[Paul Dorman]

This was used for a guitar amp that was continually
blowing slow-blow fuses instantly upon turning the amp
on.

https://www.youtube.com/watch?v=k5oNQ1etN2c

In my case, the bulb would briefly light up, and then
fade out within about a second. I read this meant the
amp was normal, and didn't have a short to ground, and
when I plugged the amp into the wall normally, I was able
to trouble-shoot it normally.

But I would assume the bulb lighting up initially, is due
to the initial in-rush current, that charges up the electrolytic
filtering caps, on the outputs of the rectifiers?

Because the initial 1 second flash only happened with a
linear power supply guitar amp, and did not happen with
my switched-mode guitar amp. With the latter, the bulb
never glowed noticeably, even at turn-on.

[[email protected]]

Paul wrote:
============

But I would assume the bulb lighting up initially, is due
to the initial in-rush current, that charges up the electrolytic
filtering caps, on the outputs of the rectifiers?


** The largest part of the " inrush surge " is down to the iron transformer core *magnetising* and losing nearly all of its inductance at switch own.
Can take 20 cycles of AC power for the core to unmagnetise too.

SMPSs usually surge hard at a switch on too, yours must be an exception.


...... Phil

[Don Pearce[_3_]]

On Sun, 20 Dec 2020 16:44:56 -0700, Paul Dorman
wrote:

This was used for a guitar amp that was continually
blowing slow-blow fuses instantly upon turning the amp
on.

https://www.youtube.com/watch?v=k5oNQ1etN2c

In my case, the bulb would briefly light up, and then
fade out within about a second. I read this meant the
amp was normal, and didn't have a short to ground, and
when I plugged the amp into the wall normally, I was able
to trouble-shoot it normally.

But I would assume the bulb lighting up initially, is due
to the initial in-rush current, that charges up the electrolytic
filtering caps, on the outputs of the rectifiers?

Because the initial 1 second flash only happened with a
linear power supply guitar amp, and did not happen with
my switched-mode guitar amp. With the latter, the bulb
never glowed noticeably, even at turn-on.

You will find that the bulb has a rather finite lifetime.Instead use
the part designed for the job, a negative temperature coefficient
(NTC) thermistor. Any switched mode power supply is most likely to
already have one fitted, which is why your bulb seems to do nothing.

d

[[email protected]]

Don Pearce Pomy Bull**** Artist puked:

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


Because the initial 1 second flash only happened with a
linear power supply guitar amp, and did not happen with
my switched-mode guitar amp. With the latter, the bulb
never glowed noticeably, even at turn-on.

------------------------------------------------------------------------------
You will find that the bulb has a rather finite lifetime.


** ROTFLMAO - how ****ing ABSURD !!


Instead use the part designed for the job,

** How do you spell * misconstrue *" ????

The Don Pearce retard needs to know so he can look it up.....


a negative temperature coefficient
(NTC) thermistor. Any switched mode power supply is most likely to
already have one fitted, which is why your bulb seems to do nothing.

** Wot utter GARBAGE !!!!

Don the Nong has less that ZERO idea of what he is speaking about.


....... Phil

[Don Pearce[_3_]]

On Mon, 21 Dec 2020 03:06:38 -0800 (PST), "
wrote:

Don Pearce Pomy Bull**** Artist puked:

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


Because the initial 1 second flash only happened with a
linear power supply guitar amp, and did not happen with
my switched-mode guitar amp. With the latter, the bulb
never glowed noticeably, even at turn-on.

------------------------------------------------------------------------------
You will find that the bulb has a rather finite lifetime.


** ROTFLMAO - how ****ing ABSURD !!


Instead use the part designed for the job,

** How do you spell * misconstrue *" ????

The Don Pearce retard needs to know so he can look it up.....


a negative temperature coefficient
(NTC) thermistor. Any switched mode power supply is most likely to
already have one fitted, which is why your bulb seems to do nothing.

** Wot utter GARBAGE !!!!

Don the Nong has less that ZERO idea of what he is speaking about.


...... Phil


You are insulting a man who has designed switched mode power supplies,
and has included NTC thermistors for the purpose of limiting switch-on
inrush current. These thermistors are normally specified by customers
who have inrush current as part of their specification.

Have a read of an application note from TDK.

https://product.tdk.com/info/en/prod...c-limiter.html

d

[Don Pearce[_3_]]

On Mon, 21 Dec 2020 11:21:26 GMT, (Don Pearce) wrote:

On Mon, 21 Dec 2020 03:06:38 -0800 (PST), "
wrote:

Don Pearce Pomy Bull**** Artist puked:

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


Because the initial 1 second flash only happened with a
linear power supply guitar amp, and did not happen with
my switched-mode guitar amp. With the latter, the bulb
never glowed noticeably, even at turn-on.

