This General Electric circuit was found in a 1964 documentation. The circuit triggers a relay when the sensor is activated. Trigger adjustment is done in a trimpot.
This circuit was obtained from an English magazine from 1979, but it can be easily assembled today...
This circuit is from a cookbook to timers. The circuit is triggered by an external signal and,...
This small transistor amplifier was found in an ancient American documentation. Transistors can be replaced...