Having ordered this board yesterday I started reading the troubleshooting guidelines in the online manual https://www.pololu.com/file/0J59/smc05a_guide.pdf. One item struck me as odd, and I wasn’t sure if this was just for troubleshooting or if it is a requirement. My assumption is the former, but I thought I would run it by you guys:
I plan on using a 11.5 volt LiPo pack regulated down to 6 volts using an LM317T that can deliver 1.5 amps. My motors don’t exceed 500 mA. This shouldn’t be a problem, right?
Adding your own regulator to the mix can cause all kinds of problems, so I generally don’t recommend it unless you know what you’re doing. By the way, given this plan of yours and your 500 mA motors, I think the qik 2s9v1 would be much more appropriate. With that controller, you could skip the regulator and just not give your motors speed commands higher than 50%.
Thanks Jan. The other one is already in the mail, so I have to use what I (will) have.
Plus, there are times I need to get this motor down in the 2-3 volt range so I think this one is the one for me.
I’ve been out of the electrical game for awhile but I have an EE degree, so I know “somewhat” what I’m doing unless there’s something very unique about regulators that this board doesn’t like.
Is it the current response that is the concern? I have some larger (1000uF) caps I can put on the 6V side to account for that if needed. Should there be a diode added to handle spikes?
I am stuck with my current battery choice, so running 11.5V through a board that is not supposed to have over 7 is an issue, obviously.
Can you provide any details as to what the concern is?
The general concern is the large and varying load. Big caps should help. What kind of diode are you talking about for what kind of spikes? That sounds like the opposite of what you need, at least for the motor controller. A battery smoothes out any spikes that the motor might want to put on the supply; without it, you could more readily get higher-voltage spikes that could be damaging to the controller. If you are thinking of the diode to protect the regulator, that’s some of the stuff I’m talking about regarding the power supply design not necessarily being easy. However, your motors sound quite small, so the big caps should go a long way to cover any of these potential issues.
Yes, I meant for regulator protection. I’ll slap some large caps in there to handle any high current needs or back current that may get produced if the motors are reversed for whatever reason. This is a sumobot, so it may have to go back suddenly if it goes past the edge of the dohyo.
Just wanted to say I followed the source code instructions (for Arduino) in the link I posted and I was able to get the controller working with great success. I used the Arduino to power the 5V voltage source and a 6V battery pack for the motors. Worked great first time.
This controller saved me so much space I had room for additional components on my protoboard.
