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.
With this circuit it is possible to obtain an input resistance of 100Gohms for a multimeter, with...
This amplifier, to detect biological signals in implanted transmitters, uses transistors such as...
This application is not modern since few computers have parallel ports. But you can use this...