------------------------------------------------------------------------------
You will find that the bulb has a rather finite lifetime.


** ROTFLMAO - how ****ing ABSURD !!


Instead use the part designed for the job,

** How do you spell * misconstrue *" ????

The Don Pearce retard needs to know so he can look it up.....


a negative temperature coefficient
(NTC) thermistor. Any switched mode power supply is most likely to
already have one fitted, which is why your bulb seems to do nothing.

** Wot utter GARBAGE !!!!

Don the Nong has less that ZERO idea of what he is speaking about.


...... Phil


You are insulting a man who has designed switched mode power supplies,
and has included NTC thermistors for the purpose of limiting switch-on
inrush current. These thermistors are normally specified by customers
who have inrush current as part of their specification.

Have a read of an application note from TDK.

https://product.tdk.com/info/en/prod...c-limiter.html

d

Or if you aren't into reading, try this

https://www.youtube.com/watch?v=U_0trB4ObwE

d

[[email protected]]

Don Pearce, Lying, Bull****ting pommy idiot spewed:

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

Because the initial 1 second flash only happened with a
linear power supply guitar amp, and did not happen with
my switched-mode guitar amp. With the latter, the bulb
never glowed noticeably, even at turn-on.

------------------------------------------------------------------------------
You will find that the bulb has a rather finite lifetime.


** ROTFLMAO - how ****ing ABSURD !!


** Suspect Don has realised his stupid blunder here.
Bit will never admit to it.
--------------------------------------------------------------------


a negative temperature coefficient
(NTC) thermistor. Any switched mode power supply is most likely to
already have one fitted, which is why your bulb seems to do nothing.

** Wot utter GARBAGE !!!!

Don the Nong has less that ZERO idea of what he is speaking about.

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


You are insulting a man who has designed switched mode power supplies,

** But clearly, not insulted him near enough to shut the idiot up.


and has included NTC thermistors for the purpose of limiting switch-on
inrush current.

** The geriatric fool has no clue at all.



...... Phil

[Don Pearce[_3_]]

On Mon, 21 Dec 2020 10:39:57 GMT, (Don Pearce) wrote:

On Sun, 20 Dec 2020 16:44:56 -0700, Paul Dorman
wrote:

This was used for a guitar amp that was continually
blowing slow-blow fuses instantly upon turning the amp
on.

https://www.youtube.com/watch?v=k5oNQ1etN2c

In my case, the bulb would briefly light up, and then
fade out within about a second. I read this meant the
amp was normal, and didn't have a short to ground, and
when I plugged the amp into the wall normally, I was able
to trouble-shoot it normally.

But I would assume the bulb lighting up initially, is due
to the initial in-rush current, that charges up the electrolytic
filtering caps, on the outputs of the rectifiers?

Because the initial 1 second flash only happened with a
linear power supply guitar amp, and did not happen with
my switched-mode guitar amp. With the latter, the bulb
never glowed noticeably, even at turn-on.

You will find that the bulb has a rather finite lifetime.Instead use
the part designed for the job, a negative temperature coefficient
(NTC) thermistor. Any switched mode power supply is most likely to
already have one fitted, which is why your bulb seems to do nothing.

d

I should add. The cold/hot resistance change is much greater in the
NTC thermistor, which means that while it does a much better job of
limiting the initial inrush current, its resistance once it reaches
its final state will be only a few tens of milliohms, so it becomes
essentially invisible to the circuit in operation.

This would be a typical choice

https://uk.farnell.com/ametherm/sl22...tor/dp/1703898

d

[Scott Dorsey]

In article ,
Paul Dorman wrote:
This was used for a guitar amp that was continually
blowing slow-blow fuses instantly upon turning the amp
on.

https://www.youtube.com/watch?v=k5oNQ1etN2c

In my case, the bulb would briefly light up, and then
fade out within about a second. I read this meant the
amp was normal, and didn't have a short to ground, and
when I plugged the amp into the wall normally, I was able
to trouble-shoot it normally.

But I would assume the bulb lighting up initially, is due
to the initial in-rush current, that charges up the electrolytic
filtering caps, on the outputs of the rectifiers?

No. This is a "power-on thump" which is caused by the coupling capacitors
charging up, not the power supply.

It's made much worse with amplifiers that run on a single supply rail, so
the output of the power amp stage is sitting halfway between the supply
rail and ground during normal operation. This means there is a huge
coupling capacitor from the output stage to the speaker and that has to
charge up. While it is charging up, the woofer coil will bottom out.

