Control DC motor with ULN2803

Using Arduino Project Guidance
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I have acquired a few ULN2803s and want to use them to control DC motors. I will be using an arduino pro mini for each application.

I can find information on running one motor in one direction using the ULN2803, but nothing about changing direction of the motor. My application requires that the motor be reversable.

I think I can control the motor speed using a Pot to control the PMW pin output (need to do more searching on that, but at least I think I know how to do it).

What I can't get my head around is the reversal. My thought right now is to use a relay of some sort to switch the motor connections like I would do mechanically with a DPDT switch. I could use a switch, but that would defeat the purpose of a complete digital controller.

I could use a DC Motor controller from one of the supply houses, but to be honest, that way I don't learn anything other than how to wire things up.

So, any suggestions on how I might be able to do this kind of thing?

2

Goggle H-bridge.

3

LarryD,

Many thanks. A simple H bridge. I don't think that would work with the UNL2803 since the emiters are all connected to a common bus. So I would not be able to reverse current to the motor, at least that's what I think at first glance.

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Well, you can add some components to the 2803: relays, transistors.

But, yes a 2803 cannot be used by itself.

So goes learning about more advanced electronics :wink:

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larryd:
Well, you can add some components to the 2803: relays, transistors.

But, yes a 2803 cannot be used by itself.

So goes learning about more advanced electronics :wink:

Pretty much all higher learning. But we learn more from failures than successes. I would never have done this much research if it had been a simple task. I now know what this device is better suited for and in the future I may have some projects that require this kind of IC.
Thanks

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ov10fac:
But we learn more from failures than successes.

Don't know about that but when one tries to re-invent the wheel, it usually takes one on a round-a-bout road trip.

Anywhere one looks for reversing dc motor one will see reference to h-bridges all over.

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bluejets:
Don't know about that but when one tries to re-invent the wheel, it usually takes one on a round-a-bout road trip.

Anywhere one looks for reversing dc motor one will see reference to h-bridges all over.

H-bridge yes. All kinds of examples, but not many using the ULN2803, at least none that will allow both speed control and reversing of a DC motor. I have seen several using the L293 Quadruple H-Drive. I have some of these on order and I think I'll try to get something working with them.

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