12v variable slide resistor

[cooldog]

okay guys i was wondering if i have a simple circut of a 12v motor and a car battery (12v) with a switch and i put a 12v variable slide resistor in the circut would i be able to control the motors speed?

if what i am saying is true does anyone know where to get a 12v variable slide resistor?

[TrickyNekro]

yes there is....
Google for LM317 speed controller

[cooldog]

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=497-3466-5-ND

do you think this is will work?

[Razor Concepts]

Depends on how many amps your 12v motor will pull. The one you listed is good to 5 amps

[cooldog]

would that be max 5 amps from the battery or that my motors draw

[Soeren]

Hi,

The LD1585 will only do for a small('ish) motor.
It can handle around 2W un-sinked and with a large heat sink around 25W tops.

Regulating it to eg. 6V will make it drop 6V (actually a bit more, since the terminal voltage is more than 12V).
Un-sinked this equates to 2W/6V=333 mA
With perfect heat sinking it will be 25W/6V = 4,17A

Regulating the output further down will only worsen this to around 166 mA and 2,1A respectively.
(It's all in the datasheet).

[Trumpkin]

would that be max 5 amps from the battery or that my motors draw

That your motors draw.

[Soeren]

Here is something far better http://www.dprg.org/tutorials/2005-11a/index.html

[cooldog]

Here is something far better http://www.dprg.org/tutorials/2005-11a/index.html

that looks like a good circut however i looks like it need a lot of external parts

i would prefer just a off the shelf ready made circut

would that be max 5 amps from the battery or that my motors draw

That your motors draw.

i think that i am moving more toward this option

The LD1585 will only do for a small('ish) motor.

thanks anyway but i would like to use something for a bigger motor so i can use it in future projects

[Soeren]

Hi,

The LD1585 will only do for a small('ish) motor.

thanks anyway but i would like to use something for a bigger motor so i can use it in future projects

Then you really need a PWM circuit, as a linear solution has too much loss (i.e. heat).

You should be able to buy a ready assembled PWM solution, although it might be a bit expensive - perhaps you can advertise for someone here to build the circuit for you, so that you just have to connect power, motor and a potentiometer (eg. your variable slide resistor).
If you want to take that route, stating where in the world you live is not a bad idea.

[cooldog]

well i live near toronto canada