This circuit was found in an 80's EDN. The circuit uses a current common CMOS, the 4093 powering an LED. Trigger adjustment is done in a trimpot.
In the figure we have a simple shield of 1 transistor. The supply voltage depends on the relay. The...
The sensor of this circuit is a common transistor and the trigger point is set on the trimpot or...
June 2017 - These new AVX capacitors are suitable for filter applications, considerably reducing...