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914World.com _ 914World Garage _ Simple electrical

Posted by: Elliot Cannon Jun 15 2011, 01:19 PM

I have a small 12v electric accessory motor on the car that I want to limit the rpm's on. I don't need to control the rpm, just reduce it somewhat. What's the easiest option to do this.
Cheers, Elliot

Posted by: SirAndy Jun 15 2011, 01:28 PM

QUOTE(Elliot Cannon @ Jun 15 2011, 12:19 PM)

I have a small 12v electric accessory motor on the car that I want to limit the rpm's on. I don't need to control the rpm, just reduce it somewhat. What's the easiest option to do this.

Add a inline resistor ...

If you want to control the RPM, add a inline potentiometer (which is just a variable resistor).

Posted by: nathansnathan Jun 15 2011, 01:41 PM

If you put a resistor inline on the power to a dc motor, it will slow it down.
I did it with computer fans, I had the link to a calculator, but it was for computer fans. There are calculators to tell you what resistance you need to take whatever voltage to whatever voltage that you can find. Make sure to get resistors that are rated at a high enough wattage.

Posted by: SirAndy Jun 15 2011, 02:11 PM

QUOTE(nathansnathan @ Jun 15 2011, 12:41 PM)

Make sure to get resistors that are rated at a high enough wattage.

Posted by: Elliot Cannon Jun 15 2011, 02:27 PM

So, if I want to cut the rpm in half, do I step it down to 6v? Can I get a resistor at Radio Shack? FLAPS? Thanks for the help.

Posted by: SirAndy Jun 15 2011, 02:43 PM

This might help:

http://www.sw-em.com/Vintage_Volvo_6V_to12V_conversion.htm

Posted by: kg6dxn Jun 15 2011, 06:44 PM

The VW world has been making devices to run 6V equipment from 12V sources for years. I would try one of their suppliers.

Posted by: 70_914 Jun 15 2011, 06:51 PM

Here is an option. Cheap and easy.

http://store.qkits.com/moreinfo.cfm/MX033