Run DC Motor Using DAQ 6221

[CooLDuDe]

hi frnds,

I want to Control DC Motor using NI DAQ Card 6221. My problem is that when i connect the motor to daq card, its not rotating, I have check the voltage at the terminals of DAQ card, its giving me the required voltage, But the motor is not Driving. I have also check the specification of DAQ 6221. there its written the Output Current Drive =+- 5mA.

So maybe that why i cant drive the motor, So now what can i do?

Can anyone plz suggest me??

Thanks in Advance

[george seifert]

QUOTE (CooLDuDe @ Apr 8 2009, 09:12 AM)

hi frnds,

I want to Control DC Motor using NI DAQ Card 6221. My problem is that when i connect the motor to daq card, its not rotating, I have check the voltage at the terminals of DAQ card, its giving me the required voltage, But the motor is not Driving. I have also check the specification of DAQ 6221. there its written the Output Current Drive =+- 5mA.

So maybe that why i cant drive the motor, So now what can i do?

Can anyone plz suggest me??

Thanks in Advance

The first step is find out how much current drive your motor needs. If you have a power supply with a meter on it that will help with this step (hopefully your supply will have enough drive). If the supply doesn't have a built in meter then connect a DVM (set to measure current) in series with the motor. Now armed with that knowledge you can figure out where to go next.

[Justin Reina]

Hello,

Hook the motor up to a power supply at 5V, and observe the current. How does this compare to the DAQ's limits?

Solution (probably):

Use a 'buffer' between your low current circuit (DAQ) and your high-current circuit (Motor). Some people call this a 'driver'. Maybe try something like this:

http://en.wikipedia.org/wiki/Darlington_transistor

http://search.digikey.com/scripts/DkSearch...e=296-1979-5-ND

Best of Luck,

Justin

*This is an electrical-type prob. Maybe find someone at your work/school to shed more light on it. Kind fun stuff, I think

[PaulG.]

I use a 6221 and I'll go along with everyone else here: it probably does not have enough current to drive the motor directly. But don't worry. This is a learning experience for you. 5V is 5V, but not necessarily when it comes to current output. When working with logic outputs remember one thing: TTL outputs, i.e. outputs you want to control "things" (motors, displays, rocket motors) will almost never be driven directly. Check with the motor manufacturer for their recommendations for driver chips. That would be the simplest way to go. But if you want to get hands-on, fun and dirty use MOSFETS to drive your motors. It's worked for me. Have fun.

[CooLDuDe]

FIRSTLY THANKS FOR REPLYING

Actually my motor drives current of arount 20 mA. When see the specifications its given 5mA. But i dont want to use other hardware as such. Is there any other solution or suggestion for me. Or any other NI supporting DAQ or Whatever(except NI 9505, it requires LabiewFPGA), which can drive my motor.

Thanks

[Justin Reina]

Hello,

20mA? Could you post a link to it, it seems small. If it is this small, any opamp would work configured as a buffer. A 741 may do the trick.

Chip: http://search.digikey.com/scripts/DkSearch...me=LM741CNNS-ND

Example: http://www.eecs.tufts.edu/~dsculley/tutori...ps/opamps5.html

-Justin

[CooLDuDe]

Thanks a lot for giving suggesstions,

It worked by using LM 324 as a buffer,

i tried by opamp ca741, it not worked,

but by LM 324 it worked fine....

thank once again

[Justin Reina]

Cool! Glad to see it worked.

-Justin