Found in Radio Electronics from the 90s, this circuit uses components from that time. However, it can still be elaborated with some ease.
This circuit is from Popular Electronics from October 0, 1981. The diodes can also be 1N4004 and...
This circuit was found in a 1967 Electronic Design. The FET is from that time. Capacitor C is...
We found this circuit in an old General Electric documentation. In fact, PUTs are not common...