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 July 1969 Radio Electronics magazine. The circuit uses a coupler made...
The FET of this circuit of a 1971 publication may be the BF245. The circuit serves as a voltage...
This circuit was obtained from an American documentation from 1969. The operational amplifier and...