This circuit turns off a relay after a time determined by C1. The circuit was found in the December 1974 Radio Electronics magazine. The relay is rated according to the supply voltage.
The circuit shown in the figure below is from the 1993 Linear Technology Applications. The...
We found this wattmeter that operates between 100 kHz and 70 MHz in a 1974 amateur radio...
This circuit is from documentation from the 80's. The double amplifier used is like to the 741 and...