appeared in Popular Electronics 1971 and now an interesting arefact.
It's a sound/noise-machine that is propelled from a quasi-random genrator, a simple VCO, a VCA and a fixed filterbank. The original was built on RTL chips (Resistor-Transistor Logic) which now are pretty much unobtainable (or may be purchased at USD 10-20/each)
I had, once upon a time, the PCB made for me, got the ICs but never finished the build. Now I feel it is time to start again and I got the hard-to-find transistors but decided to look use CMOS for the logic.
I haven't seen any finished modernized Psych-Tones, but there are people showing their vintage ones. There
are however a schematic every now and then where the RTLs are replaced by CMOS.
BUT the digital circuitry isn't the only thing that can be improved. The VCO is made up of a UJT oscillator, but a more synth-like oscillator would do miracles, as well as an IC-VCA. Filters are a fixed filterbank, but cpuld be some kind of VCF.
OR, why not use the SN76477 sound chip I am using in the Linuphone ... But then it's not really a Psych-Tone any more.