The CA3020 integrated circuit was one of the first commercial types, sold in the 1960s. The circuit presented is from 1968 using a power stage with RCA transistors of the time.
This circuit was obtained in a 1977 magazine, but it can still be easily assembled, as the...
This intercom for the 27 MHz band was found in a recent English documentation, working with a...
This relay shield circuit for old computers was found in January 1983 Radio Electronics magazine. The...