This 1 to 40 MHz amplifier is from a 1969 Motorola documentation. The components are of the time but admit modern equivalents.
For analog lines, this circuit was found in the August 1994 issue of Electronics Now magazine. The...
This version of the test lights a lamp when the ring touches the tortuous wire. The SCR can be the...
This old symmetrical power supply circuit appeared in the December 1973 issue of Radio Electronics...