Trade Shows

26.02. - 28.02.2019, Nuremberg



Gear-tooth / Speed Sensors



The need to sense speed and position of ferrous gears occurs in numerous applications. In order to detect the passing gear-teeth with a Hall Effect sensor it is necessary to provide a source of magnetic energy. The simple way to do this is to arrange a permanent magnet so that the axis of magnetization is pointing toward to surface of the gear-teeth. As a tooth moves across the surface of the magnet the flux will become attracted to the lower reluctance path provided by the ferrous steel structure. When this occurs the flux density measured by the Hall element between the face of the sensor and the gear-tooth increases. If the signal level changes beyond the preset magnitude from the positive or negative peak, the output level is changed. This creates a digital zero speed peak detection speed sensor. It is immune to orientation requirements and can follow the gear speed down to the cessation of motion.
It will detect the first edge of the next tooth immediately after power on.
Melexis has chosen to work with digital signal processing schemes and in this way minimize the magnetic circuit manipulation required by the end user.









Speed Gear-tooth, Camshaft Sensing

Open Collector Switch

VDD range from 3.5V to 24V,
Factory programmable parameters,
Hysteresis from 1.8 to 10mT,
Hysteresis 3.8 12mT

3L TO-92

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Differential Speed, Crankshaft Sensing

Open Drain Switch

VDD range from 4V to 24V,
Simultaneous Speed and Position Sensing,
Large Airgap range,
Detection frequency 15Hz to 30Hz

Thin 4L
TO-92 flat

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