LM741 Voice Filter (CB25936E)

This 300 Hz to 3.4 kHz filter was found in the May 1989 Radio Electronics magazine. The circuit requires a symmetrical power supply.

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One Hour Timer using the 555 (CB1271E)
We found this configuration in documentation from the 1970s, but all components are current. If a...
Negative voltage regulator (CB9154E)
Found in an Electronic Design from the 90s, this circuit makes use of integrated regulators of the time....
Light Activated Alarm (CB26164E)
This circuit was found in the 1991 Electronics Experimenter's Handbook. It activates a relay when...