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Project to control 12vdc heater circuits


#1

Hi All,
I’m working on a project to gain PC control over 6 DC voltage heaters used on a telescope.
I was planning on using 3 RoboClaw 7X2 boards to do this. I’ll be using the USB interface to gain access thru my PC. I have 3 questions that hopefully someone can help me with.
First, can these 3 boards be interdependently accessed while on the same PC usb port?
Second, can i use an input voltage of 12 volts and very the output voltage from 0dcv to 12vdc? Or does the input voltage need to be higher on this board?
Third, is there a better choice in boards to accomplish this task> each heater will not exceed 1.5a at 12vdc.

Thanks
DD


#2

Hello,

In general, it sounds like those RoboClaw motor controllers should capable of running a load like the heaters you mention. The maximum driver output voltage might be a few tens of mV less than the input voltage at the current you mention, but that generally does not seem like it would require a compensation in the supply. Also, it should be possible to control several of them on the same USB bus, but generally you would use something like a USB hub so they each have their own USB port. There is a packet serial mode on the RoboClaw that can allow more than one controller on a single serial port, but you might contact Basicmicro to see if that requires any additional hardware like a USB to TTL converter and how connections would need to be made for that.

There are many ways you might go about controlling heaters like that. Our High-Power Simple Motor Controller G2 18v15 should offer you a similar level of control to the RoboClaw and we have instructions for daisy-chaining multiple devices through a single serial port in the Serial daisy chaining section of the controller’s User’s guide. The cost for 6 channels (which would require 6 simple motor controllers) is slightly more expensive than the RoboClaws you mentioned, but pretty close.

If you are comfortable writing your own firmware for a microcontroller like our Arduino compatible A-Star programmable controllers or a switching frequency longer than a couple of seconds is sufficient to control your heaters, we might be able to offer other suggestions.

-Nathan


#3

Thanks Nathan,
That helps a lot. I appreciate the info. Looks like I’ll proceed with my project. The small amount of voltage drop over the RoboClaw will not be a big issue for my application. In which case I should be able to use my current power supply. I think I had better stay away from trying to write the code myself. So the RoboClaw solution with the software will work.

Thanks Again!
Don D.


#4

Hello All, I Have another question.
My project to control my telescope heaters is working out very well with one slight mistake on my part.
I accidentally created a short in my wiring which caused a problem on one of the three Roboclaw boards. This board is now unresponsive. When I try to power this board up it shuts down my power supply. My question is, can Pololu repair this board?
Thanks
DD


#5

Oh no! I am sorry to hear you damaged your RoboClaw. We do not manufacture that product, so unfortunately, that is not something we could help you repair. You might try contacting the manufacturer, Basicmicro, directly to see if there is something they can do to help. You can find contact information for them on their website:

http://www.basicmicro.com

-Nathan