This circuit is from a 1967 Triplett manual. The circuit uses components of the time, the common FET and the general-purpose bipolar transistor.
This filter, from an audio publication from 1977, passes the frequency range corresponding to the...
In the figure we have three voltage doubler configurations that can be used in high and low...
This circuit was found in Motorola documentation from 1966. The lamps are according to power and...