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.
We found this circuit in a 90's Radio Electronics. The low power circuit activates a 12 V relay...
This circuit was obtained from Dutch documentation from 1967. It uses transistors of the time...
This circuit has its battery charged by a solar system. The circuit uses components that admit...