The circuit is from 1968, but we can use a modern one like the 741. The symmetrical power supply voltage (two batteries or source) can be from 9 to 12 V.
This source circuit was obtained in a 1976 publication for radio amateurs. The transistors can be...
We found this circuit in Radio Electronics Special Projects from 1992. The circuit turns on the...
This circuit takes advantage of the noise generated at the junction of a zener diode of any type....