# Space-efficient control of multiple 12V 3.5A DC motors

#### Kaelin

Dec 13, 2017
5
I'm currently working on a project for which I'm looking to control six brushed 12V DC motors which each have a peak current draw of 3.5A. For a previous similar project, I used these motor controllers (https://www.robotshop.com/en/cytron-10a-5-25v-dual-channel-dc-motor-driver.html) which did their job very nicely. Unfortunately, the space I have to work with right now is quite constrained, so those controllers are pushing the limit of what I can fit in the environment; I'm looking for a smaller alternative which preferably doesn't cost too much more. I think I understand the concepts behind DC motor controllers pretty well, but my background is in CS and software development so I don't have the experience to be confident in this area nor have I worked with electronics past wiring up pre-built components and basic ICs on breadboards.

I've been doing some research and am having a hard time finding reasonable parts which satisfy my requirements. 1A and 2A motor controllers are available in abundance for cheap, but once you get above that it seems like the next major grouping is for much higher ratings and carry a proportionally higher price tag. I see a few options:
• Buy a high-quality pre-made component and eat the cost. This product (https://www.pololu.com/product/2991), for example, seems like a great fit, but it's quite expensive given that I would need six of them. Obviously, the 17A rating is superfluous for my needs.
• Buy a cheap pre-made component and risk the details. I've found components on Amazon (https://www.amazon.com/dp/B01M2WUXM1) which are typical sketchy off-brand Chinese boards and don't provide me much confidence; better price, but lacking on specs.
• Buy a raw motor driver or H-bridge and roll my own surrounding circuitry. I've found a variety of components that seem to suit my needs (some more "raw" than others), but without any experience with PCB manufacturing I don't know what I would be getting myself into. The packaging of these components certainly wouldn't be friendly spacing for, say, a breadboard, and I'm at a loss for what I would do as an alternative. The components generally have reference implementation diagrams which indicate what external components are required, which is good. I'm realizing that I can't explain what it is that makes the other motor drivers so large, which is likely a sign I don't know nearly enough about what I'm doing.
Am I missing options? What avenue of approach seems like it would be most appropriate for me?

Thanks!

#### Bluejets

Oct 5, 2014
6,067
Perhaps the rc range of brushed speed controllers?
May need a different control signal from what you are using (these are ppm)

Example here is a fairly wide voltage supply, forward and reverse with around 10A max.
Have no idea of the quality($5 ...) definitely smaller ........ but there are others. https://www.ebay.com.au/itm/10A-Brushed-ESC-Two-Way-Motor-Speed-Controller-With-Brake-For-1-16-1-18-1-24-RC/301964699081?_trkparms=aid=555017&algo=PL.CASSINI&ao=1&asc=20160706105120&meid=3a7b53e7fff847848704698cf7589225&pid=100508&rk=1&rkt=1&&_trksid=p2045573.c100508.m3226 cheers Jorgo Edit:...sorry...didn't notice these are 7 cell nicad so under your 12v requirement. However there are others as I said. #### Kaelin Dec 13, 2017 5 Perhaps the rc range of brushed speed controllers? May need a different control signal from what you are using (these are ppm) Example here is a fairly wide voltage supply, forward and reverse with around 10A max. Have no idea of the quality($5 ...) definitely smaller ........ but there are others.

https://www.ebay.com.au/itm/10A-Brushed-ESC-Two-Way-Motor-Speed-Controller-With-Brake-For-1-16-1-18-1-24-RC/301964699081?_trkparms=aid=555017&algo=PL.CASSINI&ao=1&asc=20160706105120&meid=3a7b53e7fff847848704698cf7589225&pid=100508&rk=1&rkt=1&&_trksid=p2045573.c100508.m3226

cheers Jorgo

Edit:...sorry...didn't notice these are 7 cell nicad so under your 12v requirement.
However there are others as I said.

Thanks for the tip! I did some research on RC-focused options and am hitting a few issues:

Is there something I'm doing wrong in my search? Do you have any suggestions?

Thanks!

#### Bluejets

Oct 5, 2014
6,067
Don't think so. Trend these days is more biased towards the use of brushless in the r/c environment at least. These use supplies of varying voltages but common to see anything from the7.4v to 22.2v (lipo batteries). Don' t suppose you'd consider a change in motors? There can be advantages such as size but may have to consider cooling.

#### Bluejets

Oct 5, 2014
6,067
Kaelin,
Found these "r/c boat esc" with forward /reverse and 6 to 12v operation.
Don't let the 320A throw you, it's just a max level ( mmm..... maybe on Mars I think)

https://www.ebay.com.au/itm/320A-6-...439964&hash=item3ae92d640a:g:VTYAAOSw6ShZVlHK

43mm x 29mm x 27mm

Just be aware that most of these esc units need to "armed" at the power-up stage.
This means the throttle (speed) needs to be initiated at full up after power-on and then reduced to zero setting for the controller then to work. It's a safety feature to avoid getting ones arms/legs chopped at power up from an rc set to max throttle accidentally.

Some may require "programming" also but it is normally a fairly straightforward process utilizing a series of led light flashes etc. Mainly to set things like brake on or off, set points ( maximum travel in reverse) for things like boats where max reverse would drown the poor thing.

Another thought was, that if your speed between motors is not required to be absolutely the same, you may get away with all 6 motors on the 1 controller. Just suck it and see I guess. Good luck.

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