Found in documentation from the 1990s, it uses a sound effects integrated circuit, the SN7677 from Texas Instruments. Unusual component these days.
This high power dimmer uses a unijunction transistor to trigger the triac. The triac is choosen...
This frequency corresponds to musical note C3. Frequency accuracy depends on the accuracy of the...
This transformerless power supply uses an SCR as a regulator. It was found in a Popular...