This circuit, from a 303 Circuits from the 90s, uses a telephone pickup coil as a sensor to capture power grid noise, thus making it possible to locate electrical wiring.
This circuit has a load connected to the ground providing 5 W of power at 16 ohms. The circuit is from...
We found this circuit in the February 1970 Radio Electronics magazine. It can be used in an analog...
This 1 kHz oscillator has enough power to directly drive a small speaker. The supply voltage is 5...