True RMS Voltmeter (CB25353E)

This circuit is from a Radio Electronics magazine from August 1990. The indicator module is of a common type at the time.

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Liquid Flow Meter (CB6340E)
This circuit was found in an old Linear Technology documentation. The working principle can be...
Scratch and Rumble Filter (CB12432E)
Scratch is the scratching noise that occurs on old, scratched discs and the rumble is the...
Commercial Portable MW Radio AT235 (CB18430E)
This 6-transistor receiver was manufactured in Japan in the 60s. The circuit is superheterodyne and has a 6V...