This circuit was obtained in Motorola documentation from 1969. The transistors are from the time with some modern equivalents.
This two-channel wired intercom was found in the April 1990 issue of Radio Electronics magazine....
This relay circuit with a dual channel MOSFET (not very common today) was found in an old American...
This linear LED scale circuit was found in the February 1992 issue of Radio Electronics magazine. Note...