ElectricGod
10 MW
[moderator edit: This has been split off from an "off topic" discussion drift in the LightningRods thread (pg 179). However, such good info was posted, and I didn't find a more appropriate thread, so...]
****NOTE: Edited and corrected with updated pictures and additional information.
How to test hall sensors...
This is a newer inexpensive component tester I found on ebay. It will test just about any electronic part with two or three legs and identify what it is. It's better than the original parts tester since it can generate a few wave forms and can be re-calibrated for internal component drift.
This is the halls I have on hand right now. I have another 50 41F halls coming soon. As you can see I've got quite a few that I have tried out. Linear halls are commonly used in throttles.
This is a neo magnet out of a hard drive. Notice how it is polarized on the ends. Also notice in the second picture that the magnet is also polarized on opposing sides. It has 4 magnetic poles! This can really confuse things if you think your magnet works a specific way and it doesn't. I've labeled the magnets 4 poles so that I can't get the magnetic orientation wrong. This magnet has a north and south pole on each end of the magnet.
Normal SS41F halls detect as a bi-polar NPN transistor with a diode from collector to emitter when there is no magnet nearby. In this picture I am testing a Chinese 41F that I bought for about 20 cents a piece on ebay. Real name brand 41F halls will respond identically.
This is a normal 41F hall with a north side of a magnet close to the angled side of it. The hall detects identically as if it had no magnet in front of it. Every hall I have ever tested that was good and going to be used in a BLDC motor, looked just like this when a North sided magnet is brought close to it (see the below NOTEs).
This is a normal 41F hall with a South facing magnet next to it. IE: you get back to back diodes. The diode between the hall signal pin and ground act like a current path to ground that pulls the controllers hall signal down to ground.
NOTE1: Halls tend to come in a few different variations. 41F halls always show as a transistor like the above pictures in the presence of a north magnetic pole or no magnet. When the south pole of a magnet is brought close to the angled face of the hall and the part is retested, they are detected as two back to back diodes. If you buy 41F halls or any halls for use in a motor and they do something else, then don't use them. Some halls work the exact opposite. With no magnet nearby, they are two back to back diodes and then when the North side of the magnet is brought near the hall face, the hall is detected as the transistor. I have received quite a few 41F halls that worked backwards like this. Notice that bag above full of backwards 41F halls. Then there is the third iteration I have seen. Some halls use the south face of the magnet instead. It just depends on how that particular hall was designed. For any BLDC motor, you need halls that react like the above pictures show. If you get any other result first confirm your magnet poles are correct and then if the results don't match up, don't use that hall. Halls that don't work correctly will cause aberrant motor behavior. Don't use halls that don't work correctly.
NOTE2: Don't assume that just because you bought 20 halls from a reputable vendor, that they all work the same. The last batch of 41F halls I bought had 7 that operated in reverse and the rest operated correctly. I don't know what happened...maybe some of a different model accidentally got into the wrong production line? Anyway, those 7 halls are not usable for motors. IE: Test the halls before you solder them in place or else your motor will never run correctly.
NOTE3: Motor controllers that can use halls have pull-up resistors on each hall signal. This effectively holds the hall signal at 5 volts until something pulls it to ground. That's where the hall comes into play. When a 41F hall is facing a north magnet, it outputs 5 volts and the motor controller detects nothing. When a hall detects a south magnet pole it goes to ground. Since motor controllers are pulling their hall inputs to 5 volts and typical halls detect north on magnets and output 5 volts, then that means controllers are looking for the hall signal to transition to ground. It's the only thing the controller can detect. That means it is effectively looking for south facing magnets to pass in front of the halls. If you use halls that work opposite of how all controllers are designed, there is a very good chance that the controller will glitch or misread the motor position or it will run the motor roughly.
NOTE 4: If you test with a magnet, you will need to know which side of the magnet is the North vs South side so that you always test consistently the same way. I have a test tool that has two LEDs on it that light up for either North or South depending on what is detected. A compass will also work, but it us subject to all nearby magnetic feilds. If the North end of the compass points at the magnet face, that's the North pole of the magnet. IF the South end of the compass points at the magnet, that's the South pole of the magnet.
I test halls in 3 ways, but first let me repeat myself...
Your halls should look like the below pictures if it's a hall for a BLDC motor. Other halls vary based on how they are designed and what they are used for...See the NOTEs. If I don't get these results, then the hall needs to be replaced and can't be used in a BLDC motor. The result is that you should always get either the transistor or the back to back diodes as a dead minimum. Anything else is a bad hall. All BLDC motors use halls that detect South magnetic poles regardless of the specific hall part number. The important detail is that north facing magnets or no magnet should result in the transistor and a south magnetic pole detects as the back to back diodes. Anything else is wrong.
1. Put the hall in my electronics component tester and see if it comes up as a bipolar transistor with a diode from collector to emitter with no magnet present or a north magnetic pole.
