Recommended for automotive applications, this circuit was found in an April 1982 Radio Electronics magazine. The transistor supports equivalents. Sensitivity adjustment is made by R1.
This circuit was found in a 90s Popular Electronics. The components are from the era. R3 must be...
This circuit is from the magazine La Radio per Tutti of 1926. The primary and secondary coil have...
The sensor for this circuit, found in a 1992 publication, is a phototransistor. The power is...