Hi, I was wondering if the NKC motor shield (Arduino Shield List: NKC Electronics Motor Control Shield) would work with these motors aero-nuts.com . Also, does this shield have protection from the high voltages generated after the power to the motors is cut. Thanks for the help.
Highly unlikely - I highly doubt the motors are a low enough current draw to be controlled by that motor shield.
Thanks for the reply. Could you recommend a different shield?
Also are there any problems with powering the motors from a 2 cell LiPo?
edit:Is it possible to check the current draw of the motors without a functioning multimeter? (I have access to a semibroken analog one that doesn't really work :D).
edit again: Can't I just underpower the motor?
edit again again: Would I be able to piggyback another SN754410 ontop?
Brushless RC motors need lots of amps, their windings are less than 1/10 of an ohm, they need specialized drivers (called ESCs in the RC world). These use ultra-low Ron MOSFETs to drive heavy currents (typically 30A+) to the windings and auto-sense phase from the back EMF of the unpowered winding. Remember typical RC motors weigh ounzes and are rated 100W to 2000W... They are very different!
Thanks for the reply, but the motors I have are just plain brushed motors. So no brushless escs are needed. (I am aware that r/c hobby grade brushed escs exist, however I am aiming for as cheap as possible and I have not had any luck finding a bidirectional esc that is cheap as well).
Ah, old technology! What's the resistance across the terminals? From that you can work out the stall current it will pull. You'll have to power it up to measure the no-load current.
If you come close to stalling, it looks like your going to need a ~20A motor driver - these can get quite expensive. They also will NOT be available as shields - you will need to hook up some other circuitry.
At the 'higher cost' level, you might be able to use a Sabertooth 25A or RoboClaw 2x25A controller (~$125). If you don't need reverse, an RC plane ESC may be substantially cheaper ($20/motor), or possibly an RC car or RC boat ESC ($30/motor).
This ESC looks like a good deal, but I have no personal experience with it: http://store.polkshobby.com/scripts/cgiip.exe/WService=takestock/itemdet.html?itemnum=PLK00100&conum=002
Any reason why you want to use these motors? There are many, many better ones.
He can't use standard RC ESCs as they aren't brushless motors.
There are RC ESCs for brushed motors. Old school, but they exist.
http://www.castlecreations.com/products/pixie-7p.html
Those would run one of those motors just fine.
Is stall current the current it draws when it is stopped from moving? Could I just add a resettable fuse so it never draws over a set amount of amps? (This is what was done with a r/c lama to stop it from frying the electronics when the blades where hindered from moving.) I want to use these as they're the only pair of motors that I have on hand.
mcookieman:
Would that require a multimeter? / Is the stall current in aero-nuts.com the one required?
If you don't have a multimeter, I suggest you get one; without having this very basic (and very inexpensive) piece of test equipment, you are more likely to spend money burning things out rather than making progress in your project(s).
Note, though, that most inexpensive multimeters max out for current measurement at around 20 amps; some can go higher, but costs go up. However, if you understand Ohm's Law, you can instead build/buy a current shunt, and use it to figure out the total current draw.
Buy a meter - you won't regret it (you don't need a fancy one, either - an el-cheapo Harbor Freight Cen-Tech for $2.99 will work just fine).
As there are no electronics shops near me (I blame DSE for dropping hobbyist electronics), I have not had a chance to buy one. I plan on getting one when/if i get a motor shield.
mcookieman:
As there are no electronics shops near me (I blame DSE for dropping hobbyist electronics), I have not had a chance to buy one. I plan on getting one when/if i get a motor shield.
Well - where do you live? Any hardware stores? Air conditioning repair outlets? TV/Radio service centers, etc? Auto repair parts? What about Ebay? Surely there's got to be a place near where you can buy a multimeter (it doesn't have to be an electronics shop)...
mcookieman:
Is stall current the current it draws when it is stopped from moving? Could I just add a resettable fuse so it never draws over a set amount of amps? (This is what was done with a r/c lama to stop it from frying the electronics when the blades where hindered from moving.) I want to use these as they're the only pair of motors that I have on hand.
You could add the fuse, yes, but nevertheless, the ESC will cost you much more than better motors will. Since the motor has no gearing, it will run really fast, but won't be able to do much work before stalling - you'd be better off getting a gearmotor of some kind, or trying to pull the gears off of your helicopter.
vinceherman:
[...]
http://www.castlecreations.com/products/pixie-7p.htmlThose would run one of those motors just fine.
That one maxes out at 7A: the one I recommended (http://store.polkshobby.com/scripts/cgiip.exe/WService=takestock/itemdet.html?itemnum=PLK00100&conum=002) supposedly maxes at 100A, and looking at the wiring, its clearly a brushed controller (brushless have three motor leads, not two).
What motors + driver would you recommend for a small car?
Depends on how small =).
For small robots, this combination works well:
Motors: Two Solarbotics GM8 or GM9 motors: Pololu - Solarbotics GM8 143:1 Gear Motor Offset Output
Driver: L293D quad half h-bridge OR TI SN745510 quad half h-bridge (they're pin compatible, but the TI chip handles greater currents and is cheaper. Any tutorial for the L293D will work for the TI, but beware: both require external flyback diodes if you hook them up correctly - tutorials which claim the L293D doesn't need them aren't valid. )
Would http://cgi.ebay.com/Low-Cost-Gear-Motor-2-Pieces-DC-robot-chassis-/280581321548?pt=LH_DefaultDomain_0&hash=item4153f3334c#shId be suitable? as it is half the price of the solarbotics gearmotors and I'd like to keep this cheap being a jobless teen.
edit: Also if I don't purchase a motor shield how would I go about implementing flyback protection? (I understand that if It only travels in a single direction you only need one diode across the motor contacts, however with bidirectional control, this wont work?).
Those would be fine (they're like a dollar or so cheaper, total - you're not saving much, especially since you'll need to pay shipping on the motor driver too. Sparkfun may be better for you - it's got more basic electronics).
The adafruit motor driver shield is just a few L293D's with associated LEDs and flyback diodes - it's not like you can't make your own, for a much cheaper cost.
Schematic for TI SN754410/L293 with flyback diodes:
Thanks for the help, I actually save around 5~6 dollars because of the shipping if i buy the solarbotics ones.
edit: is there a higher resolution copy of that diagram?
edit again: over here for anyone eles who might need it Redirect Notice
edit again again: I'm assuming if i get 2x 1A diodes and wire them in parralell they will equal to a 2A diode?
edit again again again: Can I use BC 548 transistors instead of BC108Bs?