speed sensing

[Dexter12353]

I am working on making a speed sensor work for a project I have been working...the sensor the speed gauge came with was extremely weak.  It literally had to be less than 1mm away from the magnet to pick it up.  Do you guys think I could purchase some stronger sensor and get it setup so it can detect a magnet from roughly 5mm away?

I looked into hall effect sensors and got lost when it said required gauss, I don't know exactly how strong the magnets are, but a screw driver will stick to the ones already installed.  I also have some rare earth magnets that I can stick on top to make them stronger.

Any help is extremely appreciated!

[Dago]

The sensor is most likely a reed switch. To replace it with a Hall sensor you'd need a comparator in between. Just stick a stronger magnet and it will probably work well enough.

[Psi]

+1 for bigger magnet

You can get free rare earth magnets from around the lens in old CD/DVD drives and larger magnets from hard disk drives at the pivot point of the head arm.

[mikerj]

The sensor is most likely a reed switch. To replace it with a Hall sensor you'd need a comparator in between. Just stick a stronger magnet and it will probably work well enough.

The other thing to note with reed switches is that they are very sensitive to orientation with respect to the magnetic field.  They tend to be least sensitive when they are parallel and centred to the face of the magnet, applying the field to one end of the reed switch greatly boosts the range over which they can activate.

[Dexter12353]

I'm sorry for not mentioning the sensor it came with was 3 writes...1 12 wire and a ground