Fuses, Am I That Stupid ?

[Jeff Urban]

Well maybe I am, but why can't I buy a bunch of fuses ? I want a bunch of 3AG, ranging from 1 to 15 amps, maybe five each. I go searching on Digikey n shit, nothing. But then I see in Google results there they are. Well for one, I ain't falling for that anymore and two, if I can't find it on you selector guide I think I might want to just get them elsewhere.

You know, I got about the best transistors here that will work in anything, even MOSFETs. I got the good replacements for the small signal stuff, I got both P and N channel real JFETs.

But now fuses are going to hold me up ? this is ridiculous.

The easiest way probably is NTE, but they cost three times what they should.

Maybe I just don't give a shit and pay them. I am near the point of just jumping them out and telling the customer "If it catches fire take it outside".

Sure, I could go to the auto parts store, and then for five fuses of different values it is five bucks. If I need two of the same value it is ten bucks. so I want like ten different values and thy only got five, but a set of five each will only run me $25. And I will use up one or two values and have to buy all that again to replenish my stock.

I don't know about you, but that does not seem like a really sound business practice to me.

They probably don't even have 1 amp in there. That is important. First of all 1 amp is never going to cause a hazard if you use it for a 750mA or whatever. Fuses rated that low are to detect certain faults. It could be four times the rating and not be a threat.

Still you need fuses. Why is it so fucking hard to get them ?

Maybe tomorrow I just get on the phone. Damn I hate the phone.

[Trevor Wilson]

**Try here:

https://au.mouser.com/Circuit-Protection/Fuses/Cartridge-Fuses/_/N-ba8h0

Scroll down under 'Series' for 3AG.

There's about a billion of them.

Or here:

https://www.digikey.com/products/en/circuit-protection/fuses/139?k=fuse

Scroll down under 'Series' for 3AG.

Another billion or so.

I've never experienced a problem purchasing fuses. Unless they happen to
be those fancy schmancy ones, like those in my Fluke multimeter (HRC type).

--
Trevor Wilson
www.rageaudio.com.au

--
This email has been checked for viruses by Avast antivirus software.
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[Fox's Mercantile]

On 8/18/20 4:26 AM, Jeff Urban wrote:
> Well maybe I am, but why can't I buy a bunch of fuses ?

And you wonder why I "pick" on you.

--
"I am a river to my people."
Jeff-1.0
WA6FWi
http:foxsmercantile.com

[Pimpom]

You don't seem to be too particular about the fusing
characteristics and just need some that blow with gross
overcurrent. Have you considered AliExpress? Ordinary glass fuses
are of the order of a US$ for 20 pcs plus a nominal shipping
charge. That is, if you can tolerate long transit times.

My location has always made it well-nigh impossible to be finicky
about the quality of common passive parts like fuses, resistors
and the like. I get what I can where I can and I've never had any
major problem with them.

[Tim Schwartz]

Good morning,

At Mouser or Digikey try searching for "Fuse kits" or "Fuse
assortments". For example, Digikey offers this:

https://www.digikey.com/product-detail/en/littelfuse-inc/312P-KIT/312P-KIT-ND/965783

140 fuses for around $94, in a box. They have a bunch of different
ones, so have a look. Personally, $1 per fuse or less of a brand I
trust is not a bad deal. If you are hoping for 10 cents per fuse,
you'll be out of luck.

Cheap fuses aren't worth it. I remember one supplier who was trying to
get us to buy some brand "X" fuses at a shop I was working at. He gave
us a box of 4 amp fast blow as a sample. When we tested them, we found
that at 8 amps of current, they glowed like a light bulb for many
minutes, where they should have blown within 5 seconds. We tossed them
out. This was 30 years ago.

I also had a friend in a car club that ordered a (glass) fuse
assortment from an eBay vendor. He then called me that he was having
problems with all sorts of things no working. It was because the fuses
did not conduct electricity. I put together an assortment of Littlefuse
or Buss fuses for his car.

I guess I'd rather have fuses that don't conduct electricity than ones
that fail to blow, as ones that don't conduct cause less smoke.

