increase the speed of fan

[Shmuel Cohen]

Hey all (Sorry for bad English )

so that's the story .. I took my old CPU fan and connect the black and red wires to a 9V battery.

all good for now the fan speed was impressive but when i connected it to a 6V battery the speed was low much more.

so i opened it and saw a board with a 470 ohms resistor.

and i thought something like that

a 9V battery with 470 ohms resistor give me ~ 0.17W

so if i replace the 470 resistor with 100 ohms resistor and 6V battery i will get 0.36W

But in reality when i did replace the 470 resistor with the 100 ohms resistor i didnt saw any big change.

can anyone help me ? (i saw in YouTube some joule thief guides but i don't have the time or the money right now to order from eBay that 6V to 12V converter)

so.. someone have an idea for me ? how can i use a 6V battery and make the fan work like its on 12V battery ? (Or even 9v..)

 

[Cristi72]

Hello,

The fan' electric motor is a stepping type, so it needs a controller to properly work, and that controller is working best at its nominal rating (+12V, +5V, +24V, depending of the fan type). By lowering the input voltage, the controller don't have enough power to drive the fan. Also, by changing that resistor, you changed the controller's working regime, because that resistor acts as a current sensor (the controller "reads" the voltage on that resistor and drives the motor accordingly).

The best way is to use a DC/DC converter.

If you will use that fan in a PC, you can obtain some additional 7V or 9V from the PSU:

- 7V, between the yellow wire (+12V, use the + (red) from the fan) and the red wire (+5V, use the - (black) from the fan);
- 9V, between the yellow wire (+12V, use the + (red) from the fan) and the orange wire (+3,3V from the main 20/24-pin power plug, use the - (black) from the fan).

 

[Shmuel Cohen]

Hello,

The fan' electric motor is a stepping type, so it needs a controller to properly work, and that controller is working best at its nominal rating (+12V, +5V, +24V, depending of the fan type). By lowering the input voltage, the controller don't have enough power to drive the fan. Also, by changing that resistor, you changed the controller's working regime, because that resistor acts as a current sensor (the controller "reads" the voltage on that resistor and drives the motor accordingly).

The best way is to use a DC/DC converter.

If you will use that fan in a PC, you can obtain some additional 7V or 9V from the PSU:

- 7V, between the yellow wire (+12V, use the + (red) from the fan) and the red wire (+5V, use the - (black) from the fan);
- 9V, between the yellow wire (+12V, use the + (red) from the fan) and the orange wire (+3,3V from the main 20/24-pin power plug, use the - (black) from the fan).

Hey .i found this in eBay

http://www.ebay.com/itm/DC-LM2596-4-0-40-to-1-3-37V-LED-Voltmeter-Buck-Step-down-Power-Converter-Module-/261713002463?pt=LH_DefaultDomain_0&hash=item3cef4f7fdf

if i get it right , i can put an 6V and get up to 37V ?

 

[Cristi72]

Hey .i found this in eBay

http://www.ebay.com/itm/DC-LM2596-4-0-40-to-1-3-37V-LED-Voltmeter-Buck-Step-down-Power-Converter-Module-/261713002463?pt=LH_DefaultDomain_0&hash=item3cef4f7fdf

if i get it right , i can put an 6V and get up to 37V ?

It is something very wrong with that module; I mean, only 3$ for all thingy? Holy cow, that is cheap! Maybe the price is for the LM2596 only...

On a closer analysis though, that module is a step-down converter, so the output voltage is always lower than the input. You need a step-up converter:
http://www.ebay.com/itm/XL6009-Step-up-Power-Module-4-5V-32V-to-5V-52V-DC-DC-Converter-Perfect-/131410180258 Hurry, only one hour left and it's still bidding...

EDIT: forget about it, it's in China...

EDIT2: http://www.ebay.com/itm/1pc-Mini-2A-DC-DC-booster-Converter-Step-UP-Mobile-Power-Supply-Module-/291359881017 , from US (less powerful, but you can still drive 3 or 4 fans).

 

[Shmuel Cohen]

Hey .i found this in eBay

http://www.ebay.com/itm/DC-LM2596-4-0-40-to-1-3-37V-LED-Voltmeter-Buck-Step-down-Power-Converter-Module-/261713002463?pt=LH_DefaultDomain_0&hash=item3cef4f7fdf

if i get it right , i can put an 6V and get up to 37V ?

It is something very wrong with that module; I mean, only 3$ for all thingy? Holy cow, that is cheap! Maybe the price is for the LM2596 only...

On a closer analysis though, that module is a step-down converter, so the output voltage is always lower than the input. You need a step-up converter:
http://www.ebay.com/itm/XL6009-Step-up-Power-Module-4-5V-32V-to-5V-52V-DC-DC-Converter-Perfect-/131410180258 Hurry, only one hour left and it's still bidding...

EDIT: forget about it, it's in China...

EDIT2: http://www.ebay.com/itm/1pc-Mini-2A-DC-DC-booster-Converter-Step-UP-Mobile-Power-Supply-Module-/291359881017 , from US (less powerful, but you can still drive 3 or 4 fans).

Hey , i found this (the first you gave me dose not ship to my country (israel) and the second one is without the let screen and just the shipping is 10$

http://www.ebay.com/itm/DC-DC-100W-3-35V-12V-to-3-5-35V-Boost-Step-up-Module-Power-Supply-LED-Voltmeter-/400532004968?pt=LH_DefaultDomain_0&hash=item5d41916068

will it do the job ?

And i buy alot from china most of the time its good when its not i can return it

 

[Cristi72]

Hey , i found this (the first you gave me dose not ship to my country (israel) and the second one is without the let screen and just the shipping is 10$

http://www.ebay.com/itm/DC-DC-100W-3-35V-12V-to-3-5-35V-Boost-Step-up-Module-Power-Supply-LED-Voltmeter-/400532004968?pt=LH_DefaultDomain_0&hash=item5d41916068

will it do the job ?

And i buy alot from china most of the time its good when its not i can return it

That converter is a beast, go for it !

 

[Shmuel Cohen]

Hey , i found this (the first you gave me dose not ship to my country (israel) and the second one is without the let screen and just the shipping is 10$

http://www.ebay.com/itm/DC-DC-100W-3-35V-12V-to-3-5-35V-Boost-Step-up-Module-Power-Supply-LED-Voltmeter-/400532004968?pt=LH_DefaultDomain_0&hash=item5d41916068

will it do the job ?

And i buy alot from china most of the time its good when its not i can return it

That converter is a beast, go for it !

I bought it ! Thanks for your help !