The circuit presented was suggested by Texas Instruments in an opto-electronics manual. The transistor can be the BC548 and the supply voltage depends on the application.
This circuit allows you to use a calculator as a timer by directly activating a sum key with...
This “Half adder” circuit uses NAND gates from a 7400. The power supply must be 5 V. ...
ECL logic circuits can operate at very high frequencies. This circuit was obtained from a 1977...