Regards,
Tim

[peterw...@gmail.com]

Seconding every word from Tim. Littlefuse or Bussman - that is about all I will use - if one considers that I would prefer not to have a $1,000 device fail to protect a $1.25 fuse, it makes more sense.
a) Tractor Supply sells assortments from Littlefuse - Over the counter.
b) Ferguson sells assortments from Bussman - OTC.
c) Mouser and Digikey sell all sorts of assortments from both - cheaper. Including mix-and-match.
d) My local electrical supply house sells onsies-twosies as well as assortments from both, Not cheap.

Would not call the OP stupid as much as bone-lazy.

Peter Wieck
Melrose Park, PA

[Fox's Mercantile]

On 8/18/20 11:05 AM, pf...@aol.com wrote:
> Would not call the OP stupid as much as bone-lazy.

The terms are interchangeable.

[peterw...@gmail.com]

> > Would not call the OP stupid as much as bone-lazy.
> The terms are interchangeable.

Not so much. "Stupid" is a special sort of disease and entirely incurable. On the other hand it is remarkable what a cattle-prod will do for congenital laziness.

[Ralph Mowery]

In article <9b557ad3-8ea6-4440...@googlegroups.com>,
peterw...@gmail.com says...

>
> > > Would not call the OP stupid as much as bone-lazy.
> > The terms are interchangeable.
>
> Not so much. "Stupid" is a special sort of disease and entirely incurable. On the other hand it is remarkable what a cattle-prod will do for congenital laziness.
>
>
>

Right, you can not cure stupid.

There is another group that seems stupid, but sometimes they are not
really stupid, just uneducated. I feel that I sometimes fall into that
group. Don't know, but trying to learn.

Sometimes with the right motivation you can moviate the lazy. Like
where I worked. It was almost impossiable to fire someone if they just
showed up every day. There was one lazy person and his boss made the
coment that as he could not fire that person, so he promoted the fat
lazy sob to a supervisor job. The company could get rid of bad
supervisors very easy. That motivated the person and he made a very
good and well liked supervisor.

[Michael_A_Terrell]

Jeff Urban wrote:
> Well maybe I am, but why can't I buy a bunch of fuses ? I want a bunch of 3AG, ranging from 1 to 15 amps, maybe five each. I go searching on Digikey n shit, nothing. But then I see in Google results there they are. Well for one, I ain't falling for that anymore and two, if I can't find it on you selector guide I think I might want to just get them elsewhere.

<https://www.digikey.com/products/en/circuit-protection/fuses/139?k=fuse>
lists both 3AG and AGCas you scrll down the list of series.

The link to 3AG (Bussman) is:

<https://www.digikey.com/products/en/circuit-protection/fuses/139?k=fuse&k=&pkeyword=fuse&sv=0&s=15468&sf=0&FV=-8%7C139&quantity=&ColumnSort=0&page=1&pageSize=250>

The link to AGC (Littlefuse)is:

<https://www.digikey.com/products/en/circuit-protection/fuses/139?k=fuse&k=&pkeyword=fuse&sv=0&s=15368&sf=0&FV=-8%7C139&quantity=&ColumnSort=0&page=1&pageSize=250>

--
Never piss off an Engineer!

They don't get mad.

They don't get even.

They go for over unity! ;-)

[Phil Allison]

Tim Schwartz wrote:

--------------------

>
>
> Cheap fuses aren't worth it. I remember one supplier who was trying to
> get us to buy some brand "X" fuses at a shop I was working at. He gave
> us a box of 4 amp fast blow as a sample. When we tested them, we found
> that at 8 amps of current, they glowed like a light bulb for many
> minutes, where they should have blown within 5 seconds. We tossed them
> out. This was 30 years ago.
>
> I also had a friend in a car club that ordered a (glass) fuse
> assortment from an eBay vendor. He then called me that he was having
> problems with all sorts of things no working. It was because the fuses
> did not conduct electricity.
>

** Pre-loved fuses?

Was given a Phase Linear 400 amp to repair once as it kept blowing DC rail fuses - but there turned out to be nothing wrong with the amp.

The DJ who owned the thing had bought a pack of 5A fuses from Tandy ( aka Radio Shack). Though clearly labelled on the pack and the fuse itself, they were not 5A. I tested one and it failed quickly at 2A.

