This detector was found in an old Electronic Design using transistors of the time. The circuit can be made with modern equivalent transistors. See the charts with your performance.
This different configuration for a crystal galena radio or modernized since a diode is used, has a...
This circuit is from 1990 documentation. When we press D1 the lamp remains on for a time interval that...
This version of the test lights a lamp when the ring touches the tortuous wire. The SCR can be the...