Virtually any FET can be used on this voltmeter found in old documentation. The indicator is a microamper meter 0-100 uA and the accuracy of the circuit depends on the accuracy of the resistors used.
Old phones with dials can be used in a simple home intercom system, as this circuit from Popular...
This circuit was found in the July 1992 issue of Radio Electronics magazine. The circuit has a...
This simple circuit indicates if the polarity of a load is reversed when it is connected to a...