Well-designed amplifiers have a protection relay that cuts the speaker off
when there is any appreciable DC offset. It will sometimes take a little
time to stabilize because of the turn-on thump.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[[email protected]]

Scott Dorsey wrote:

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

But I would assume the bulb lighting up initially, is due
to the initial in-rush current, that charges up the electrolytic
filtering caps, on the outputs of the rectifiers?

No. This is a "power-on thump" which is caused by the coupling capacitors
charging up, not the power supply.


** The OP never mentioned any " thump" and is not talking about one.

It's made much worse with amplifiers that run on a single supply rail, so
the output of the power amp stage is sitting halfway between the supply
rail and ground during normal operation. This means there is a huge
coupling capacitor from the output stage to the speaker and that has to
charge up. While it is charging up, the woofer coil will bottom out.


** Nonsense, speaker output electros ( rarely seen in the last 30 years) do not do that, they charge slowly.

I = C.dv/dt

if C = 2000uF and the cap charges to 30V in 0.5 second, I = 120mA.

To " bottom out " a woofer a takes several amps.

Well-designed amplifiers have a protection relay that cuts the speaker off
when there is any appreciable DC offset. It will sometimes take a little
time to stabilize because of the turn-on thump.

** Direct coupled amps sometimes have such relays, a great many do not and don't need them.

In most cases, a simple muting FET between the pre and power stage does the job.


.......... Phil

[[email protected]]

Don Pearce cannot stop Bull****ting wrote:

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

I should add. The cold/hot resistance change is much greater in the
NTC thermistor, which means that while it does a much better job of
limiting the initial inrush current, its resistance once it reaches
its final state will be only a few tens of milliohms, so it becomes
essentially invisible to the circuit in operation.

This would be a typical choice

https://uk.farnell.com/ametherm/sl22...tor/dp/1703898

** Don just makes stuff up.

The presence or not of an NTC in an *amplifier" has no effect on the behavior of a "dim bulb"at switch on.

I deal with this stuff *every day* and Don does NOT !!!


....... Phil

[Scott Dorsey]

wrote:
Scott Dorsey wrote:

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

But I would assume the bulb lighting up initially, is due
to the initial in-rush current, that charges up the electrolytic
filtering caps, on the outputs of the rectifiers?

No. This is a "power-on thump" which is caused by the coupling capacitors
charging up, not the power supply.


** The OP never mentioned any " thump" and is not talking about one.

Yes, you are correct. From the original post, it seemed like he was using
a protection lamp on the speaker output (which is a common thing to do),
not on the AC line (which is also a fairly common thing for people to do
when they don't have a variac).
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Paul Dorman]

On 12/21/2020 3:04 PM, Scott Dorsey wrote:
wrote:
Scott Dorsey wrote:

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

But I would assume the bulb lighting up initially, is due
to the initial in-rush current, that charges up the electrolytic
filtering caps, on the outputs of the rectifiers?

No. This is a "power-on thump" which is caused by the coupling capacitors
charging up, not the power supply.


** The OP never mentioned any " thump" and is not talking about one.

Yes, you are correct. From the original post, it seemed like he was using
a protection lamp on the speaker output (which is a common thing to do),
not on the AC line (which is also a fairly common thing for people to do
when they don't have a variac).
--scott


If you watched the video I posted, you'd see the
schematic is a very simple light bulb in series with
the "Hot" side of the AC line:

https://www.antiqueradio.org/art/DimbulbSketch.jpg

Yes, these are typically used when you don't have
a variac.

But audio turn-on "thumps" do not last a full
second! I stand by my theory that the initial in-rush
of current is the charging up of the electrolytic
filtering caps, on the outputs of the rectifiers.

But apparently, you are correct that light bulbs
are sometimes used in series with speakers, to protect
them:

https://trueaudio.com/st_prot1.htm

[Paul Dorman]

On 12/21/2020 3:39 AM, Don Pearce wrote:
On Sun, 20 Dec 2020 16:44:56 -0700, Paul Dorman
wrote:

This was used for a guitar amp that was continually
blowing slow-blow fuses instantly upon turning the amp
on.

https://www.youtube.com/watch?v=k5oNQ1etN2c

In my case, the bulb would briefly light up, and then
fade out within about a second. I read this meant the
amp was normal, and didn't have a short to ground, and
when I plugged the amp into the wall normally, I was able
to trouble-shoot it normally.

But I would assume the bulb lighting up initially, is due
to the initial in-rush current, that charges up the electrolytic
filtering caps, on the outputs of the rectifiers?

