Found in an Electronics Now from the 90s, this circuit appears elsewhere in this section and website. The diodes are for general use and the basic frequency is given by C.
This timer, using the ZN1034E, is from a May 1987 Radio Electronics magazine. The circuit can...
This circuit was obtained from a Radio Electronics from October 1963. The 4 transistors must be...
This circuit monitors the current in the loads. The NPN and PNP transistors admit the BC547 and...