Suggested by a 1990 book for amateurs, this circuit makes use of an integrated component that is not common today. It converts signals from one band to signals in a 10.7 MHz band below.
The figure shows how to couple two TTL circuits using an optical coupler to obtain isolation. The...
We found this circuit in an English publication from 1963. The circuit uses germanium transistors of the...
This two-port configuration of the 4001 was found in the April 1988 issue of Radio Electronics magazine....