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Hall effect sensor bypassing?

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Hi guys,
i'm trying to reverse engineer and alter (not for any profit or gain of course) a part of my car.

This particular PCB contains a hall effect sensor which are new to me. From what I understand is the sensor allows a greater flow of electrons through it as a magnetic field passes it.

the questions I have, if I may are:
do the sensors ever become 100% efficient and allow all the current flow through or is there always a loss?
is it possible to bypass the sensor with a switch?

From what I can fathom out is that the sensor output is monitored to a certain degree and when the current rises to, or above, a certain level, the circuit will switch. From that I assume that connecting the input voltage to the output pin via a switch would allow a fake signal to be generated to the switching part of the circuit.

It would great if anyone could confirm, deny or help with this.

The hall effect sensors are, I believe, unipolar, 4 pin (dual earth) IC's. The number on the top is 41E if that is any help.

Thanks in advance to anyone who can help.

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The hall sensor lets flow current distributed in a large area. The material has a definated resistance. The sensor is wasting power an so where is always a voltage.

Its easy to measure the resistants of the hallsensor by checking the power loss, if you test it with a magnet.

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I know two Kinds of Hall Effect sensors...

One type are a Switch like UGN3113 that if they sens a specific value of Flux they switch on a Open-Collector Output.

The other type are Linear like UGN3503 that their output is a linear voltage depending on Sensed Flux.

Maybe this can help you to solve your problem

HTH - Shahriar

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What part of this is controlled by the Hall effect sensor? Is it the automatic clutching part? It would be good if you could get a schematic. If not, you can put a voltmeter across the input and output to see what voltage drop you have between engaged and not engaged. This will tell you if it is being used as a basic on-off switch. It will also help you determine the loss for both positions.


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It is literally used to change gears, the underside of the gear lever passes over the hall sensors and depending on which one it passes, it will change up or down.

I will try your suggestion of measuring the output with and without, I can only assume that introducing the correct voltage to the output will fool the system into switching.

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