This circuit was found in the March 1997 Electronics Now magazine. It uses a common analog indicator and the transistor is a general purpose one.
This amplifier for small cassette tape players was found in an English documentation from 1969. The...
This circuit is intended to trigger a TTL door or flip-flip from a signal coming from an SCR....
We find this circuit in a 1980s documentation. The circuit can be applied to modern operators with...