Hi,
A have took a PC fan Apart and found a 3 pins hall effect sensor inside it.
I used it to lighten a 12V bulb via a neodymium magnet in 4cm distance.
Now I want to know if there is any electrical way to increase the distance to more than 8cm?
Thanks.
P.s, How those 4 Pins hall effect sensors do work? and why they have 4 pins?
First method would be to place a hunk of ferrous metal in front of the sensor.
That increases it's sensitivity. The increase depends on the metal so you
might try several kinds of metals or simply several different kinds of metal
objects.
One such object that works a little is a metal binder clip. It's not that great
though, but acts as a metal 'core'.
Another object would be a piece of transformer metal like the kind you find in
wall warts (made for 60Hz). You need to get the grain orientation correct
though in relation to the HE device.
Second method is to 'bias' the Hall Effect Sensor with another small magnet
placed close to the HE sensor but not close enough to trigger it. If you get
the pole right, when you bring another magnet with the same pole somewhere
in the vicinity it will trigger the HE device at a distance that would end up
being closer to the HE chip. This is probably the best method because it allows
a lot of change of sensitivity.
The small magnet may be placed off to one side slightly, but some experimentation
could yield the best results. You'll need to get it just right so that it will also
allow the device to turn off too. How well it works will depend partly on the
magnetic hysteresis of the actual part you have.
You can also use this method to desensitize the HE device a little by placing the
smaller magnet with it's opposite pole toward the HE device.