Maker Pro
Maker Pro

Toroidal mains Tx inrush limiter - retrofit

N

N_Cook

Jan 1, 1970
0
Gareth Magennis said:
By the way,

What's the antithesis of Occam's razor?

dunno but talking to a philosopher last week for his take on occam's razor
,
he put me right in that it is a mistranslation of Occam's raison ...
I run science talks locally and he will be talking on the philosophy of
science, Nicomachean Ethics, Occam's whatever etc
series details
http://www.diverse.4mg.com/scicaf.htm
 
P

Phil Allison

Jan 1, 1970
0
"Nutcase fucking Kook"
dunno but talking to a philosopher last week for his take on occam's
razor
,
he put me right in that it is a mistranslation of Occam's raison ...

** Utter bullshit.

Kook is such a retarded fuckwit, god know how he remembers to shit.



...... Phil
 
M

Mike Tomlinson

Jan 1, 1970
0
s.com> said:
You must be quite the hit with the ladies.

Given that he seems to be obsessed with ass, I suspect he probably hangs
out in his local gay leather bar.
 
M

Mike Tomlinson

Jan 1, 1970
0
William Sommerwerck said:
Then what causes my bulk eraser to shut off when it overheats -- then come
back when it cools off?

That's a resettable *thermal* fuse, NOT a fuse designed for overcurrent
protection.
 
P

Phil Allison

Jan 1, 1970
0
"Mike Tomlinson"


** What a BORING know nothing, fuckwit bullshit artist.

The LESS you know about a topic - the MORE you feel compelled to talk
bollocks about it.

I call that sort of rampant narcissism: " pommy disease ".

Wot a shame it ain't fatal.



..... Phil
 
W

William Sommerwerck

Jan 1, 1970
0
"William Sommerwanker"

I love the fact I have a name that so lends itself to stupid wordplay.

** Have a fucking look.

I especially love the way you squirm when backed into a corner.
 
W

William Sommerwerck

Jan 1, 1970
0
Then what causes my bulk eraser to shut off when it overheats
That's a resettable *thermal* fuse, NOT a fuse designed for
overcurrent protection.

I had always thought that at least some polyfuses /were/ resettable.
Regardless, thanks for the answer.
 
P

Phil Allison

Jan 1, 1970
0
"William Sommerwanker is a Lying **** "
I love the fact I have a name that so lends itself to stupid wordplay.

** Have a fucking look !!!!!!!!!!!!!

You STINKING, AUTISTIC ARSEHOLE !!!
 
P

Phil Allison

Jan 1, 1970
0
"William Sommerwanker"
I had always thought that at least some polyfuses /were/ resettable.


** A " PolySwitch " is self resetting and so is a " Polyfuse".

Same basic device.

You fucking RETARD !!!!!!!




..... Phil
 
T

Tim Schwartz

Jan 1, 1970
0
This 300W amp blows correct T3.15A fuses every now and then at sw on. The
owner left in the last one so I can see it is just "tired" , neat break and
2 constituent parts of fuse wire remaining.

Any issues concerning putting in an ex pc SMPS 450W, 250V land mains inrush
thermistor, unknown specs, other than 14mm diameter, 4mm wide , 1mm diam
leads, 8R cold , 1R after 20 seconds touched by soldering iron barrel. Other
than poor physical integrity of the lead "welds" to the body (like disc
ceramic cap) - will mount on small high temp board and wire into the neutral
side of the wiring, with plenty of clear air space around.

Other than zero crossing Triac sub-cicuit to delay sw off, not creating
ferrite core residual magnetism, and delayed switching on also, any other
ways around this phenomenon other than bad practise uprating of the mains
fuse? Are polyswitches used in these circumstances , ie not purely "fuse"
action or generic name for devices specific for this purpose?

Nigel,

Also keep in mind as a possibility that the main filter caps are
getting tired, and a bit leaky, so that if the amp has not been switched
on for a week or 2, it might have abnormally high inrush current as the
caps charge/form back up.

Lastly, the older 'spring wire' fuses seemed more tolerant of the
inrush current compared to the modern chemically treated wire ones.
Maybe use an old style fuse, if you can find one.

It would be helpful if you would mention the make and model of the
product in your posts.

Regards,
Tim Schwartz
Bristol Electronics
 
P

Phil Allison

Jan 1, 1970
0
"Tim Schwartz"
Also keep in mind as a possibility that the main filter caps are getting
tired, and a bit leaky, so that if the amp has not been switched on for a
week or 2, it might have abnormally high inrush current as the caps
charge/form back up.

