Found in a 1980s manufacturer documentation, this circuit can be used as an optical shield. The integrated circuit is from the era and modern equivalents can be tried out.
This circuit multiplies the input voltage by 3 and can work with up to 12 V input. The current is a few...
This circuit was obtained in a Hands-On Electronics from the 90's. The circuit turns on one LED at...
This telegraph monitor was found in an American documentation for radio amateurs from the 1970s. The...