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DC Fan control using NI - DAQ 6009 analog output

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moreins

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Hey guys

I have a DC fan that works between 3 and 10 volts and needs 1A. I need to control it using a daq 6009 by varying the output voltage at the analog output of the daq. i am well aware that the daq cannot give the necessary current that the fan needs, so i need a power stage that isolates the daq and the fan so i dont damage the daq (which has only 5mA on its analog output)

can anyone give me some ideas of what should i use to give the current i need to use the fan? i heard about a current buffer but i have no idea about it



thanks!
 

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pauloynski

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Connect a darlington transistor at the output of the DAQ (may be a TIP122) configured as voltage follower. Probably you´ll need to increase the amplitude of the signal too (use an op-amp) to do that. Also you must add some protection (a snubber) and provide an external power suplly.
 

moreins

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hey! thanks for your reply
since i will be working with DC all the time, and the daq gives me the voltage (not the current) that the fan needs (3 - 10 Volts), do you really think i should use a opamp and a snubber??

thanks!
 

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pauloynski

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If the DAQ output voltage is enough you don´t need to amplify it. A snubber (RC circuit or something else) is allways necessary when driving inductive loads.
Regards
 

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