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Topic: Motors issue? (Read 779 times) previous topic - next topic

sec9major

Hi I am using the Uno with the DFRuino L298P motor shield. I have two motors connected to it and when everything is powered up the motors only make a buzzing beep noise, with more current the noise just gets louder.
the motors are only small ones a little bigger then this:
http://www.robotshop.com/ca/tamiya-3-speed-crank-axle-gear-box.html

Any idea's why?
Thank you in advance

MarkT

And how are the motors powered?  And what maximum current do they take?
[ I won't respond to messages, use the forum please ]

sec9major

I am powering them trough the external power supply, first I tried a 9V then I upped it to two 9V's wired together. I could be wrong but I think the motors are 5V.

Thank you for your reply

Pauly

• Gear Ratios: 16:1, 58:1 or 203:1
• Motor: FA-130
• Motor RPM: 12300 (9710 Maximum Efficiency)
• Motor Voltage: 1.5-3V (1.5V Recommended) (4.5 V Max)
• Motor Current: 2.1A
• Motor Stall torque: 36 g-cm

My guess is you are supplying the wrong power.
The specs for this one say supply 1.5 V and 2.1 amps.

What are the specs for your motor?

sec9major

I am not sure what the specs are they are in an rc tank chassis that I has hoping to use that I picked up at a yard sale a few years back.
it was one of those folding track tanks maybe someone knows which one I am talking about? unable to find pictures on google of it. it has grey wheels, black rubber treads, and measures in around: folded 10 inches long X 9 inches wide, unfolded 20 inches long, and its a little over 3 inches high.

but I removed the folding parts to cut down on weight.
the insides of it are missing, but the battery pack meant for it is suppose to be a 9.6V if that helps at all.

cr0sh

Have you measured the current draw of the motor(s) at 9.6 volts (which is likely to be their rated voltage - probably 9-12 volts DC) using your multimeter?

The best way to do this is to remove the motor from the gearbox, hook your multimeter in series with the motor, set the meter to "current measurement" (and make sure the leads are in the "20A" or whatever current measurement jacks), and apply power (briefly - less than 1 second) while keeping the shaft and body of the motor immobile (ie, stall conditions) - you may need to make a special jig to do this. This will give you "worst case" current measurement values, which is what you want to know.

You'll want whatever h-bridge you use to have a maximum current capability of about 15-20 percent over that amount. The L298 is rated at 2A per bridge (or 4A in "bridged" mode - if your shield supports this - although this mode only allows one motor to be controlled, instead of two).
I will not respond to Arduino help PM's from random forum users; if you have such a question, start a new topic thread.

sec9major

lol it would be nice if I had a multimeter. thanks for the suggestion though

I have 2 of the single tamiya gearboxes and they make the same noise but not when directly powered, but they do turn when connected to the motor shield.

would the noise be caused by the shield, motor frequency being to low, or something to do with the code? 

cr0sh


lol it would be nice if I had a multimeter. thanks for the suggestion though


Ok - stop right there; it is imperative that you obtain a meter if you wish to continue with electronics as a hobby. Trying to work with electronics without a meter would be like trying to build a house without tools - while being blind. Could it be done? Maybe. Would I trust the resulting circuit (beyond maybe a kit - and even there, well...)? No.

A multimeter isn't expensive - and an el-cheapo weekend-special from your local (?) chinese cheap tool supplier (here in the States we have places like Harbor Freight and Northern Tools; I'm sure similar places exist where you are at); for instance, here's one from Harbor Freight (a Cen-Tech):

http://www.harborfreight.com/7-function-digital-multimeter-90899.html

That's $3.00 USD, normal price; generally with a coupon I can pick up a few of these on a weekend for $1.99 each; I pay more for a hamburger at my local Jack in the Box. Such a meter isn't the best, but it's a sight better than no meter at all - and honestly, for most hobbyist purposes, these cheapo throw-away meters work great. I always try to pick up one or two when I go to Harbor Freight, so I can add a few to circuits if needed, and if I blow it up or otherwise break it, I'm not out much. Well worth it, IMHO.

So find such a thing local to you - I am certain you can; you'll be much better off in your hobby if you do.
I will not respond to Arduino help PM's from random forum users; if you have such a question, start a new topic thread.

sec9major

Thank you for your reply.
It's not that I haven't had or used one before, its that my last cheap meter fried I do know they help though.
I do need to get some more.

if I added a resister to each motor would it eliminate the buzzing noise?

MarkT

The idea of a motor is to turn electrical power into motion - adding a resistor you will turn some of the power into heat so there's less for the motor - not going to help.   If the motor is too big for the supply this is a problem that needs addressing, its fundamental.
[ I won't respond to messages, use the forum please ]

war_spigot

Maybe the ESR of your power supply(bench? 9v batteries? a whole bunch of AA's?) is too high and the motors aren't getting enough current.

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