This circuit generates a siren sound. It was found in the April 1969 Radio Electronics magazine. The output signal is to be applied to an external amplifier.
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...