Arduino Forum

Forum 2005-2010 (read only) => Hardware => Interfacing => Topic started by: dwyer2bp on Jul 08, 2010, 09:29 am

Title: H Bridge help
Post by: dwyer2bp on Jul 08, 2010, 09:29 am
Well, I am currently attempting a build at an h-bridge to run a DC motor. I have 4 N-Mosfets on the way, and I'm trying to prepare other components to use them.

I need help understanding/ choosing Mosfet drivers for building a 4 N Channel H bridge. My mosfets of choice are: IRFZ44E
http://www.hvwtech.com/products_view.asp?ProductID=895

I also ordered this chip, thinking it could come in handy: ULN2803A
http://www.hvwtech.com/products_view.asp?ProductID=327

The DC motor is to be controlled via arduino. The motor has proven too much load for the L298N chip in parallel;

I've been reading a lot on mosfets: Is it possible to use the arduino 5V/40mA outputs to drive these?

Thanks!
Title: Re: H Bridge help
Post by: Grumpy_Mike on Jul 08, 2010, 09:47 am
Quote
Is it possible to use the arduino 5V/40mA outputs to drive these?

Well it's not the best FET for making into a controller. It needs 10V to turn it fully on. It will be reasonably hard on at 5v but you are limited to about 7A which is far short of the 48A headline figure.

Also is the H-bridge going to just switch the motor at 5v or do you plan to use something higher? If so you will need driver circuits on the gates anyway. I would also include a 100R series resistor in line with the FET gate to protect the arduino from over current pulses.

Do you have a schematic of what you are going to build?
Title: Re: H Bridge help
Post by: tkbyd on Jul 08, 2010, 12:12 pm
With all the Good Things to do out there... why reinvent THIS wheel?

Wouldn't the....

http://www.pololu.com/catalog/product/713

TB6612FNG Dual Motor Driver Carrier $8.45
...can independently control two bidirectional DC motors or one bipolar stepper motor. A recommended motor voltage of 4.5 - 13.5 V and peak current output of 3 A per channel (1 A continuous) make this a great motor driver for low-power motors...

... do what you need?

(I'm one of the first, by the way, to reinvent wheels... when there isn't a cheap one on sale yet. How many minutes of your time does it take to go past $8.45? And no, I don't have anything to do with Pololu!)
Title: Re: H Bridge help
Post by: dwyer2bp on Jul 08, 2010, 03:13 pm
Grumpy Mike:
I am utilizing an old RC Car which ran it's 'drive' motor straight off of a 7.2 volt battery which I'm still trying to use. (The old car used Relays).

I have a basic schematic that I am trying to build off of. I've made P/N channel h bridges, but never full N. If these transistors won't work, I'll find them a use somewhere else and maybe you could suggest a better way to build this. If it comes down to it, there is a motor driver at spark fun for 40$ that I'll spring for if I can't build my own to handle enough current for this motor. Using the L298 I measured more than 4 A being drawn at constant supply that wouldn't even run my motor with enough torque to move the car as fast as relays did.


tkbyd: THanks for the suggestion, however I do not believe that will handle the current my motor will require. THere is a 40$ Pololu driver I'm thinking about at Sparkfun.com that would most likely work, but I wanted to gain experience in this direction

Thanks!
Title: Re: H Bridge help
Post by: tehjrow on Jul 08, 2010, 08:41 pm
I attempted to build an H Bridge for my RFID door project..... It was over my head.

I folded and got this:
http://www.sparkfun.com/commerce/product_info.php?products_id=9670

And never looked back.  It's so freaking easy to use.
Title: Re: H Bridge help
Post by: dwyer2bp on Jul 08, 2010, 09:15 pm
I've tried the L298 alread: in parallel mode none the less, but I need a driver capable of drawing over 4 A constant, and almost 5A spikes (as far as I could detect with my Amp meter).

Thanks though! I will be using that chip for my steering circuit since I prepared my own board already.

What type of motor were you using for your door? (I assume it was to either open it or unlock it)
Title: Re: H Bridge help
Post by: tkbyd on Jul 09, 2010, 12:53 am
For an "H bridge" capable of handling large currents/voltages, you can do one with relays...

http://sheepdogsoftware.co.uk/sc1am.htm