This circuit without sensors in series triggering an SCR was found in volume 5 of the 1995 Encyclopedia of Electronic Circuits. The circuit can have the number of sensors changed.
The integrated circuit can be replaced by more modern operational amplifiers like the 741. The...
We found this circuit in the August 1970 issue of Radio Elecronics magazine. It uses the CA3018...
The configuration shown in the figure is quite simple and can be used to activate a signaling LED...