H Bridge and DAQ 6008

[samuelaguilar990]

Hi,

So here is what I'm trying to do: 

I fabricated a robotic arm which is composed of 3 DC motors; one on the shoulder, one on the elbow and one on the claw. These motors are small but have high torque. For this matter, I need to invert the direction of the motor and I wanted to control it with LabVIEW. So the coding is not a problem, but a hardware issue. I'm using the NI USB-6008, I know, it is not the best device to use for this purpose neither is it the strongest, but it's working out for me. So, for polarity inversion I used an H bridge with two TIP32 and two TIP31, for the signal coming from the DAQ I have, +5v from DAQ>a 1K resistor>2n2222 PNP transistor>another 1k resistor which goes to the H BRIDGE. This configuration is repeated for the other signal which gives me the other direction. So I got that working and powering the motor with 12V DC battery. So my question is, 12V isn't enough to move the arm, and the motors, though they are small, apparently they are up to 40V, so, can I use 36V to power the motor? Would it damage the NI USB-6008??? Would it fry my transistors? (well actually the main reason I used the TIP31 and 32 is because they are high potency transistors, I tried out the ULN2003 and it heats like a summer day in the desert) and, is the value of the resistor which comes from the 2n2222 to the h bridge proportional to the value of the voltage powering the motor??? That is, if voltage increases, the value of the resistor increases proportional to the voltage (more like 12V=1kohm, 24V=2kohm, and so on...) so please please I need help on this one before just firing it up I would like some input so that I don't fry the transistors since they were kinda expensive....Thank you! (I can always use 12V relays though, but that would be too much work!  )

[kellis.wiseman]

Hey samuel, 

I don't really know enough about your circuit to answer a lot of the questions about the individual components (you might try consulting the specifications for the TIP31 and TIP32, and the other components). You could also post a schematic of your circuitry in hopes that someone from the community will be able to answer your questions. 

I can, however, help you with your question about our product: the USB-6008. Since it is a Category 1 device, it should not be given a power source greater than 30V (consult the USB-6008 Specifications Sheet), so do not use a 36V power source. 

Best of luck with your application!

~kgarrett