How to control speed of fan

[8]

i can send a signal to turn on fan when over heat and turn off the fan when cool.

However, i want to know how can use labview to control speed of fan.

My laview is 8.0, PCI-6221, BNC-2120, K-type temp sensor.

[devchander]

That would depend on what sort of a Fan Motor you want to control

What Fan are you using??

One possibility is with a suitable intermediate signal conditioning/control circuitry you can use the AO channel ( variable in range of -10 to 10 V) to control / vary the speed of motor

[8]

i am using common CPU fan. The fan no RPM sensor only two wire. i using AO to send a low voltage singal to turn on the transistor, let the highter current pass the fan. i only can do this by labview and i want to control the speed.

[Elizabeth W]

Could you clarify what you need help with as far as the LabVIEW programming goes?  Is it simply that you need help getting started with programming your DAQ card's analog outputs in LabVIEW, or are you asking for help with more complex concepts like programming control algorithms?

Thanks!