2. Then I bring a south magnet pole close and test the hall again. It should look like this.
3. Then I remove all magnets and test again. It should look like this.
This is the first parts tester I bought. It worked well, but the new one is better.
http://www.ebay.com/itm/Digital-All-in-1-Component-Tester-Transistor-Diode-Capacitor-Inductor-ESR-Meter-/191870868908?hash=item2cac651dac:g:1pAAAOSw8vZXNJCK
Later some Chinese engineer improved it a good bit and made this new one. I have since retired the original tester.
http://www.ebay.com/itm/EZM328-GM328R-transistor-tester-ESR-frequency-meter-square-wave-genera-Z9X3-/182419075876?hash=item2a79063324:g:rowAAOSwo4pYd0bb
Above, I showed tests with halls I had as spares, but It's not awfully hard to test them in the motor with the component tester. This is my hall connector at the motor. I use these IP68 connectors universally for everything I build. Your hall connectors will vary, but the wire colors will correspond to the same things. Red is +5v, black is ground, yellow/blue.green = hall signals. To test halls in motors I made up a short "test" adapter that I can plug into my component tester.
This is the test adapter I made up. I just connect it to the motor hall connector and then use the component tester on those bare wire ends. The red and black wires are +5 volts and ground so you retest with them each time, then the blue, green and yellow wires are the hall signals for each phase. Just try each colored wire one at a time with the power wires. The halls are always in the presence of a magnet inside the motor so you need to know which hall is which and whether it has a north or south pole facing it. You should be able to see the hall transition to transistor or diodes depending on whether it has a north or south facing magnet in front of it. If it transitions correctly, then that hall is probably good. The tester usually displays "unknown device" if the hall is bad or it displays something that isn't one of the two examples shown above. I have yet to see a hall that's good that detects as something other than a transistor or two diodes. If you really want to be dead sure the halls are working, then remove the armature from the motor and then test each hall with a small magnet with known poles.
You can also test the halls with a multi-meter. I'm not fond of this method since it is essentially the LED test. All you know is the hall is on or off, but not if it's internally correct like the parts tester shows. You still need to know which hall you are testing and what magnet face is in front of it. Connect your meter to the hall wire and ground and set it to a low DC voltage range. Power the halls across red and black with 5 volts. Place a north facing magnet in front of the hall under test. It should read pretty close to 5 volts. Now turn the motor a little until a south facing magnet is in front of the hall. The meter should read around 0 volts. Don't assume that just because a hall transitions from 5 volts to 0 volts that it is good. It is possible you have a reverse hall. Halls that work backwards transition too...this is NOT proof of a good hall!!!! They must go to 5 volts in the presence of a NORTH magnet face and to 0 volts in the presence of a SOUTH magnet face for the hall to be good.
****NOTE: Edited and corrected with updated pictures and additional information.
How to test hall sensors...
This is a newer inexpensive component tester I found on ebay. It will test just about any electronic part with two or three legs and identify what it is. It's better than the original parts tester since it can generate a few wave forms and can be re-calibrated for internal component drift.
This is the halls I have on hand right now. I have another 50 41F halls coming soon. As you can see I've got quite a few that I have tried out. Linear halls are commonly used in throttles.
This is a neo magnet out of a hard drive. Notice how it is polarized on the ends. Also notice in the second picture that the magnet is also polarized on opposing sides. It has 4 magnetic poles! This can really confuse things if you think your magnet works a specific way and it doesn't. I've labeled the magnets 4 poles so that I can't get the magnetic orientation wrong. This magnet has a north and south pole on each end of the magnet.
Normal SS41F halls detect as a bi-polar NPN transistor with a diode from collector to emitter when there is no magnet nearby. In this picture I am testing a Chinese 41F that I bought for about 20 cents a piece on ebay. Real name brand 41F halls will respond identically.
This is a normal 41F hall with a north side of a magnet close to the angled side of it. The hall detects identically as if it had no magnet in front of it. Every hall I have ever tested that was good and going to be used in a BLDC motor, looked just like this when a North sided magnet is brought close to it (see the below NOTEs).
This is a normal 41F hall with a South facing magnet next to it. IE: you get back to back diodes. The diode between the hall signal pin and ground act like a current path to ground that pulls the controllers hall signal down to ground.
NOTE1: Halls tend to come in a few different variations. 41F halls always show as a transistor like the above pictures in the presence of a north magnetic pole or no magnet. When the south pole of a magnet is brought close to the angled face of the hall and the part is retested, they are detected as two back to back diodes. If you buy 41F halls or any halls for use in a motor and they do something else, then don't use them. Some halls work the exact opposite. With no magnet nearby, they are two back to back diodes and then when the North side of the magnet is brought near the hall face, the hall is detected as the transistor. I have received quite a few 41F halls that worked backwards like this. Notice that bag above full of backwards 41F halls. Then there is the third iteration I have seen. Some halls use the south face of the magnet instead. It just depends on how that particular hall was designed. For any BLDC motor, you need halls that react like the above pictures show. If you get any other result first confirm your magnet poles are correct and then if the results don't match up, don't use that hall. Halls that don't work correctly will cause aberrant motor behavior. Don't use halls that don't work correctly.
