I want to vary the speed of a 5v 170mA dc fan using a Transistor with a DAQ 6008. Could this be achieved?

[Thomas.F]

Hi, 

I would like to vary the speed of a DC fan(5V, 170mA) using a USB DAQ 6008 and a (BD139) Transistor.

I'm going to drive the fan using the voltage variations from the DAQ, and i'm using a 3 AA batteries. Could this be achieved? and with what kind of required changes?

[NIRebecca]

Hi Thomas,

Have you got any further with this application? 

You mentioned the use of 3xAA batteries; what are these being used for? Have you considered using the 5 V, 200 mA output on the NI USB-6008 as the power source?  Are you using the Analog Output channels to output a varying voltage to achieve the speed variations? You may find a few hints for this in the User Guide <http://www.ni.com/pdf/manuals/371303n.pdf>, the NI help Demos <http://www.ni.com/dataacquisition/videos> as well as other forum articles.

Let me know how you get on!

Rebecca

[Thomas.F]

Hi rebecca,

I referred the 5V, 200mA supply from the DAQ, however i realised it cannot be controlled and is a constant source once connected. Also, I tried using a linear amplifier motor driving circuit, but that too was in vain. i could not control the speed of the DAQ. 

Regards.

[Dennis_Knutson]

The 5V output obviously cannot be varied but one of the analog outputs can with software timing.