We found this circuit in the November 1974 Radio Electronics magazine. The capacitors determine the output time, and it is normal to obtain 1 second for each uF used.
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...