This photoelectric sensor that triggers a relay was found in an English book from 1989. The transistor is a general-purpose type, and the integrated circuit consists of an operational amplifier.
This circuit produces a sine 1 kHz signal. The frequency is given by C1, C2 and C3. This is a...
This receiver can tune in the 3 to 12 MHz band with good sensitivity and selectivity, using a good...
This circuit was found in an old Popular Electronics. With it we can check the operation of a...