This circuit activates a relay after a time given by C1 and R1. The circuit is from a Radio Electronics from December 1974. The relay voltage is the same as that used in the power supply.
This circuit was found in a 1977 Radio Handbook. The ports used are CMOS like 4001 and the...
I found this Vox circuit or acoustic receiver as it was originally called, in a 1973 publication. The...
Found in RCA documentation from the 90s, this bass and treble control uses an operational...