Needed: Rheostat designed for 12VDC use


IronBeltKen

IronBeltKen

Lazy Daydreamer
I'm setting up a motor mechanism to spin a Walthers rotary coal dumper using twin 12VDC motors with reduction gears. Up to this point, I've tested the functionality of it by connecting the motors to a leftover MRC DC power pack that I use whenever I want to test DC locos that have been newly-purchased from a private seller, and confirmed that everything works fine. Now I'm ready to run the wiring from a dedicated 12V wall-wort to the mechanism, with a rheostat to control the speed.

The problem now is that I don't know exactly what to look for; every time I do Google searches on "rheostat" I get a bunch of results for 120VAC devices used as light dimmers, stove fan speed controls, etc. If Radio Shack still existed I could just go there and somebody would help me find what I need - but they are long gone. So...can anybody here tell me what kind of rheostat I can connect in series, to control these 12V motors applying 0 to 12 volts?

...thanks!
 
the voltage doesn't really matter ... it's the current to passed through the pot that's important
 
If you search on ebay for a;

High Power Wirewound Potentiometer,​

you will find what you need.
However, selecting the correct ohmic value is difficult.
The coal dumper motor ohms could be a good starting point.
Better to use one of these

www.ebay.com

DC 6V- 28V 3A PWM Motor Speed Varible Regulator Controller Switch Module | eBay

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wvg_ca said:
the voltage doesn't really matter ... it's the current to passed through the pot that's important
Click to expand...
And that's what makes this confusing for me. I don't know how much current the motors are drawing at the different speeds, and I don't have a multimeter to hook up where I can check it. I selected the one I linked to in my reply to Terry (above) because the people were using it in similar applications to what I'm trying to do.
 
the DC-DC adapters that you [the op] ordered should work, they won't give you fine control like a rheostat will, but they will give somewhat coarse control by varying the output voltage .. might be close enough ?
 
wvg_ca said:
the DC-DC adapters that you [the op] ordered should work, they won't give you fine control like a rheostat will, but they will give somewhat coarse control by varying the output voltage .. might be close enough ?
Click to expand...
I wired them in this weekend, and they do work. However, they don't have the '+' and '-' polarity markers on them, so I almost burned one of them out before I discovered that I had put the input wires in backward. More about that in a later post...
 
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