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Is it possible to have a brushless DC fan with a cut in voltage of about 1.0 VDC and a voltage range of about 1.0 VDC to 7.0 VDC? I have been being told that I have to go with a brushed motor for this application.

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    \$\begingroup\$ I have a computer enclosure BLDC fan here, which seems to work fine from 1.5 Volts up through the rated 6 Volts. It does get noisy at low voltages, but I'd have to say 1-7 Volts might not be unusual. \$\endgroup\$ – Anindo Ghosh Sep 3 '13 at 16:31
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You could try to coax a brushless DC fan into 1 Volt startup by starting with the lowest voltage one you can find.Anindos comment implies that you can get close to where you want to be.Pull the fan apart and seperate the powerfeed to the lowlevel electronics which looks at hall position sensors and drives the bases of 2 NPN transistors in pushpull.The main powerfeed is easy to recognise as the red wire going to the CT connection of the stator windings.Take the lowlevel electronics powerfeed out using say an orange wire.Reassemble the fan.Organise a DCDC boost convertor that makes say 5V from 1V .There are heaps of chips around to do this .Now the fan should run slowly on 1V.If you want more speed then reducing the number of turns on each section of the CT stator winding will achieve this .I have DCDC conv that uses Standard silicone transistors that starts on 0.6 V and stops on 0.3V .I used to run two white leds of a candle powered TEG.I guess that you could use germanium transistors to go lower in Volts.If butchering the fan is a nono then run the fan of a DCDC convertor which will be cheap and more reliable than going to brushes if continious operation is envisaged.

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