This circuit is from an ancient American documentation. The integrated circuit is 741 and the power supply must be symmetrical. The passing band is centered at 1 kHz.
This circuit is more sensitive than the previous one, triggering when a laser beam that hits the...
This circuit was obtained in a 1967 Electronics World. The components are still common today, the...
The simple touch of the fingers on a sensor causes this circuit to drive a motor that goes into...