With the circuit shown in the figure, it is possible to connect or disconnect a load controlled by the relay by touching the sensors X1 and X2.
Found in Popular Electronics from the 90's, this circuit uses common components and can be easily...
This circuit was found in a 1973 publication. The SCR may be the TIC106 and must use a heat sink,...
This circuit was obtained from my Mechatronics Sourcebook, published in the United States. In it...