Because the initial 1 second flash only happened with a
linear power supply guitar amp, and did not happen with
my switched-mode guitar amp. With the latter, the bulb
never glowed noticeably, even at turn-on.

You will find that the bulb has a rather finite lifetime.Instead use
the part designed for the job, a negative temperature coefficient
(NTC) thermistor. Any switched mode power supply is most likely to
already have one fitted, which is why your bulb seems to do nothing.


While a thermistor might also prevent a fuse from blowing out,
it doesn't give you a visual sign that there is a short-to-ground in
the circuit being tested.

The light bulb turns on when there is a short to ground.

[Paul Dorman]

On 12/21/2020 3:39 AM, Don Pearce wrote:
On Sun, 20 Dec 2020 16:44:56 -0700, Paul Dorman
wrote:

This was used for a guitar amp that was continually
blowing slow-blow fuses instantly upon turning the amp
on.

https://www.youtube.com/watch?v=k5oNQ1etN2c

In my case, the bulb would briefly light up, and then
fade out within about a second. I read this meant the
amp was normal, and didn't have a short to ground, and
when I plugged the amp into the wall normally, I was able
to trouble-shoot it normally.

But I would assume the bulb lighting up initially, is due
to the initial in-rush current, that charges up the electrolytic
filtering caps, on the outputs of the rectifiers?

Because the initial 1 second flash only happened with a
linear power supply guitar amp, and did not happen with
my switched-mode guitar amp. With the latter, the bulb
never glowed noticeably, even at turn-on.

You will find that the bulb has a rather finite lifetime.Instead use
the part designed for the job, a negative temperature coefficient
(NTC) thermistor. Any switched mode power supply is most likely to
already have one fitted, which is why your bulb seems to do nothing.


It's not clear to me that a thermistor would prevent a fuse from
blowing in a guitar amp, or any other circuit, that has a short
to ground. Because while the resistance may be high initially, while
the thermistor is cold, the resistance will go low as it heats up,
allowing the fuse to blow.

A thermistor also doesn't give you a visual indication that a
short-to-ground is in the circuit under test, as a light bulb does.

Remember a light bulb in series with the AC line, is mainly a
trouble-shooting tool.

[[email protected]]

Paul wrote:
===========

But audio turn-on "thumps" do not last a full
second! I stand by my theory that the initial in-rush
of current is the charging up of the electrolytic
filtering caps, on the outputs of the rectifiers.

** PSU electros normally charge fully in two cycles of AC power.
The presence of a 75 or 100W lamp in series makes that take longer.
With a tube radio, it is the heater current surge that takes a few seconds.
With large iron core transformers, they are the main culprit with single cycle surges up to 150amps.


But apparently, you are correct that light bulbs
are sometimes used in series with speakers, to protect
them:

https://trueaudio.com/st_prot1.htm

** LOL - it is never a supply voltage lamp that is used.

12 and 24V halogen bulbs *are* used but only rarely to protect a woofer or whole speaker .


...... Phil

[Paul Dorman]

On 12/20/2020 8:01 PM, wrote:
Paul wrote:
============

But I would assume the bulb lighting up initially, is due
to the initial in-rush current, that charges up the electrolytic
filtering caps, on the outputs of the rectifiers?


** The largest part of the " inrush surge " is down to the iron transformer core *magnetising* and losing nearly all of its inductance at switch own.
Can take 20 cycles of AC power for the core to unmagnetise too.

SMPSs usually surge hard at a switch on too, yours must be an exception.


The iron transformer is magnetizing every cycle, which
would be 60 times a second, for 60Hz AC.

If the secondary was open, and not connected to anything,
then the back EMF would be high enough, to prevent the light
bulb from turning on, due to the low current draw.

When the secondary is wired to the rectifiers, there is
now a load, and the large filtering caps need to be charged up,
which I believe is the reason the light bulb turns on briefly,
for about one second.

[[email protected]]

Paul wrote:
=============

It's not clear to me that a thermistor would prevent a fuse from
blowing in a guitar amp, or any other circuit, that has a short
to ground. Because while the resistance may be high initially, while
the thermistor is cold, the resistance will go low as it heats up,
allowing the fuse to blow.

** Under a short circuit condition , NTC thermistors *explode*
like a fire cracker spreading debris all over the place.

Remember a light bulb in series with the AC line, is mainly a
trouble-shooting tool.

** Of course, a very primitive one that works only sometimes.

Tube radios and tube amps are the main use.

May SS amps will refuse to work with a lamp in series.


