With a 120 ohms resistor this circuit can also be used as a shield for 3.3 V output voltages. The circuit uses an opto-diac enabling the control of triacs connected to the power grid with total isolation.
This circuit is from 1995 documentation. Integrated circuits are used which can still be found...
We found this 50 kHz 25 MHz crystal tester in a 1978 QST magazine. The FET can be the BF245 and...
This circuit was found in General Electric documentation from the 1980s. The circuit uses couplers...