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#1
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MicroControllers at competitions
I know it is a tad early for me to post about this, but I think that when I go to competition, I should take a Propeller Chip, MCP3204, a 120Amp shunt resistor, and some other various things. The reason why is because last year, we experienced the problem that our shooter motors kept dying and we had no way to measure the motor's current draw (because we didn't want to damage our fluke by a current spike). What do you guys think of this idea to aid in competition debugging?
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#2
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Re: MicroControllers at competitions
Dev,
You are asking for a 0.1 ohm/1500 watt resistor. Do you have those laying around? http://store.mwands.com/diversion-du...12-24-48-volt/ |
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#3
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Re: MicroControllers at competitions
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What's the difference between the device you linked and this one: http://www.amazon.com/Amico-current-.../dp/B008SOXFZC ? |
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#4
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Re: MicroControllers at competitions
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Al's is 125 amps at 12 volts (load resistor) |
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#5
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Re: MicroControllers at competitions
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I can just imagine the little 'uns eagerly tearing open the wrapping paper under the tree, hoping after hope that they were on Santa's nice list... |
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#6
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Re: MicroControllers at competitions
His post was admittedly somewhat ambiguous, but that's not the way I interpreted it.
I think he wants to insert the shunt in series in one of the motor leads and measure the voltage drop across it to get current. Aside from questions of FRC legality, the shunt Ryan linked would would work: it would dissipate roughly 7 watts at 133amps: 0.075V/200A = 375e-6 Ohms. 133amps * 375e-6 ohms = ~7watts. As you have previously pointed out on many occasions Al, instead of a shunt the voltage drop across a length of existing wiring would suffice to get a rough measure of current (for large currents). Last edited by Ether : 12-12-2013 at 16:40. |
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#7
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Re: MicroControllers at competitions
Out of curiosity, what motors were you using?
Are you thinking for in-match debugging, or in the pits? Be aware that in-line current monitoring has been Seems like this would be a good thing to have tested enough in your shop to know that the motors wouldn't die. That way you have time if you need to adjust gear ratios, etc. Speaking of Fluke, what about an AC/DC clamp-on current meter? Last edited by RyanCahoon : 13-12-2013 at 10:35. |
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#8
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Re: MicroControllers at competitions
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#9
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Re: MicroControllers at competitions
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). I've edited my original post. Contrary to the wording of my original post, I was only thinking of the general "custom circuits can't affect power pathways" rule and forgot the exception for low-impedance current monitoring. Presumably (0.075 volts) / (200 amperes) = 0.000375 ohms is low impedance...Quote:
Well it would be good to check the rating on the multimeter first. Not worth blowing unnecessary fuses. Also make sure that the probe leads are large enough to handle the current as well. Last edited by RyanCahoon : 12-12-2013 at 17:21. |
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#10
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Re: MicroControllers at competitions
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What does the current draw tell you? Our team has attended 42 robotics competitions, countless offseason, and have played close to 1000 matches. We have never needed to measure the current draw of a motor at competition, nor have we heard of anybody needing to. |
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#11
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Re: MicroControllers at competitions
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#12
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Re: MicroControllers at competitions
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#13
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Re: MicroControllers at competitions
Dunno, didn't need to. We had Jags on a CAN bus so it was baked in for us. But my gut feeling is no, a clamp on ammeter woulda been fine.
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#14
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Re: MicroControllers at competitions
Beware that most current clamps measure AC only. The DC capable ones tend to be expensive.
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#15
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Re: MicroControllers at competitions
Quote:
http://www.sears.com/craftsman-digit...p-03482369000P |
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