Passive proximity sensors

This kind of sensor does not need a power supply, and controls the closure state of the sensor by magnetic induction. When magnetic or iron flip-flop approaches the magnetic field of the sensor, it will control the closure with the internal magnetic force of the sensor. Characteristics: no need for power supply, non- contact, maintenance-free, and pro-environment.

Eddy current proximity sensors

This type of sensor is sometimes called as inductive proximity sensor. It utilizes a conducting object which produces eddy currents inside the object when approaching the proximity sensor which produces electromagnetic field. The eddy currents react on the proximity sensor, changing the internal circuit parameters of the sensor, thus identifying whether a conductive object is moving closer or not and then controlling the on-off of the sensor. The object which can be tested by this proximity sensor must be an electric conductor.

1. Principle: an oscillator consisting of an inductance coil, a capacitors and a transistor produces an alternating magnetic field. When a metal object approaches this magnetic field, eddy currents will be generated inside the metal object, causing the oscillation to cease. This change is converted into the transistor sensor signal after the post-pole amplification processing.

2.Characteristics: A. good anti-jamming performance, high switching frequency, more than 200HZ. B, only metal-inductive.

3. It is applied to the testing of the position and pick-up of the counting signal on all kinds of mechanical equipment.