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Hall Effect, Anyone?


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Hoping that the Oracle that is Sideways includes electronics experts:

 

I have a project that involves crankshaft sensors, which are, I think, Hall Effect sensors, with three leads each, Black, Brown and Yellow

I need to know which wire does what.

 

So far, with my multimeter, I've found that snatching a heavy screwdriver off the magnet gets, for the wire pairs:

Black-Red - Nothing

Yellow-Red - 0.02V

Black-Yellow  0.2V

But I assume that this is the sensor acting as a reluctor sensor and that the B-Y pair should carry the current that the sensor uses to activate the signal wire.

This is confirmed by the MM in resistance mode, as that pair has 950Ohms, while the other two have no continuity at all.

 

But if I put a small voltage (4V) across the B-Y pair, and test the other two pairs, I get:

Red-Yellow - Nil

Black-Red - tiny transient signal

 

Is the red lead the signal lead?

 

The sensor is brand new.

John

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Alan's responding to your typo.  I think Brown = red in this case?

 

I don't know how to work it out using the method you are trying (or even if it's possible)

 

I suspect (guess) that red will be positive, black negative and yellow signal. As I understand it, if you connect power to the red and black (bearing in mind that alot of even automotive Hall sensors want 5v not 12v) and your multimeter between yellow and negative, you should see voltage when you bring the correct pole of the magnet near the sensor.  Using the "wrong" pole will not work.  Hall sensors (unlike the two wire inductive sensors) don't care about the velocity of the magnet movement, only the proximity.  You can get on/off ones and variable ones which can be used to measure distance and magnetic polarity.

 

Would help to know the origin / p no. of the sensors you have.  What electronics do you have to read them?  Is it intended for Hall sensors?

 

Nick

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Yes, Black, Red, Yellow leads - no brown!    Have to ID them somehow and colour good as any, but I realise that the colour may be random.

 

It's one of these (two in fact): http://www.ebay.co.uk/itm/For-SAAB-900-9-3-9-5-93-95-Crankshaft-Crank-Shaft-Position-Angle-Sensor-FK-/262679012362?hash=item3d28e3a40a:g:g8EAAOSw8w1YBQw5  But that this is advertised for a Saab is coincidental - I just bought a sensor from the cheap end of a list of 11,000 items.  These bear no markings whatsoever, and looking at that enormous list, I can see many others, identical,  advertised for different cars, so I presume this is a generic item, probably made in China.

They are almost identical (but much cheaper) to these Honeywell sensors at CPC: http://cpc.farnell.com/honeywell/1gt101dc/sensor-hall-effect-gear-tooth/dp/SN36528

 

At present, I was trying to ID the lead functions with a digital multimeter.  The project will need an oscilloscope, probably a USB digital one, like a Hantek, but I will need to know which lead goes where! 

 

John

Edited by JohnD
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Thanks, Nick!

 

"The resistance of the sensor coil can be measured across connector pins 1 and 2, and should be within about 10% of the nominal value (At 20C temp). Both pins should test "open" to pin 3."

I think that's what I've found with my multimeter.

Also, and more generic: https://www.linkedin.com/pulse/inductive-hall-effect-rpm-sensors-explained-kiril-mucevski

 

I hoped to see the response, the signal from the sensor as well, as the output from a Hall is said to be as high as 5-12V, and a digital multimeter should register even a transient.

But I was only running the 'power' leads at 4V, when it should be 5V or 12V.

As I got little or nothing as response, it should be safe to go to 12V supply, which will simplify the design.

 

With that much, I think I can build the rest of the project.  Thanks to all.

John

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