This assembly is from 1957 from a Raytheon manual, but can be modernized using a BC548, 6 V power supply and common 100 mA relays.
We found this circuit in the April 2013 issue of Electronics Now. Any JFET can be used. Note the...
This adapter circuit was found in a 1990 documentation. It is possible to connect a telephone line...
This circuit is based on the integrated DAC0801 and has an accuracy better than 0.39% on the...