This amplifier for recording heads was found in a Radio Electronics from September 1963. The circuit uses period transistors but can be modified to work with modern transistors.
This sensitive photo-diode circuit with output compatible with TTL logic was found in a 1972 RCA...
This circuit can send signals in both the VHF and FMN bands with a range of a few tens of meters. The...
This circuit was found in a Popular Electronics from the 80s. It is possible to control a relay...