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 amplifier circuit with gain between 0 and 96 was found in the December 1983 issue of Radio...
This dimmer for incandescent lamps is one of the many found in this section. This was obtained...
This is the receiver for the previous circuit we found in the December 1992 Radio Electronics...