This three-transistor circuit was found in Radio Electronics magazine from May 1969. The circuit is for hearing aids and has earphone listening.
Based on the LF256 operational amplifier, this circuit was found in the September 1989 issue of...
This adjustable source from 2 to 15 V uses transistors from the 60's, as indicated in the...
Found in a 90s Popular Electronics, this circuit is intended for amplifying analog video signals....