Using the 555 and 4020, this timer was found in the July 1994 Radio Electronics magazine. The relay is voltage-dependent, and the transistor is general purpose.
The scratch is the noise of scratching or scrape that occurs when scratched vinyl records are...
The purpose of this circuit is to eliminate RF picked up by a turntable. The circuit is from a...
The circuit shown uses an operational transconductance amplifier such as the LM3900. Transistors...