This circuit was found in a 1980s documentation. The diodes may be general purpose diodes such as 1N34 or 1N60 and the indicator may be the lowest current range of a multimeter.
This circuit appeared in the June 1990 issue of Radio Electronics magazine. Integrated circuits must...
Lockout shooting, due to the incidence of light, can be achieved with the circuit in the figure. In...
This circuit can function either as a crystal or galena receiver with a pre-amplifier using a FET...