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 is from a 1976 Motorola CMOS manual. It can be implemented with modern Darlingtons like...
In the figure we have the way of modulating or controlling the frequency of a relaxation...
The purpose of this circuit is to monitor the operation of an alternator in cars with a 12 V...