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Registered Member #2893
Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242
I bought a 90 ohm 200W 3 terminal variable resistor off craigslist for $20, but I'm not sure what I can do with it; it's such a low ohmic value. It's huge and made of ceramic, so it could probably be pushed to 500 watts without a problem. If you want a pic just ask.
Right now I just have it attached to a 12v lamp and one of my giant batteries as a fancy nightlight.
Registered Member #2628
Joined: Fri Jan 15 2010, 12:23AM
Location:
Posts: 627
I dont see too many applications for this beast, but other then some fancy/messing around purposes, its just the thing..
I really dont have an idea, maybe a high powered low voltage supply? (5V and under at 10-20A or more) but a picture would be nice, so others can admire this thing
Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3141
While thinking of a use; - sqrt(90 x 200) = 135 V dc/rms maximum .... 120 Vac mains - an eBay buyer may be interrested.
. a crude motor speed controller . a current-limiter for electrolysis/electroplating - with a bridge rectifier . a variable load for testing power supplies etc.
Registered Member #1875
Joined: Sun Dec 21 2008, 06:36PM
Location:
Posts: 635
Maybe you could rewind it with copper wire and make a variable inductor? That might be more useful for experimentation when you need to determine an ideal inductor value for some random application.
I use more high powered inductors than high powered resistors, personally.
Registered Member #2099
Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1716
Grenadier wrote ... I have a 90 ohm 200W 3 terminal variable resistor, but I'm not sure what I can do with it; it's such a low ohmic value. It's huge and made of ceramic, so it could probably be pushed to 500 watts without a problem.
The 200W rating takes into account the ability of its materials to work satisfactorily at "high" temperature for long periods of time. The part looks like it would be comfortable with a temperature rise of 150 degrees C above room temperature. Screw terminals insure that wires won't fall off when solder melts.
Wattage probably needs to be derated if airflow is blocked or ambient temperature is high; conversely, forced air cooling will allow operation at higher than rated wattage.
Registered Member #2893
Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242
Well I just sent 400W though the thing and it reaches 150* at that point. I don't think I want to push it any more. Though if I really wanted to I could make it so the wire glows red. I'm sure it could handle it since it's nichrome wire wrapped around porcelain.
As for the variable inductor idea, I don't have an induction meter so I'd have no clue what the inductance is. Cool concept though. What would really be neat is using it as a tuner for a radio.
Registered Member #1875
Joined: Sun Dec 21 2008, 06:36PM
Location:
Posts: 635
You could do some calculations to get a ballpark value for the inductance. Ballpark is good for devices of a variable nature. :)
Reminds me of a kit I made when I was very little, which was probably what planted an interest for electronics deep into my psyche...
If you do go with the inductor idea, you might want to do something more along the lines of transmitting than receiving, given its power capabilities...
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What can I do with a 200W rheostat?
