The purpose of this circuit, which we found in the November 1986 Radio Electronics issue, is to determine the voltage across a zener diode. Several test currents can be selected.
Found in the October 1992 Radio Electronics magazine, this oscillator is controlled by switch S1....
This circuit was obtained in a 1976 amateur radio manual. The circuit can be made with a 2N2222...
The component used in this circuit is not very common today as the circuit is from the 80's. It...