This wired intercom circuit was found in an English publication from the 80's. The integrated circuit can be replaced by an equivalent, just like the transistor which is a general-purpose type.
This traditional oscillator circuit that can be found elsewhere in this section uses general...
With NAB equalization we found this circuit in an English documentation from 1967. The transistors used...
This circuit was found in Radio Electronics magazine from June 1963. The range is small and the...