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Registered Member #2463
Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546
The nichome has a maximum rating in volts/M for a given color (glow).
It's easy to make it non-inductive. String it so that current one way, is the opposite the other way. Non inductive resistors can be made by folding the entire length back on itself, and then winding the folded wire in a coil with the feed point at one end.
As Proud Mary said "It could double up as a chip fryer"."
If you paid heed to the chip specs , this needn't happen.
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
radiotech wrote ...
.... String it so that current one way, is the opposite the other way.....
This is the case in some configurations for higher resistance, it doesn't seem to be having a detrimental effect at either ~30kHz or ~70kHz, but I'll run some more tests. (I do have some other problems with the circuit at the moment, though)
(The circuit is resonating at certain frequencies, but this resistor doesn't seem to be affecting it)
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
Ash Small wrote ...
radiotech wrote ...
.... String it so that current one way, is the opposite the other way.....
This is the case in some configurations for higher resistance, it doesn't seem to be having a detrimental effect at either ~30kHz or ~70kHz, but I'll run some more tests. (I do have some other problems with the circuit at the moment, though)
(The circuit is resonating at certain frequencies, but this resistor doesn't seem to be affecting it)
Q for an air-cored inductor wound from resistance wire will be low, so I would not expect much in the way of blatant resonance at any frequency.
Registered Member #193
Joined: Fri Feb 17 2006, 07:04AM
Location: sheffield
Posts: 1022
Er. "Homemade resistors are highly useful, but the problem with these is that once they start getting hot, the resistance may change drastically." The resistance would change by about 20% if you ran it at 500 C. probably not a major issue. A lot of alloys have temperature coefficients that are smaller then the 1/273 that's typical of pure metals. Considering that people use light bulbs as ballast resistors...
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
Bored Chemist wrote ...
Er. "Homemade resistors are highly useful, but the problem with these is that once they start getting hot, the resistance may change drastically." The resistance would change by about 20% if you ran it at 500 C. probably not a major issue. A lot of alloys have temperature coefficients that are smaller then the 1/273 that's typical of pure metals. Considering that people use light bulbs as ballast resistors...
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High wattage variable resistor
