# multiple motor h bridge?

I see a lot of h bridge diagrams on the internet, more or less like this:

If I wanted to connect let's say 4 motors in h bridge configuration while using the same power supply (12v) for all 4 of them and would also like each motor to be able to work independently, what do I need to do? Is this feasible (without a motor driver IC)? Would hooking up more than one h bridge to the same power source affect the current that goes through each motor? If so, how to remedy that?

• if u use the above way u cannot run even two motors independently! Dec 22, 2015 at 8:56
• @Jasser: Why not? Dec 22, 2015 at 9:47
• I meant with one hbridge @EM Fields Dec 22, 2015 at 10:04
• I guess I wrote it weird. No, I was considering that each motor has their own h bridge. Dec 22, 2015 at 12:51

1. If you want 4 independent motors then you need four independent H-Bridges.

2. If you have a 12V source that can supply current to all 4 simultaneously then there's nothing to worry about. Hook them up in parallel and get a controlling circuit (MCU, timer, etc.)

3. If your 12V supply can't provide enough current to drive all 4 motors then you need to ask more questions:

3a. Do you allow default coasting (non-tracking state)? If yes, you can use that state to save power and then simply apply power to each of the motors out of phase with one and other (i.e. if you can drive two motors at a time, then only drive two at a time and have the other two coasting).

3b. If you don't allow coasting then the solution is get a bigger power supply.

• Can you explain or give resources to coasting? I believe this is a new concept for me... And how can this be achieved with an MCU (like Arduino)? Dec 22, 2015 at 13:27
• Stepper motors must have power applied to them in order to guarantee their position. If you have all 4 transistors in cut off, then there's not electromagnet holding the motor in position. This is known as "Coasting." As for how to achieve this using an Arduino, that is best left to another question. Please re-ask so that others in the community have a chance to offer their support.
– Dave
Dec 22, 2015 at 15:45