This circuit is from a Radio Electronics from October 1963. The transistor is a power transistor of the time, and two transformers are used. The input has 10k impedance and is powered by 12 V.
This conventional window comparator configuration was found in an old documentation. It is valid...
This circuit for analog instruments was found in a Raytheon documentation from the 1960s....
This circuit in a receiver that allows the capture of distant stations with short waves. The...