# How does a 44E21D hall sensor work? And how to wire?

I've got this component and I don't know how it works. I'd like to how how it works and how to wire it because i want to rebuilt the pcb and modify it a littlebit.

All I know is that it's a sensor for a motor to measure it.

It has 3 pins and I assume it has something to do with PNP.

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please add a photo of the component and a photo of the pcb (front and back). Your question as is is quite difficult to answer. – Vladimir Cravero May 24 '14 at 17:47
I will try to make a photo of the component in a few minutes. My camera can't focus on it while I'm in the bus. (Already tried to add a photo when I made this question) – user43384 May 24 '14 at 17:53
where is the motor usually? that totally looks like an hall sensor to me. – Vladimir Cravero May 24 '14 at 18:02
The motor is usually right next to the sensor and has a gear which overlaps the sensor. When I screw the pcb on its place the motor will run for 2 seconds and then stop to perform another action. But when I take the pcb out of its place and start the motor it will keep running endlessly. – user43384 May 24 '14 at 18:05
44E21D is written on the IC. The MCU is a 12C5608AD. I've checked on Wikipedia what a hall sensor is. And it really is a Hall Sensor when I look at Wikipedia. The gear rotating above the sensor has 2 metal buttons on it. Thanks Vladimir! Post it as an answer please. Now how do I wire it? – user43384 May 24 '14 at 18:31

The chip looks like a hall effect sensor.
As the IR remote receivers in that package there is not only the sensor but also the appropriate circuitry to drive and read it. Two pins are probably power ($V_{CC}$ and ground) while the third is the output.
Looking at your PCB traces I'd make this guess:

• pin 1: $V_{CC}$
• pin 2: ground
• pin 3: output

And the guess agrees with Handoko's link. You can confirm this by powering the board and checking the voltage across pin 1 and 2, or following the traces and seeing where they connect to other components (that's what I did).
Pin 2 connects to a huge copper plane, these planes are usually connected to ground to provide shielding and to carry around the reference voltage.
Pin 1 is connected to a trace that wanders a lot, goes to a couple of connectors and to the microcontroller: no way that's the signal output, that must be $V_{CC}$.
Pin 3 finally seems to connect directly (and only) to a microcontroller pin: now that's your output. If you look closely you can even see the resistor shown in Handoko's link.

My pin order: refer to the last photo, pin 1 is at the bottom while pin 3 is the top one. Pin 2 is in the middle of course.

Addendum: to test it you do not need your motor, a hall effect sensor senses magnets: a fridge magnet or something similar is probably quite enough for it to work. You will need a multimeter or something to tell if the output is high or low. Please keep in mind that the sensor output might not be strong enough to directly drive a LED.

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It works! I've tested it with a small magnet I had in my house. Thanks everyone for your support. Pin 1 is connected directly to the 5V since there is a pad from the 5V going down to the bottom of the pcb and connecting the hall sensor. Vladmir's answered all my questions and Handoko send me a nice wiring example so I'll just pin his answer up! Thanks again everyone! – user43384 May 24 '14 at 19:02

Here's a possible wiring of a Hall effect sensor, although it's a different model from the one in the O.P.

(Source)

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Thanks. I'll test it now. But I've got the motor at my work. So I'll be able to test it with my motor on Monday. Thanks everyone for the support. – user43384 May 24 '14 at 18:52
@Handoko Thank you for finding this information. But please avoid posting link-only answers. Links can go bad over time (this is sometimes called "link rot"). In addition to a link, you should add a short summary of that page, and may be post important pictures from it if there are any. This way, even if that page disappears, we have something to go by. I've edited your post to provide an example. – Nick Alexeev May 24 '14 at 20:27
Thanks Nick, I'll keep that in mind ;) – Handoko May 24 '14 at 21:36