Potentiometer question

xiao_haozi

xiao_haozi

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Okay this isn't for specific arcade equipment... but rather for a piece of equipment here in my lab.
But I thought I would post my question here since it is more about potentiometers in general and thought that any feedback might be handy to have in the tech section for various projects anyway. So if this needs moved to another forum.. I appologize ahead of time...

On to the question:

I have an OLD coil style potentiometer.

It's shorting out up to 50% output... then is fine.
I can see actual little sparks coming out of it.

It is marked 1100 ohm .15A ...

Could I just throw in a 1k ohm newer style linear pot?
Would I assume .15A is the output or the maximum input it can tolerate... seems to be coming right from the ac in.
 
channelmaniac

channelmaniac

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That is a high wattage pot. If you replace it with a simple carbon contact type (normal low current type) then you will smoke it.
 
xiao_haozi

xiao_haozi

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Ah okay...thanks RJ...

So are these still easily obtainable through something like jameco?

And if so is there something I should specifically search for in terms of the type of pot?
 
xiao_haozi

xiao_haozi

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What kind of Wattage rating do you think I would want? Seems that is what they often have them listed by... resistance range and wattage rating (2 was the highest I could find on jameco site).

Here are two shots of it:

pot1.jpg


pot2.jpg


Wouldn't something like this here be sufficient at 2 watts?
 
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ttooddddyy

ttooddddyy

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P= I squared x R
P =0.15 x 0.15 x 1100 = 24.75 Watts

You really need a wire wound pot, I notice the fiberglass coated wires to the pot - must get real hot around there.
 
xiao_haozi

xiao_haozi

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ttooddddyy said:
P= I squared x R
P =0.15 x 0.15 x 1100 = 24.75 Watts

You really need a wire wound pot, I notice the fiberglass coated wires to the pot - must get real hot around there.
Click to expand...

Ok I'll have to keep looking around then.

Yeah I don't think it really gets that hot, just high power coming through there, but just use general wiring for these guys. The other style has a heating coil in there that also has a similar pot. This one just goes to a motor and controls the speed of rotation for a magnet.

There is a spot right in the middle there where the wires are gone and so we are getting a small spark form in there below that spot (anything less than about 50%). So maybe I'll figure out a way to temporarily repair the spot until I can find a suitable pot to replace it...
I wonder if I can lay a thin layer of solder across the bare spot.
 
xiao_haozi

xiao_haozi

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Alright ordering that one now.

Here's to hoping this thing doesn't burn down the lab! :loco:
 
ttooddddyy

ttooddddyy

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Make sure the fire extinguisher is charged, these things get hot. You never let on what it does ?
 
xiao_haozi

xiao_haozi

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ttooddddyy said:
Make sure the fire extinguisher is charged, these things get hot. You never let on what it does ?
Click to expand...

hhahaha yeah hope we don't have to worry about that....


It's a stir plate. Big magnetic bar is spun by a motor which is attenuated by that pot.
You can then throw a magnetic bar into a beaker or other container and place on the plate and keep your solutions stirring.

Usually in two varieties with one having just the stir mechanism and the other also containing a heating element so you can heat and stir. This one is the former with just a stir mechanism... so not sure what all the coating of the wires and such. But they are so expensive, figured for 10 dollars if this can fix it we are golden.

Anything to keep in mind before hooking up? Never worked off straight AC in...
 
xiao_haozi

xiao_haozi

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Just don't want to cause a small fire and have the sprinkler system kick in...
probably should just take home to the basement so i can spray with an extinguisher should the need arise....
 
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