1940s commercial receiver (T1618E)

This receiver was found in a Radio Electronics from 1949. It is a superheterodyne of the time using 6 tubes.

Electronic Micro Organ (CB4440E)
This circuit, which uses only common transistors, was obtained from a 1988 publication, but can be...
Multi-Pass Filter with Multiple Feedback MC1776 (CB4499E)
The integrated circuit used in this filter is not very common today, but the configuration can be implemented...
Two-Channel Mixer (CB23869E)
Published in Radio Electronics magazine in March 1963, this circuit uses 4 transistors of the...