This circuit was obtained in an 80s documentation on telephony. The components used are TTL, and the power must be made with 5 V.
In the figure we have a typical polarization circuit for MOSFETs with a high impedance...
Found ina 1970 American documentation this fast-reading circuit uses a photodiode. Transistors...
Found in a 1970's Radio Electronics, this circuit uses a triac to switch loads on the AC network. This...