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I've created a monster...
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What's_nitro?
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I've created a monster... - 04.12.2011, 09:48 PM

A sensored monster, that is.





My dogs decided to freak out as soon as I started recording.

It is Castle Creations 3434-240kV running on 13.4V from my PSU. The motor is a bit skippy, and rings constantly, which makes me think I'm a bit off with the angular spacing of the hall sensors. The calculations were correct, I just fudged up the installation a bit. The ones I used are #A3144-UA. They need to be placed very close to the magnets to work properly. Apparently the can of the motor is very good at shielding the magnetic field, so I couldn't just put the sensors on the outside like some have done with the HC motors. Overall if I can get the spacing right I think it will be fine. What a PITA to get the sensors wired and glued into the endbell, though.....

Last edited by What's_nitro?; 04.12.2011 at 10:44 PM.
   
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What's_nitro?
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04.15.2011, 01:40 AM

So I realized my problem... I calculated the proper mechanical spacing at 17.143 degrees (240/14). Apparently, when I assembled the sensors, I used the magnets to line them up...thereby ignoring my calculations and instead unknowingly using 24.712 degrees (360/14) as the spacing. I've re-made the sensor array with the correct ~17 degree spacing. It worked out that the arc length of 17.143 degrees @ 21.05mm radius (where the sensors are mounted) is close enough to 0.25" that it made spacing them evenly pretty easy.

I got my MM Pro from Mike the day before I ordered it. He must be swamped with orders...I usually get it two days before. I'll be finishing the new sensor array after work today and I'll put up some pics and another (hopefully more successful) video.
   
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brainanator
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04.15.2011, 02:38 AM

really cool, and actually looks pretty good I think. Let's see that video! :D


OFNA Jammin CRT.5e, Savage Flux HP, MBX5Te, SCX10, Multirotors, foam planes
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lincpimp
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04.15.2011, 08:29 AM

I opened this up completely expecting to see a pic of the result of your morning coffee in the bowl...
   
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lincpimp
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04.15.2011, 08:34 AM

Did you have to sand the sensors? Also, what is the wiring? Are the red and black pos and neg, split into 3, and the other wires signal, one color for each sensor??

Good stuff, I want to so this to the cc outrunner I have in my summit.
   
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What's_nitro?
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04.15.2011, 07:19 PM

Haha Linc... Off the top of my head the wiring is like this:

Black - (-)
Orange - "C" Sensor out
White - "B" Sensor out
Green - "A" Sensor out
Blue - 10k Resistor connected to (-)
Red - (+)

The 10k resistor bypasses the thermistor that is usually in the motor. I did have to sand the sensors to an angle in the setup you see above to clear the can of the motor. I've solved that problem with the new array by using a piece of body lexan between the sensors and the endbell.
   
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04.15.2011, 10:20 PM

Well, it's good news/bad news time.

Bad news: The new, and supposedly correct, hall spacing did not work any better than the previous setup.

I didn't bother to take a video of it not working, you'll forgive me right?

The good news: I still have a bunch of hall sensors left so I can try some other setups. I was thinking of trying the old standby of 120 degrees, and maybe 30 degrees. Technically, neither one fits in the math, but, it can't hurt to try.

In other news, all four of the motors run great in sensorless mode...
   
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