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UE9 for variable power output


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3 replies to this topic

#1 CryoEngineer

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Posted 25 February 2013 - 09:31 AM

I would like to use a UE9 to generate and vary the power for a heater. The maximum power required is 3W and I would need a 10 bit resolution. Is there another way of doing this than using PWM? I'm worried about the noise PWM may introduce.

#2 LabJack Support

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Posted 25 February 2013 - 09:34 AM

AC or DC? What voltage? As for your concern with PWM noise, what are you concerned about the noise getting into or bothering? With a heater you can do PWM slow or fast, so perhaps can choose a frequency that does not bother your other equipment.

#3 CryoEngineer

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Posted 25 February 2013 - 10:00 AM

There is some flexibility with regards to the voltage but it needs to be DC and no higher than 50V. There will be some very noise-sensitive cryogenic equipment installed in the vicinity of the heater: SQUID electronics and resistance thermometry operating in the pico-Amp range. Perhaps my noise concerns are exaggerated but I would still like investigate what my options are.

#4 LabJack Support

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Posted 25 February 2013 - 03:25 PM

I just notice now that you say generate and control. The UE9 can't provide 3W, so you need to provide a power supply. You provide some sort of power supply (e.g. linear 24V supply) and the UE9 controls that supply somehow.

To control the supply, you could just use an op-amp. Wire the op-amp in the non-inverting configuration, power it with the linear 24V supply, and provide the input signal with DAC0 on the UE9. You need an op-amp rated for the current, but there are plenty such as the OPA548:

http://www.digikey.c...089-5-ND/266166

Nice that it has a shutdown so you can totally turn off the heater.

This is a totally linear solution so should be quietest.


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