When are sensors needed?
 
Hall sensors, reed sensors or inductive sensors are used in electronic tachometers to detect speed

 

What are the main differences between the individual sensors?

  • Hall sensor: 
    • works with 12V DC
    • 3 cables (+12V, ground and signal)
    • switching distance: 1.5-2mm (with magnets 8-10mm)
    • signal transmitter: all ferromagnetic metals (screw heads, brake disc bars, gears) - Metal must be attracted by the Magnets. NO STAINLESS STEEL! NO ALLOY!
    • advantages: insensitive to vibrations, no magnets necessary, very flexible mounting, switching distance can be increased with magnets
    • disadvantages: Size
    • peculiarities:
      • original Hall gear sensors (n-shifting) with 3 connecting cables can be used in principle. For Harley Davidson® models from approx. 1996 and Buell® from approx. 1999 there is already a Hall sensor available, which is suitable for our speedometers, if it works with 12V. The sensor sits at the gear and recognizes the teeth of a gearwheel of the main shaft. Only Premium-Line instruments work with 5V sensors!
      • bars, screw heads, teeth, etc. must be evenly distributed over the circumference! The bars and gaps of the brake disc must always have the same width!
      • screw heads must be raised!
      • attention with Allen screws: Here also the "hexagon socket holes" are recognized. We therefore recommend replacing the screws with hexagon head screws.
      • sensor cables should always have a distance of at least 20cm to the ignition coil or be shielded to avoid interference signals!
  • Reed sensor:
    • no voltage necessary
    • 2 cables (interchangeable)
    • switching distance: 1-5mm to magnet
    • signal transmitter: Magnets (at least one, better 3 and more) IMPORTANT: The calculated number of pulses (see instructions of the speedometer) must be higher than 1000!
    • advantages: very small size, large switching distance
    • disadvantages: very susceptible to vibrations (especially with audible brake quits, false signals may occur), magnets are necessary (magnets can demagnetize when subjected to strong heat on the brake disk), magnets can be lost easily
    • peculiarities:
      • rectangular reed sensors must have a narrow side facing the axis of rotation!
      • the magnets must pass the sensor flush at the top or flush at the bottom.
      • magnets must be distributed evenly around the circumference.
      • mount the magnets on a flat, grease-free and rotating surface on the wheel. Points close to the axis of rotation are preferred due to centrifugal forces.
      • do not glue in magnets lower than 1/3 of the magnet height.
      • install magnets in such a way that they are not exposed to more than 80°C - otherwise they will be demagnetized
      • use a suitable adhesive and pull a silicone joint around the magnets for safety reasons.
      • sensor cables should always have a distance of at least 20cm to the ignition coil or should be shielded to avoid interference signals!
  • Inductive sensor:
    • works with 10-30V DC
    • 3 cables (+voltage, ground and signal)
    • switching distance 1.5-2mm
    • signal transmitter: all metals (iron, stainless steel, aluminium, copper, brass, …
    • advantages: insensitive to vibrations, non-ferrous metals are detected, extremely flexible in use,  integrated LED as adjustment aid for the sensor distance
    • peculiarities:
      • bars, screw heads, teeth etc. must be evenly distributed around the circumference! The bars and gaps of the brake disc must always have the same width!
        Pulse generators must be raised!
      • attention with Allen screws: The "hexagon socket holes" are also detected here. Hexagon socket screws must be replaced with hexagon screws or the sensor must be aligned so that only the edge is detected.
      • sensor cables should always have a distance of at least 20cm to the ignition coil or should be shielded to avoid interference Signals!