IME no-brand fuses can fail prematurely or not at all !!

I came across a type of 3AG slo-blo that could NOT not tolerate an inrush surge. See third example from the left here:

https://www.mojotone.com/amp-parts/Fuses_1/Littelfuse-Slow-Blow-3AG-7-AMP

The fine wire is the fuse element and slowly heats the solder pot allowing the spring to pull the heavy wire out. However it will easily fail under inrush. This leaves the spring and heavy wire conducting currents up to 45A while glowing bright red and melting the fuse holder.

So "slo-blo" and anti-surge fuses are NOT the same thing.


.... Phil

[Pimpom]

I'm surprised at the accounts of fuses performing not just
outside spec but far outside it, especially in developed
countries. Like ones glowing for several minutes at twice the
rated current.

I use what I can get here and the 3-5 cent (US) fast-blow fuses I
normally stock are often crudely constructed. But they behave as
expected in the few tests I've done as well as in practical
products. They take several seconds to blow at the rated current
and quickly at 2x.

In a pinch, I've used copper wire as fuses, e.g. 41 SWG
(0.0044"/0.11mm) for 3A, 36SWG (0.0076"/0.19mm) for 7A, etc. They
also behave as expected.

[legg]

[legg]

On Tue, 18 Aug 2020 02:26:12 -0700 (PDT), Jeff Urban
<jurb...@gmail.com> wrote:

3AG is a series of glass bodied low voltage fuses.
(Automotive Glass)

You should replace fuses with the same type and
rating as was originally used.

Most fuses have enough information marked into
their end caps to identify their type and rating.

Keeping spares of type and rating that are used in
your equipment, or are commonly required in repairs
makes sense. There's no rush in obtaining them.

Getting the correct fuse, that you don't have, fast,
is worth the $8 shipping from Digikey, even for just
one.

Kits are just space wasters.

RL

[peterw...@gmail.com]

Any fuse used in line-voltage equipment should be rated at/above that line-voltage. I use nothing but 250VAC rated fuses, with the exception of what goes into low-voltage equipment which will be rated to the specific need and use.

Again, I am not of the persuasion that a $1,000 device should fail in order to protect a $0.25 fuse. Or, even a $3.00 fuse.

[Phil Allison]

Pimpom wrote:

==============

>
>
> I use what I can get here and the 3-5 cent (US) fast-blow fuses I
> normally stock are often crudely constructed. But they behave as
> expected in the few tests I've done as well as in practical
> products. They take several seconds to blow at the rated current
> and quickly at 2x.
>

** No fuse should blow at the rated current.

Cos the Amp rating is for the max holding value.

Slow acting ( ie T for trage ) types open at current levels not much above their rating, given enough time.


..... Phil

[Ralph Mowery]

In article <81e44a05-a0d9-4d88...@googlegroups.com>,
peterw...@gmail.com says...

>
> Again, I am not of the persuasion that a $1,000 device should fail in order to protect a $0.25 fuse. Or, even a $3.00 fuse.
>
>
>

The $ 1000 device has already failed when the fuse blows. The fuse is
really to protect the wiring going to the device. A fuse may prevent
major damage to the devise it is wired to. Such as in a power supply
part of the device a capacitor may short and the fuse may protect the
power transformer.

The common mistake about fuses is that it is to protect the device, but
it is really they are to protect the wiring and the power supply that is
feedig the device.

Without a fuse, the wires could get hot enough to cause a fire.

[peterw...@gmail.com]

> The common mistake about fuses is that it is to protect the device, but
> it is really they are to protect the wiring and the power supply that is
> feedig the device.
>
> Without a fuse, the wires could get hot enough to cause a fire.

A conventionally designed fuse, agreed, is to protect real-estate, not the device. However, a properly designed fuse will do at least a reasonable job of protecting a device against catastrophic failure. A well-matched dual-element fuse can be very closely match to the operating current of a device such that it can accept turn-on surges, but will blow if that operating current is exceed more than momentarily.

Not perfect. Far better than nothing. Most especially as it applies to tube audio equipment, and some motorized equipment.

