Proximity Detectors Circuits

DTMF Proximity Detector:

Dual Comparator: forms temperature-compensated proximity Detector

Dual Comparators Stabilize Proximity Detector: 02/16/98 EDN-Design Ideas

Magnetic Proximity Switch

Optical Proximity Detector: A "reflector" isolator (A) detects the presence of an object by bouncing light off of it. This technique is useful in circuits that detect when an object is close enough to the sensor (B). 

Proximity Alarm #2

Proximity Alarm #3

RS232C Link Monitors Animal Activity: 11/06/97 EDN-Design Ideas