Re: Hmm!


"Phil Allison" <philallison@xxxxxxxxxx> wrote in message
news:67kk43F2pdepgU1@xxxxxxxxxxxxxxxxxxxxx

"Trevor Wilson"
"Phil Allison"

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**Depends on the fuse. I just measured half a dozen 0.25 Amp 3AG fuses.
They ranged from 12 Ohms up to 15 Ohms. COLD.


** That is an unbelievably high resistance value - not at all
consistent with a 250mA fuse.

**Nevertheless, it is correct.


** What is the brand of the fuses and where did you buy them ?

**UPDATE!

I checked a bunch of the fuses. The ones which measured high were 'Ralmar'
branded. I checked some branded (Littlefuse) ones and found them to be 5.3
Ohms. A couple of unbranded ones in the bottom of the drawer (probably WES
ones) were 5.5 Ohms. The Ralmar fuses have been placed where they belong (in
the trash). I also checked a Littlefuse M205 type at 4.7 Ohms.



No brand, 1/4 amp 3AG fuses I checked ranged from 3.5 to 4.5 ohms.

These values are at the upper limit for a 250mA rated, fast acting fuse.


These 20mm "T" or delay fuses from Bussman are speced at 0.66 ohms for a
250mA size:

http://www.farnell.com/datasheets/81115.pdf

The specs show that R rises to 1 ohm at rated current.


** The cold value is 0.66 ohm - not 12 or 15 ohms.

Your figures are completely non-typical.

**For Ralmar fuses, apparently not. For decent quality fuses - yep.

Trevor Wilson


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