This TTL heads or tails circuit was found in the July 1973 Radio Electronics magazine. The LEDs are types of the time. Note the symbolic representation of this component.
Found in a Popular Electronics from the 90's, this circuit uses integrated from that time, today...
This tone generator for CW was found in a publication by Gernsback from 1960. The circuit makes use...
Based on the LF256 operational amplifier, this circuit was found in the September 1989 issue of...