Found in an Electronic Design of 1964 this circuit has a control for the frequency and another for the active cycle the signal. The bipolar transistor can be a general-purpose type.
This circuit, which in our times would be called a shield, can also be used with other loads. The...
This circuit is from an old American documentation from the 70s. Transistor 2N3904 can be replaced by...
This application of the 555 was found in the November 1992 Radio Electronics magazine. The...