[et...@whidbey.com]

My CNC machines have fuses in the servo motor drives that will blow if
the drive is overloaded long enough, such as in a crash. These fuses
protect the drives. I have replaced them several times. A couple
machines I used to have used repairable fuses. They had a flag held
down by some fuse wire. When the fuse blew the flag would show in a
window, so you would know which fuse to repair. Over the years I
replaced fuse wires many times.
Eric

---

[jurb...@gmail.com]

Google fucked this all up, up sorry to say goodbye.

[Phil Allison]

Ralph Mowery wrote:

==================

> >
>
> The $ 1000 device has already failed when the fuse blows. The fuse is
> really to protect the wiring going to the device. A fuse may prevent
> major damage to the devise it is wired to. Such as in a power supply
> part of the device a capacitor may short and the fuse may protect the
> power transformer.
>
> The common mistake about fuses is that it is to protect the device, but
> it is really they are to protect the wiring and the power supply that is
> feedig the device.
>
> Without a fuse, the wires could get hot enough to cause a fire.
>

** Supply line fuses limit damage to the following circuitry - particularly steel core transformers and other heat sensitive parts. Internal supply wiring should be and normally IS adequate to trip external breakers without burning up.

That makers specify a correct supply fuse to fit tells you it is not just for cable protection. However, the biggest mistake is to think user replaceable fuses actually protect anything.



..... Phil

[Pimpom]

I stand corrected. I just looked up some current datasheets and
it's hours at 100% and several secs at 200%. I haven't updated
myself and was thinking of some mfr's data and my own test from
long ago which were around 30 secs at 100% and 1 sec at 200%.

[Michael_A_Terrell]

legg wrote:
> On Tue, 18 Aug 2020 02:26:12 -0700 (PDT), Jeff Urban
> <jurb...@gmail.com> wrote:
>
> 3AG is a series of glass bodied low voltage fuses.
> (Automotive Glass)

Automotive fuses were SFE, until they switched to those plastic,
plug in type. They were rated for 32VDC maximum, and they got longer as
the current rating went up, to prevent you from putting in a much larger
fuse. Our shop used to stock over 250 series and values of fuses,
including the Belfuse chemical fuses.

[ohg...@gmail.com]

On Thursday, August 20, 2020 at 3:27:13 AM UTC-4, terrell....@gmail.com wrote:
> legg wrote:
> > On Tue, 18 Aug 2020 02:26:12 -0700 (PDT), Jeff Urban
> > <jurb...@gmail.com> wrote:
> >
> > 3AG is a series of glass bodied low voltage fuses.
> > (Automotive Glass)
> Automotive fuses were SFE, until they switched to those plastic,
> plug in type. They were rated for 32VDC maximum, and they got longer as
> the current rating went up, to prevent you from putting in a much larger
> fuse. Our shop used to stock over 250 series and values of fuses,
> including the Belfuse chemical fuses.
> --
>

Uh oh! You did *not* call them "chemical" fuses!!! Standby...

[Michael_A_Terrell]

That's what they are. The fuse element is coated with a chemical
that burns as soon as it reaches its critical temperature to ensure that
it opens quickly. They were use in the cathodes of Horizontal output
tubes, and some solid state circuits. They are very fast opening fuses,
and similar to the 7200V fuses used by utilities, except they use
gunpowder to quench the plasma. Both methods can run right below their
critical temperature without opening. Once any part of the element
reaches critical temperature, it opens. No sagging fuse elements that
change their fusing current from running too hot without opening. I've
seen some AGC fuses where it had melted, and drooped to the glass
without opening.

[tabb...@gmail.com]

There are fuses that pop at 100% rating, but the great majority of types carry 100% indefinitely.


NT

[ohg...@gmail.com]

We all know the Belfuse fuses were chemical fuses except for just *one* group contributor who is *never* wrong and said they aren't chemical fuses...

[Michael_A_Terrell]

What he doesn't know would fill entire libraries. I'll bet that he's
never heard of a Klystrode, either. They replaced Klystrons in high
power TV transmitters, but they wer more efficient so the station's
power bill was lower. the 5MW UHF site that I maintaining had a $45,000
per month electric bill. It would have been about 15 to 20% lower if it
used Klystrodes.