Society of Robots - Robot Forum

Electronics => Electronics => Topic started by: BANE on June 23, 2008, 05:00:48 AM

Title: recommended DC H-bridge?
Post by: BANE on June 23, 2008, 05:00:48 AM

Hello, i was just looking a making my own h-bridge when i discovered this onehttp://www.hobbyengineering.com/H1918.html (http://www.hobbyengineering.com/H1918.html)

Has anyone used this one before or know how well it would work controlling two large printer motors?

Bane

Title: Re: recommended DC H-bridge?
Post by: bens on June 23, 2008, 01:11:51 PM

That depends on how much current your printer motors draw, and are they DC brushed motors or stepper motors?

Title: Re: recommended DC H-bridge?
Post by: BANE on June 26, 2008, 10:18:45 AM

there DC (not sure if brushless) and they draw about 800 mAh each (i tried them out on a 1.6 mAh bat and they work well)

Bane

Title: Re: recommended DC H-bridge?
Post by: ALZ on June 27, 2008, 02:27:53 AM

If the motor runs at 800 mAh then that h-bridge can not be used. A stall motor would take 5 to 10 times more current. The h-bridge can only handle 4 amps. In real life 2 amps would be more like it.

http://robotics.scienceontheweb.net

Title: Re: recommended DC H-bridge?
Post by: bens on June 27, 2008, 02:48:46 AM

Quote from: BANE on June 26, 2008, 10:18:45 AM

they draw about 800 mAh each

Is this stall current or no-load current?  If it's the latter (which I'm guessing it is since you describe these as large motors), what is the stall current?

- Ben

Title: Re: recommended DC H-bridge?
Post by: BANE on June 27, 2008, 06:34:22 AM

Does anybody know of a good website that has printer motor specifications?

Bane

Title: Re: recommended DC H-bridge?
Post by: bens on June 27, 2008, 12:20:14 PM

If you have a multimeter you can just hold your motor stalled (i.e. don't let it spin) and measure the current through it at a specific voltage.  Stall current will pretty much vary linearly with voltage.

- Ben