This circuit was found in the July 1978 issue of Radio Electronics magazine. The circuit uses a common digital voltmeter as the indicator. The sensors are integrated circuits of the time.
This circuit was found in the February 1981 issue of Radio Electronics magazine. The circuit uses...
Found in American documentation from the 90's, this circuit oscillates up to 150 MHz. The...
This circuit can work with power voltages from 6 to 35 V, being suggested by the Motorola Linear...