NOTE2: Don't assume that just because you bought 20 halls from a reputable vendor, that they all work the same. The last batch of 41F halls I bought had 7 that operated in reverse and the rest operated correctly. I don't know what happened...maybe some of a different model accidentally got into the wrong production line? Anyway, those 7 halls are not usable for motors. IE: Test the halls before you solder them in place or else your motor will never run correctly.
NOTE3: Motor controllers that can use halls have pull-up resistors on each hall signal. This effectively holds the hall signal at 5 volts until something pulls it to ground. That's where the hall comes into play. When a 41F hall is facing a north magnet, it outputs 5 volts and the motor controller detects nothing. When a hall detects a south magnet pole it goes to ground. Since motor controllers are pulling their hall inputs to 5 volts and typical halls detect north on magnets and output 5 volts, then that means controllers are looking for the hall signal to transition to ground. It's the only thing the controller can detect. That means it is effectively looking for south facing magnets to pass in front of the halls. If you use halls that work opposite of how all controllers are designed, there is a very good chance that the controller will glitch or misread the motor position or it will run the motor roughly.
NOTE 4: If you test with a magnet, you will need to know which side of the magnet is the North vs South side so that you always test consistently the same way. I have a test tool that has two LEDs on it that light up for either North or South depending on what is detected. A compass will also work, but it us subject to all nearby magnetic feilds. If the North end of the compass points at the magnet face, that's the North pole of the magnet. IF the South end of the compass points at the magnet, that's the South pole of the magnet.
I test halls in 3 ways, but first let me repeat myself...
Your halls should look like the below pictures if it's a hall for a BLDC motor. Other halls vary based on how they are designed and what they are used for...See the NOTEs. If I don't get these results, then the hall needs to be replaced and can't be used in a BLDC motor. The result is that you should always get either the transistor or the back to back diodes as a dead minimum. Anything else is a bad hall. All BLDC motors use halls that detect South magnetic poles regardless of the specific hall part number. The important detail is that north facing magnets or no magnet should result in the transistor and a south magnetic pole detects as the back to back diodes. Anything else is wrong.
1. Put the hall in my electronics component tester and see if it comes up as a bipolar transistor with a diode from collector to emitter with no magnet present or a north magnetic pole.
2. Then I bring a south magnet pole close and test the hall again. It should look like this.
3. Then I remove all magnets and test again. It should look like this.
This is the first parts tester I bought. It worked well, but the new one is better.
http://www.ebay.com/itm/Digital-All-in-1-Component-Tester-Transistor-Diode-Capacitor-Inductor-ESR-Meter-/191870868908?hash=item2cac651dac:g:1pAAAOSw8vZXNJCK
Later some Chinese engineer improved it a good bit and made this new one. I have since retired the original tester.
http://www.ebay.com/itm/EZM328-GM328R-transistor-tester-ESR-frequency-meter-square-wave-genera-Z9X3-/182419075876?hash=item2a79063324:g:rowAAOSwo4pYd0bb
Above, I showed tests with halls I had as spares, but It's not awfully hard to test them in the motor with the component tester. This is my hall connector at the motor. I use these IP68 connectors universally for everything I build. Your hall connectors will vary, but the wire colors will correspond to the same things. Red is +5v, black is ground, yellow/blue.green = hall signals. To test halls in motors I made up a short "test" adapter that I can plug into my component tester.
This is the test adapter I made up. I just connect it to the motor hall connector and then use the component tester on those bare wire ends. The red and black wires are +5 volts and ground so you retest with them each time, then the blue, green and yellow wires are the hall signals for each phase. Just try each colored wire one at a time with the power wires. The halls are always in the presence of a magnet inside the motor so you need to know which hall is which and whether it has a north or south pole facing it. You should be able to see the hall transition to transistor or diodes depending on whether it has a north or south facing magnet in front of it. If it transitions correctly, then that hall is probably good. The tester usually displays "unknown device" if the hall is bad or it displays something that isn't one of the two examples shown above. I have yet to see a hall that's good that detects as something other than a transistor or two diodes. If you really want to be dead sure the halls are working, then remove the armature from the motor and then test each hall with a small magnet with known poles.
You can also test the halls with a multi-meter. I'm not fond of this method since it is essentially the LED test. All you know is the hall is on or off, but not if it's internally correct like the parts tester shows. You still need to know which hall you are testing and what magnet face is in front of it. Connect your meter to the hall wire and ground and set it to a low DC voltage range. Power the halls across red and black with 5 volts. Place a north facing magnet in front of the hall under test. It should read pretty close to 5 volts. Now turn the motor a little until a south facing magnet is in front of the hall. The meter should read around 0 volts. Don't assume that just because a hall transitions from 5 volts to 0 volts that it is good. It is possible you have a reverse hall. Halls that work backwards transition too...this is NOT proof of a good hall!!!! They must go to 5 volts in the presence of a NORTH magnet face and to 0 volts in the presence of a SOUTH magnet face for the hall to be good.
i can test all of it with my DMM as well, but i like those small little geeky gadgets. and the display is a real added value.
