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 1967 Philips circuit recognizes a light signal (visible or infrared) modulated by tone. The...
This circuit turns on an old cassette recorder when the telephone rings, thus enabling the...
This is the receiver for the previous circuit transmitter. Similarly, no information about the...