This relay shield circuit for old computers was found in January 1983 Radio Electronics magazine. The relays are sensitive types with currents up to 200 mA.
Originally designed to trigger a printer with a delay, this circuit can be used for other...
This circuit measures the power of a transmitter being sandwiched between the antenna output and the...
This configuration of PWM control with the LM317 was found in a Popular Electronics from the 90s....