This circuit was obtained from Motorola documentation. It generates light pulses at a rate of 120 per minute. Equivalent transistors can be used. The circuit can also excite high brightness LEDs.
This FM advertising suppressor (SCA) decoder circuit was suggested by Signetics in a 1980s...
We found this circuit in an old General Electric documentation. In fact, PUTs are not common...
We find this simple musical instrument in a 1977 Radio Shack documentation. The key resistors must be...