Found in Popular Electronics from the 90s, this circuit consists of a timer that turns off the power of a circuit after a time determined by C1, saving the battery.
Found in a 1968 EEE, this circuit accepts frequencies from 1 to 1000 Hz and control voltages from 0.1 to...
This circuit has appeared several times on this site in different applications. This is from 1997...
This setting appears other times in this section from other sources. This is from an 80's American...