This circuit from an old MIT documentation excites an oscillograph element, an old waveform viewer.
This circuit, from the ON Semiconductor Thyristor Manual, controls both the speed and direction of...
A small loudspeaker (2.5 or 5 cm) can be used as a low impedance microphone. A preamplifier and...
If you have an old cassette player or bought one from a junk shop, you can set up a small table...