Found in an 1868 Mullard documentation this circuit has a dynamic range of 10 Hz to 25,000 Hz. Modern equivalent transistors can be used.
The battery charger suggested in the figure has its current limited by resistor R1. This component may...
This circuit was obtained from an English magazine from 1979, but can be easily assembled today...
This circuit is used to test SCRs like the ones of TIC series. The simulation shows the power line...