text: about proximity switch?   proximity switches are used in industry to detect proximity of moving components. i am from aviation industry so i give example of landing gear down & locked condition sensing being done by proximity switches.the main parts of a proximity switch are the switch module & the target which do not come in contact with each other but come in close proximity. when the target comes in close proximity to the switch a signal is generated from the switch module for the appropriate circuit. there are two distinct types of proximity switches; a) magnetic type; here the switch part of the module consists of an internal magnetically operated microswitch & the same is activated when a magnetic target comes in close proximity to it. b) solid state type; the switch module consists of a gauss generating unit. when the non-magnetic target comes in close proximity to it the internal circuit is completed & a signal is generated.