This circuit is from a 1972 Motorola publication. The used transistor can still be found, but it can be used equivalent. The circuit is powered by the amplifier with which it must operate.
The purpose of this circuit is to measure the intensity of audio signals. We found it in the...
The battery charger suggested in the figure has its current limited by resistor R1. This component can...
This differential amplifier, found in a 1964 Electronic Design, has a gain of 30. The setting can be...