This circuit was found in a 1968 RCA documentation. The circuit can be designed with operational equivalents. Input signals can be up to 6 V in amplitude and the limitation is 78 dB.
This different configuration for a crystal galena radio or modernized since a diode is used, has a...
This circuit is from 1990 documentation. When we press D1 the lamp remains on for a time interval that...
This version of the test lights a lamp when the ring touches the tortuous wire. The SCR can be the...