This circuit is from an old American publication, using transistors of the time and operating with a 48 V power source. The load is 2.2 ohm, and the transistors must be replaced by modern equivalents.
The circuit illustrated in the figure can supply currents of up to 3 A under 12 V voltages with...
This power supply is indicated for the supply of not very powerful car radios of the AM and FM...
The basic idea of this circuit is to convert the indication of a magnetic sensor to an audio tone...