Suggested by an old RCA manual, this circuit makes use of the period components. Data for the transformer is provided in the original documentation from the 1960s.
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...