This circuit is from an August 1984 Radio Electronics magazine. It monitors the state of a RAM backup battery. Resistor R1 determines the battery charge.
This circuit is from a 90s Popular Electronics. It appears elsewhere on this site. Q1 can be any...
This circuit works as a booster operating with signals from 1 to 30MHz. The gain is between 1 and...
This timer circuit was found in a 1980s American documentation. Transistors and SCR support modern...