For a current of 5A and a supply of 6 V this circuit was found in documentation from the 70s. Transistors admit modern equivalents. Q1 is a PUT uncommon today.
Common operational amplifiers like the TL series, CA3140 and others can be used in this circuit...
This high-gain amplifier was found in the March 1994 issue of Electronics Now magazine. The...
We found this timer for times of a few minutes in a 1974 Ferranti transistor manual. The relay is 37...