Close, Würzer. I have uncovered evidence that my father actually made the change even though the umlaut was already not allowed at the immigration of my grandparents.
Why not measure them? Bob Cordell did measure fuse distortion for his book.
See page 269.
I have measured them. This was in reference to the earlier post about beeswax filled fuses. There are bigger differences between brands than equal ratings in different body sizes. 1/2 amp is the fuse size with the most significant change in resistance per current ratting.
A fast blow fuse rated at ½ amp started off with a resistance of 1.24 ohms at .025A and increased to 1.93 ohms at .5 amps. That was the worst one I measured. (Off Brand.) Turns out the data is actually in the manufacturer's data sheets.
http://www.cooperindustries.com/con...uct-datasheets/Bus_Elx_DS_2000_ABC_Series.pdf
http://www.cooperindustries.com/con...sheets-a/Bus_Ele_DS_2015_GDB_GDB-V_Series.pdf
Note they give cold resistance and voltage drop at rated current. The 20mm fuses being shorter have a bit less voltage drop! So a prize goes to whoever can find a report of fuse testing by ear that identified that.
http://www.cooperindustries.com/con...uct-datasheets/Bus_Elx_DS_2000_ABC_Series.pdf
http://www.cooperindustries.com/con...sheets-a/Bus_Ele_DS_2015_GDB_GDB-V_Series.pdf
Note they give cold resistance and voltage drop at rated current. The 20mm fuses being shorter have a bit less voltage drop! So a prize goes to whoever can find a report of fuse testing by ear that identified that.
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Fuses? Fuses are for wimps, not Audiophiles....
We used to routinely, way back in the day, replace power fuses with offcuts from metal variable resistor shafts. Perfect fit, never blows... moves the problem upstream!
Mind you, that was when it was considered fun to plumb a load of big electrolytics into the power points on the engineering workbench to wake up the guy who was in first and flipped the isolator for the lab to on! Bang bang bang!!
Same here but we used to wrap a few turns of solder around power plugs and put them back in.
Or try to interrupt high voltage d.c.
In 1972 I was playing reeds in the backup band for a Japanese singer, on tour of about eight cities in about ten days. The band's guitar player, the still-active fine musician Craig T. Fall, with whom I've recently reconnected, plugged his Fender amp into an innocent-looking mains outlet. This was in a large hall in Chicago.
It turned out that to suppress acoustical hum from the stand lights, tubular incandescents, the outlets supplied d.c. Of course the amplifier didn't work, and in fairly short order (as people were beginning to file in and take their seats) we smelled the telltale odor of a burning power transformer. Inspection revealed that the cartridge fuse had failed shorted, with metallic vapor condensing on the inside of the glass envelope and maintaining quite enough conductivity to smoke the transformer. Ouch! At least no one shouted Fire!
No guitar parts that night!
And the data sheets make clear the DC voltage rating is lower than the AC voltage rating! Nice to have confirmation
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I would think AC resistance to be more important, no?
What is the resistance during AC excitation? Hook it up to the output of an amp, and sweep it into a resistive load, run the AP on it.
Now THAT would be really cool. As well, comparison of slow blow vs fast w/r to time constants.
John
Done that. Results as expected for any resistor with high tempco.
But as Demian mentioned if your power supply can't take a joke what do you think the AC mains variations will do to it.
Both are harmonics of 60 Hz, it's easy enough to actually plot the impedance of the capacitor vs frequency without all the potentially confounding data.
Once the first FFT shows there is a problem. I am stealing a page from Mark J and driving the capacitor bank with a square wave through a 10nF capacitor and then trying RC networks to damp the resulting ringing.
Clearly shows that just paralleling big uns and little uns can make things worse.
Please don't forget to include the part where you use linear systems theory to derive equations that tell you "if I increase X then Y should decrease" and "if I decrease J then K should get much worse" ? It was an essential piece of the work I did.
One nice feature of the application domain I chose is: hand analysis is tractable. Simulation is possible. Lab results can be confirmed two different ways. Does your study of fuses share these pleasant properties?
MarkJ
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