Operated directly from the power grid, this detector was found in an 80's RCA documentation. The sensor is an ionization chamber. The SCR triggers a warning siren.
This circuit is from an old documentation of Radio Shack from the 70s. The transistor should...
When the power is cut off, this circuit keeps the flashlight on for a while, allowing it to be...
This circuit was obtained in an old Popular Electronics. It makes use of quite common components....