This circuit with transistors of the time was found in the November 1972 Radio Electronics magazine. The circuit also generates a sawtooth signal for use on an oscilloscope.
This voltmeter has an input resistance of 200 M ohms (47 M ohms resistors can be used in series to...
This transmitter for the 2-meter range with a power of 1.5 W was found in a magazine 73 for radio...
High-brightness LEDs of various colors and even white can be obtained easily in specialized...