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Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
I knocked this up this afternoon, using the heater element from a fan heater.
It is adjustable from 2Ω to 110Ω, just by re-arranging the tapped connections.
It was good for 1kW in the original application, so shouldn't have any problem running at 100 watts or more.
I'm using it as a variable current limiting resistor while running some tests on my 2N3055 circuit, but I'm sure I'll find plenty of other uses for it too.
Registered Member #1225
Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253
Homemade resistors are highly useful, but the problem with these is that once they start getting hot, the resistance may change drastically. However it is surely just a nichrome wire, which is what normal resistors are. I think 100w may be fine and the resistance won't vary too much, though. If it does, just blow a fan over the elements, or even soak it in some deionized water or oil.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
I used to use Hair dryers for this purpose, Though they did change resistance as they got to a final temp, then flattened out, often for precision i'd measure the V and I simultaneously since the Absolute resistance value usually doesnt matter much.
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
Forty wrote ...
."hungry? need an inductor? sick of fiddling with different resistors? then look no further..."
"feed, impede, succeed!"
There is a reason why this thread is in 'general chatting'. It's not to be taken too seriously, but it didn't cost anything and it 'seems' to have plenty of uses, not least as a current limiter.
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
Ash Small wrote ...
Forty wrote ...
."hungry? need an inductor? sick of fiddling with different resistors? then look no further..."
"feed, impede, succeed!"
There is a reason why this thread is in 'general chatting'. It's not to be taken too seriously, but it didn't cost anything and it 'seems' to have plenty of uses, lot least as a current limiter.
I do appreciate the humour, though.
The silliness is all down to me, Ash. It's just that when I came to respond to your post, I was also thinking about going down to the quay and buying a piece of plaice to make fish-and-chips with, and the two things somehow became confounded in my mind.
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High wattage variable resistor
