This circuit operates at a voltage of 1.3 V from a single mercury cell. We found in an old documentation and for the components used the frequency is 500 kHz.
Suggested by an old American documentation the circuit below keeps a battery charged and at the...
This bargraph circuit is from an ancient American documentation. It indicates the charge state of...
This 1967 Electronics World circuit is suitable for frequencies up to 1 MHz. The setting applies...