Re: Hmm!
"Trevor Wilson"
"Phil Allison"
Your figures are completely non-typical.
**If I find some different fuses I will test them.
** There IS a manufacturing problem with your 250mA fuses !!!
I found that some of my stock of low current fuses gave absurdly high
resistance readings too - if tested with a DMM or Bobs ESR meter.
After testing at the rated current, with a current limited PSU, the fuse's
resistance value returned to normal.
Theory:
Low current fuses are made with resistance wire, not copper or tin wire as
with higher current types.
Where the wire ends are soldered to the fuse caps, a high resistance joint
can form.
Applying a few volts breaks down whatever corrosion is causing this
resistance.
DMMs etc do not apply enough voltage to have any curative effect.
...... Phil
.
Relevant Pages
- Re: Right. Own up.
... toughest ones in terms of power consumption to produce. ... the expensive thyristors that the fuses were there to protect). ... variable resistors, one per phase, which consist of a movable electrode ... The resistance is varied by moving ...
(alt.sysadmin.recovery) - Re: Low Volts High Current!
... >you also need some added largish capacitor to make up for the fact that it ... We have assumed tha Cbig has no resistance. ... When a bipolar transistor heats up, ... > They make special fuses for things like car starter motors. ...
(sci.electronics.design) - Re: Low Volts High Current!
... >you also need some added largish capacitor to make up for the fact that it ... We have assumed tha Cbig has no resistance. ... When a bipolar transistor heats up, ... > They make special fuses for things like car starter motors. ...
(sci.electronics.basics) - Re: blown output transistors
... multimeter also has a transistor check but it's pretty flaky especially ... hfe which was in the range of what the data sheet might lead one to expect. ... Fast fuses are very slow compared to what a tr can survive. ... You can make those out of a reel of resistance wire, ...
(sci.electronics.repair) - Re: House of Horrors
... > There's melting point as well as resistance to consider. ... > fuse copper would be much too thin mechanically so tin could be used. ... dropping a significant voltage. ... What is less obvious is that 'identically' rated fuses from different manufactures can have substantially different resistance, I remember testing fuses from several manufactures in order to find one with a very low resistance so as to minimise the effect on source impedance of a signal generator and not cause a significant drop in the output voltage. ...
(uk.tech.digital-tv) |
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