** This is rather fanciful thinking.

An inrush surge ( on a 240V supply) that will take out a T3.15 fuse has to
be in the order of 40 to 50 amps. Toroidal transformers in the range of 220
to 300 VA with rectifiers and filter cap banks will provide such surges
almost every time they are switched on.

Lastly, the older 'spring wire' fuses seemed more tolerant of the inrush
current

** Correct, but hard to find them in other than 3AG size and they are much
more expensive.
compared to the modern chemically treated wire ones.


** Where did you hear this one ??

The ones I use are said to be made from "plated wire" - meaning a thick
tin plating over copper. Some are coil shaped and some are not.

It would be helpful if you would mention the make and model of the product
in your posts.

** Bloody oath it would.

What a colossal ASS Kook is for regularly leaving that crucial info out.


..... Phil
 
G

Grant

Jan 1, 1970
0
Polyfuses (in the sense of the term I've always heard used) are
self-resetting, unless you hit 'em so hard that you damage them.

They aren't designed for use at mains voltages/currents, though... at
least, I haven't seen any that are.

Me neither, other thing with polyfuses is that there's approx 2:1 current
difference between trigger point and hold point. I have 16V and 30V poly-
fuses here, generally for 12V or 24V SLA battery powered gear.
The self-resetting thermal "fuses" that you'd find in a bulk eraser or
similar "not intended for a 100% duty cycle - let it cool down!"
device are (I think) of the bimetallic type, somewhat akin to what you
would find in a traditional wall thermostat.

Some are the same thing as used in clothes dryer for thermostat, 100% duty
cycle for years on end ;) Lower temperature for thermostat and a higher
temp one for overheat safety cutout.



Grant.
 
P

Phil Allison

Jan 1, 1970
0
"Grant"
Me neither, other thing with polyfuses is that there's approx 2:1 current
difference between trigger point and hold point.

** That is utterly misleading !!

There are no separate trigger and hold points with PolySwitches.

The makers specs allow for some device to device variation in the actual
current level that will trigger a RANGE of similar devices to change state
and go high resistance.

The max current that fails to trip all examples of a given type is called: "
I Hold ".

The minimum current that will trip all examples of a given type is called: "
I Trip".

" I Trip " is double " I Hold".

For any given device, the trip current is one number.

Once a device has tripped, the current needed to HOLD it in the new state is
a function of the applied voltage and is generally 5 to 20 times less than
the trip current.



..... Phil
 
N

N_Cook

Jan 1, 1970
0
This green thermistor limiter 10 deg C over ambient with no throughput and
20 deg C over with 0.4 amp mains with amp driving load.
 
M

Mike Tomlinson

Jan 1, 1970
0
N_Cook <[email protected]> said:
This green thermistor limiter 10 deg C over ambient with no throughput and
20 deg C over with 0.4 amp mains with amp driving load.

Bit warmer than I would be comfortable with.
 
P

Phil Allison

Jan 1, 1970
0
"Mike Tomlinson"
Nutcase Kook"
Bit warmer than I would be comfortable with.

** So neither of you has a clue how NTC surge limiters are meant to work ?



...... Phil
 
N

N_Cook

Jan 1, 1970
0
Mike Tomlinson said:
Bit warmer than I would be comfortable with.


Odd you say that. The next amp I looked at, this time mixer amp but also
300W and toroid Tx. Owner bought knowing 2 of the 8 channels were duff and
used as such for some years. He now needs all 8 ch .
Before he owned it , it must have been dropped and broke the awkward
size/shape mains switch. So someone spade jumpered the leads and covered
with heatshrink, leaving un-blanked off hole in chassis. Under his
heatshrink and touching the ordinary mains wire sleeving is an inrush
thermistor. Black , with 0.8mm leads, marked SG 130, 3.2R cold, 0.8R 20 sec
of soldering iron barrel. Presumably originally fixed to the sw and
unsupported other lead other than cable tie further down the cable loom.
Hopefully originally there was some woven glass sleeving over the thermistor

data for SG130 RTI Surge Guard, 0.07 ohms at 7 amps max , 2.5R at 25 deg C
27 joules rating for a 15 x 6.3 mm black (body radiator?) lump and .8mm
leads for anyone who can convert to temperature (not on the RTI datasheet)
 
Top