5W resistor ?, marked 0.1ohm, 5W

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I cracked the white outer ceramic block and instead of wire/strip around  
a ceramic core, what looked exactly like a 2W metal oxide resistor,  
complete with brown,black,silver bands  .
Does wrapping a 2W resistor in fire-cement and preform ceramic hollow  
block, make it 5W?

Re: 5W resistor ?, marked 0.1ohm, 5W
On 6/6/17 8:41 PM, N_Cook wrote:
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Sounds more like our overseas friends creative component marketing.

Re: 5W resistor ?, marked 0.1ohm, 5W
On Tuesday, June 6, 2017 at 8:41:15 AM UTC-4, N_Cook wrote:

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They're not rated in amps, but watts.  Soooooooooo..... If you can sink off enough heat you can raise the wattage rating of a resistor.  What I don't know is whether you can get a two watt resistor to safely dissipate 5W with the package you describe.

Sony used a lot of 0.1 ohm ceramic encased resistors as fuses, but these were encased for fire retardence and eliminated the loud pop/snap a regular 0.1 resistor made when the mosfets after them shorted.

If there's another one like it in the circuit you can experiment.

Re: 5W resistor ?, marked 0.1ohm, 5W
On 06/06/2017 16:00, snipped-for-privacy@gmail.com wrote:
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Its in the speaker return path as a protector , annoyingly its not o/c  
but PbF tinpest? build up around its wire was causing the o/c.
In a Crate Flexwave 120/212 of 2008, with (tick) N222 "compliance" mark  
= PbF ? the solder does not react as PbF when admixing with SnPb .
I cracked the casing using too sharp and edge screwdriver , to force the  
issue, to prove solder joint failure, levering against the pcb.
Same ohm+zigzag logo as the other apparent 5W 0.47R emitter resistors

Re: 5W resistor ?, marked 0.1ohm, 5W
I scraped back some of that typical dusty grey coating of the "MO" and  
it is actually wire wound

Re: 5W resistor ?, marked 0.1ohm, 5W
N_Cook wrote:

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** The first pic shows a MO resistor, but there are WW examples that look near identical - as in the second pic.  

http://www.mojotone.com/Metal-Oxide-2W-10-OHM-Resistor-10-image.jpg

https://3.imimg.com/data3/CO/AE/MY-8302870/wire-wound-resistor-250x250.jpg




.....  Phil  


Re: 5W resistor ?, marked 0.1ohm, 5W
On 06/06/2017 18:16, N_Cook wrote:
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A genuine maker and seller of 0.1R, 2W w/w resitors would wind them with  
nichrome wire that could carry 4.5 amp current continuously but a  
genuine 5W version , he would use wire that would have to carry  7.1 amp  
continuously

Re: 5W resistor ?, marked 0.1ohm, 5W

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You can buy those low resistant resistors on ebay, rated at 100 watts,
for about $1 each. (from China). I bought a pair of 8 ohm ones, to use
for speaker load resistors, when I am testing power amps. They have an
aluminum housing with heat sink fins. It took about 3 weeks to get them
in the mail, but I was not in any hurry.

I know the OP said they are for speakers, but I do question their
purpose. Throw one of them 100W ones in there and it will last forever.


Re: 5W resistor ?, marked 0.1ohm, 5W
On 6/7/2017 1:38 PM, snipped-for-privacy@tubes.com wrote:
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Which is ABSOLUTELY NOT what Nigel needs.
He's replacing a 5 watt 0.1 ohm resistor in an amplifier.
The problem is that the original had 2 watt resistors inside a
5 watt body. I.e., cheap counterfeits.

Please try to keep up.


--  
Jeff-1.0
wa6fwi
We've slightly trimmed the long signature. Click to see the full one.
Re: 5W resistor ?, marked 0.1ohm, 5W
Foxs Mercantile wrote:

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** They're not counterfeits.  

Regular cement WW types have the same construction, a small ceramic tube with resistance wire wound on buried in cement and encased in a hard ceramic box.

The increased surface area provides the extra dissipation.


.....   Phil  

Re: 5W resistor ?, marked 0.1ohm, 5W




Quoted text here. Click to load it

You can buy those low resistant resistors on ebay, rated at 100 watts,
for about $1 each. (from China). I bought a pair of 8 ohm ones, to use
for speaker load resistors, when I am testing power amps. They have an
aluminum housing with heat sink fins. It took about 3 weeks to get them
in the mail, but I was not in any hurry.

I know the OP said they are for speakers, but I do question their
purpose. Throw one of them 100W ones in there and it will last forever.



************************************************************



If you are talking about this type of resistor, they are only rated at the  
stated Watts when mounted on a suitable heatsink.

If they are a dollar each from China, then you should probably derate them a  
further 75%.


http://www.farnell.com/datasheets/1498243.pdf?_ga=2.189825763.930466988.1496871749-1771980843.1483642398



Gareth.




Re: 5W resistor ?, marked 0.1ohm, 5W
N_Cook wrote:

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** No way it is for protection.  

The 0.1ohm is part of a positive feedback network to INCREASE the output impedance of the power amp.  

The low output impedance (or  high damping factor) of a SS power amp is not desirable in a guitar amp - so this trick fixes it.  

Makes the impedance more like 8ohms - so a DF of 1.  


.....  Phil  

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