Found in the February 1983 Radio Electronics magazine, this circuit uses a FET and has good gain at the frequencies determined by the components. The FET is any general-purpose FET.
This circuit generates a PWM control signal using TTL logic. We found this configuration in a 1976...
This circuit, found in EDN documentation from the 90's, implements a clamp without signal...
September 2017 - Arduino Lucky Shield shields containing a 5 V OMRON-g6RL relay, a Everylight...