This circuit was found in the November 1974 Radio Electronics magazine. The voltage depends on the supply and the timings of R1 and R2 as well as C1 and C2.
This circuit appears with variations in other points of this section. This version is from...
This circuit was obtained from a 1970s RCA. The circuit uses LDRs as sensors. The resistors depend on the...
This circuit can be used with common drills connected to the 110 V network. With change of R1 and...