Can you control a peltier chip with DAQPad-6015?

[remotecntrl]

Hey,

This is a pretty straight forward question.  I have been controlling a DC power supply with a labview code I wrote up.  Then my coworker told me it was possible to control the peltier chip directly through the DAQPad.  Is that true?  If so, how would I control it to ramp up or down at a predetermined rate.

Thanks,

Katie

[Jason_D · Accepted solution]

Hi remotecntrl,

What kind of peltier chip is this?  What kind of inputs does it have?  Can you give me any additional info you know about the device?

It would be possible to generate an analog output that could emulate the sinusoidal ramping you desire.  If this chip can be controlled by this signal would be based on the chip and the possible ways we can control it.

[remotecntrl]

Hi Jason

The peltier chip is the CH-38-1.0-0.8 from TE Tech, Inc.  Here is the info about it: 

http://www.tetech.com/Peltier-Thermoelectric-Cooler-Modules/Round-Center-Hole.html

the spec sheet is here:  http://www.tetech.com/temodules/graphs/CH-38-1.0-0.8.pdf

I am going to control the chip with voltage.  The other option is through current. 

Thanks,

Katie

[AnalogKid2DigitalMan]

The TEC requires current and power that well beyond the range of the DAQ device. You could use the DAQ to control your power supply in current or voltage mode. You may need a temperature feeback device if you want to maintain or ramp at a given temperature profile.

-AK2DM

[acanivell]

The main problem I am facing for my Peltier control is the current consumption.

My peltier consumes 1.25A at 5Volts, and I have found no NI input/output card able to drive this current,except for this NI9505, which is available only in Crio, not in SCXI.

Did you manage to find a solution for this?

Álvaro

[Now_With_Underscores]

I would recommend using a voltage follower, which can be purchased from most electronics stores.  They are about 5-20 dollars, depending on how much current you want to source.  What you do is hook the AO of our card to the input and then the output follows said input voltage via an opamp.  The additional current then comes from an external power supply, but is controlled by the follower.

A more complex method (but still elementary) would be to use a transistor or mosfet and control the base/gate with the AO.

[acanivell]

Thanks John

Yes, I already thought about it,  but I wanted to avoid adding external elements to my CRIO configuration.

I would like to keep everything inside the CRIO platform. Then I thought I could maybe put the voltage follower inside an empty CRIO module shell.

But if possible, I would prefer just using a CRIO device that does the trick without any add-ons. The 9505 looks fine,but I am not sure that I can drive it in DC instead of using PWM.

Does anybody know if I can do that?

[JeffL]

Hi acanivell,

The 9505 would require having an external power supply, so you're not going to be able to escape having something hanging off the device.

[acanivell]

I see John, you are right, I did not see the external power requirement for NI 9505 (I think this is not clear enough in the manual).

Then, in any case, an analog output module (such as 9263) plus a voltage follower would be cheaper than a NI 9505 plus a power supply.

In addition, I am not sure that one can actually drive a 9505 in DC, not in PWM. And then even if I could, I would need to switch the power supply polarity when I need to change the polarity, isn't it ?

[JeffL]

It would be far simpler to just go with the voltage follower. The 9505 is a motion control product.