Found in documentation from the 1980s, this circuit uses an operational amplifier from that time. Transistors are also from the era, and general-purpose equivalents can now be used.
This circuit causes an instrument needle to oscillate to signal an event. The circuit is powered by...
A touch in this circuit turns-on the lamp or the relay. Power supply is according the lamp or...
This biestable circuit was found in a Popular Electronics from the 90s. The circuit has an unusual...