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Author Topic: 12v variable slide resistor  (Read 2470 times)

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Offline cooldogTopic starter

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12v variable slide resistor
« on: January 03, 2009, 07:45:17 PM »
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?
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Offline TrickyNekro

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Re: 12v variable slide resistor
« Reply #1 on: January 03, 2009, 08:26:27 PM »
yes there is....
Google for LM317 speed controller
For whom the interrupts toll...


P.S. I've been inactive for almost a year... Don't give promises but I'll try to complete my tutorials. I'll let you know when..

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Offline cooldogTopic starter

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Re: 12v variable slide resistor
« Reply #2 on: January 03, 2009, 10:03:51 PM »
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Offline Razor Concepts

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Re: 12v variable slide resistor
« Reply #3 on: January 03, 2009, 10:07:39 PM »
Depends on how many amps your 12v motor will pull. The one you listed is good to 5 amps

Offline cooldogTopic starter

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Re: 12v variable slide resistor
« Reply #4 on: January 03, 2009, 10:18:43 PM »
would that be max 5 amps from the battery or that my motors draw
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Offline Soeren

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Re: 12v variable slide resistor
« Reply #5 on: January 04, 2009, 09:42:26 AM »
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).
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Offline Trumpkin

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Re: 12v variable slide resistor
« Reply #6 on: January 04, 2009, 09:43:06 AM »
Quote
would that be max 5 amps from the battery or that my motors draw
That your motors draw.
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Offline Soeren

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Re: 12v variable slide resistor
« Reply #7 on: January 04, 2009, 09:45:04 AM »
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
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Offline cooldogTopic starter

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Re: 12v variable slide resistor
« Reply #8 on: January 04, 2009, 10:04:57 AM »
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

Quote
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

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Offline Soeren

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Re: 12v variable slide resistor
« Reply #9 on: January 04, 2009, 10:37:50 AM »
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.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline cooldogTopic starter

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Re: 12v variable slide resistor
« Reply #10 on: January 04, 2009, 12:34:33 PM »
well i live near toronto canada
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