This circuit was originally designed with the operational 747 which is rare today. However, the circuit is valid for any operational that must be powered by a symmetrical source.
This circuit uses a crystal phone and can be built with more modern transistors like the BC548. The...
The resistors in this circuit marked with * must be within 1% tolerance. The circuit is from the...
The existence of field effect transistors at the input of the integrated circuit (operational...