This amplifier for recording heads was found in a Radio Electronics from September 1963. The circuit uses period transistors but can be modified to work with modern transistors.
We found this source with the CI 723, common at the time, in a 1989 paper. Power transistors must be...
This old voice circuit suitable for telephones of the time was found in a Radio Electronics from...
We found this frequency meter circuit in a 1974 documentation. The circuit is powered by 12 V and...