Rumble filter (CB6541E)

This turntable filter was found on an 80's Elektor. The circuit makes use of operational features that are easily obtainable today.

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Sophisticated Temperature Alarm (CB24164E)
This two-transistor circuit was found in the September 1971 issue of Radio Electronics magazine. The...
1MHz XTAL 7404 Oscillator (CB11869E)
This circuit has its frequency controlled by a 1MHz crystal. The circuit must be powered by a...
Radio as Megaphone (CB17368E)
A portable radio with greater power, such as those using medium or large batteries, can be used as a...