This circuit is from a March 1978 Radio Electronics magazine article that showed how to build it. The circuit is TTL based and is powered. The components used can still be found.
This circuit for timing small loads was found in a 1964 General Electric documentation....
This circuit, for bands above 15 MHz, was found in an Argentine publication from the 1970s. The L1...
The 2 uF capacitor used in this circuit must be of excellent quality with a minimum of leakage to...