This symmetrical four voltage source was found in a 1968 Motorola documentation. The circuit is of a type that was commonly used in that time amplifiers.
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...