This circuit generates control signals for stepper motors. We found it in a 90s Popular Electronics. The power can be made with a 5 V supply so that it works as a shield.
This bargraph-type circuit employs a not very common integrated circuit today, but can be adapted...
Found in a 90s Popular Electronics, this circuit keeps an LED on when a phone is in use. Can be...
Maxim Integrated's MAX17682 integrated circuit is available at Mouser Electronics, a...