HALL sensor

Hall effect gear tooth sensor
manufacturer: Honeywell datasheet
This is the most popular easy to mount HALL sensor among engine builders
(Wholesale Q>=50 and checkout with IBAN: 26.5 EUR, which is also the minimum price, regardless of discount level).

Gear tooth sensor based on a Hall effect switch and a magnet sensing movement of ferrous metal targets. The sensor has good properties both at high (near 100 kHz) and low speeds. It is protected against reversed polarity and handles transients of up to +60/−40 V. Digital open collector output.

• Supply voltage: +4.5 to +24 V
• Supply current: 10 mA typ
• Output current (ISINK): 40 mA
• Rise/fall time: 15/1.0 usec max
• Temp. range: −40 to +150 °C

Recommended wheel dimensions:

• Tooth height: min 5 mm
• Tooth width: min 2.54 mm
• Tooth spacing: min 10 mm
• Tooth wheel thickness: 6.3 .. 8 mm

We've seen applications where the heads of M6 or bigger bolts were sensed. Often arranged as

• 1 pulse per event (eg. on a 4cyl: 2 teeth on the crankshaft, 180 crankdegrees apart), falling edge at 58 .. 80 degrees BTDC
• 4-1,6-1, 8-1, 12-1, 12-2 or 24-1 tooth pattern might be most practical. (60-2 works, but not recommended with home-made wheels)

When an installer concludes that it does not work, it is most often just a misunderstanding: this sensor only pulls the output (middle pin) to ground when ferrous material is sensed. So the output must be pulled up externally (usually the ECM pulls up the trigger input). When verifying, measure DC voltage with DVM from +5V or +12V as a base (instead of ground).

• red +supply (usually +5V or +12V). (Recommended: pin3)
• middle: output (the ECM pulls this up with a pullup, usually 2k7 resistor toward +5V). (Recommended: pin2)
• remaining: ground (Recommended: pin1)