Heartbeat Detector (CB25472S)

This heartbeat sensor circuit was found in the July 1992 issue of Radio Electronics magazine. The circuit uses a 741 with a single power supply.

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Auto Alarm (CB4776E)
This interesting automotive alarm was found in a 90's Popular Electronics. The circuit uses...
Logic Controlled Latching Relay (CB25739E)
Using the 4001 integrated circuit, this latching relay can employ any general-purpose transistor. The...
1W Amplifier (CB6293E)
The PA222 integrated circuit used in this project from an American 1967 documentation is not...