Found in an 80's Hands On Electronics, this circuit turns on a light when it gets dark and goes out when it gets dark. The circuit can be adapted to use high-brightness white LEDs.
This circuit operates with an AM radio tuned to or near 900 kHz if there is a station at this...
This circuit was found in a 1965 General Electric documentation. SCRs and unijunction may be...
Found in a 90s Popular Electronics, this circuit uses a simple 9 V source. The power can be used...