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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Model railway alarm (CB22528E)
This circuit detects traffic problems on a miniature railway by triggering an alarm. The circuit was...
Soft Start Regulator (CB15498E)
When establishing the voltage at the input of this regulator, the output voltage rises smoothly until...
JFET Audio Compressor (CB19998E)
This circuit was found in a Motorola documentation from 1975. Modern equivalent transistors such...