..... Phil

[[email protected]]

Paul wrote:
============

** The largest part of the " inrush surge " is down to the iron transformer
core *magnetising* and losing nearly all of its inductance at switch own.

Can take 20 cycles of AC power for the core to unmagnetise too.

SMPSs usually surge hard at a switch on too, yours must be an exception.


The iron transformer is magnetizing every cycle, which
would be 60 times a second, for 60Hz AC.


** But not at *switch on * !!!!!!!!!

The phenomenon is called " inrush surge" and is a *whole subject* on its own.

This article from my colleague Rod Elliott may give you a hint.

https://sound-au.com/articles/inrush.htm


..... Phil

[Ralph Barone[_3_]]

wrote:
Paul wrote:
============

** The largest part of the " inrush surge " is down to the iron transformer
core *magnetising* and losing nearly all of its inductance at switch own.

Can take 20 cycles of AC power for the core to unmagnetise too.

SMPSs usually surge hard at a switch on too, yours must be an exception.


The iron transformer is magnetizing every cycle, which
would be 60 times a second, for 60Hz AC.


** But not at *switch on * !!!!!!!!!

The phenomenon is called " inrush surge" and is a *whole subject* on its own.

This article from my colleague Rod Elliott may give you a hint.

https://sound-au.com/articles/inrush.htm


.... Phil




Section 4 of your linked article talks about transformer inrush, which is a
definite concern for equipment with large power transformers. We had an
event a couple years ago when energizing some 500 MVA, 500 kV transformers
at the wrong point on wave resulted in a large outage and actual
destruction of some other equipment in the vicinity.

[Ralph Barone[_3_]]

wrote:
Scott Dorsey wrote:

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

But I would assume the bulb lighting up initially, is due
to the initial in-rush current, that charges up the electrolytic
filtering caps, on the outputs of the rectifiers?

No. This is a "power-on thump" which is caused by the coupling capacitors
charging up, not the power supply.


** The OP never mentioned any " thump" and is not talking about one.

It's made much worse with amplifiers that run on a single supply rail, so
the output of the power amp stage is sitting halfway between the supply
rail and ground during normal operation. This means there is a huge
coupling capacitor from the output stage to the speaker and that has to
charge up. While it is charging up, the woofer coil will bottom out.


** Nonsense, speaker output electros ( rarely seen in the last 30
years) do not do that, they charge slowly.

I = C.dv/dt

if C = 2000uF and the cap charges to 30V in 0.5 second, I = 120mA.

To " bottom out " a woofer a takes several amps.


Sure. But lets say that the power supply comes up to full voltage in 1/4
cycle, which is perhaps closer to the truth. 1/4 cycle is either 4.33 or 5
ms, depending on where you live. Punch in those numbers and you get dV/dt =
30/0.005 = 6000 V/sec and I = 6000 * 0.002 = 12 A. Thatll make your
woofer move.


Well-designed amplifiers have a protection relay that cuts the speaker off
when there is any appreciable DC offset. It will sometimes take a little
time to stabilize because of the turn-on thump.

** Direct coupled amps sometimes have such relays, a great many do not
and don't need them.

In most cases, a simple muting FET between the pre and power stage does the job.


......... Phil

[[email protected]]

Ralph Barone wrote:
=================

** Nonsense, speaker output electros ( rarely seen in the last 30
years) do not do that, they charge slowly.

I = C.dv/dt

if C = 2000uF and the cap charges to 30V in 0.5 second, I = 120mA.

To " bottom out " a woofer a takes several amps.

Sure. But lets say that the power supply comes up to full voltage in 1/4
cycle, which is perhaps closer to the truth.

** Irrelevant what the main PSU voltage does- and it is never a short as 5ms.
The mid point voltage of a single supply output stage rise *independantly*.

Like I posted, it typically takes a second or two.

..... Phil

[Paul Dorman]

On 12/21/2020 5:56 PM, wrote:
Paul wrote:
============

** The largest part of the " inrush surge " is down to the iron transformer
core *magnetising* and losing nearly all of its inductance at switch own.

Can take 20 cycles of AC power for the core to unmagnetise too.

SMPSs usually surge hard at a switch on too, yours must be an exception.


The iron transformer is magnetizing every cycle, which
would be 60 times a second, for 60Hz AC.


** But not at *switch on * !!!!!!!!!

The phenomenon is called " inrush surge" and is a *whole subject* on its own.

This article from my colleague Rod Elliott may give you a hint.

https://sound-au.com/articles/inrush.htm


From that article:

"Things become far more complicated when the secondary feeds a
rectifier, followed by a large bank of filter capacitors. Worst case
inrush current is still limited by the winding (and other) resistances,
but the capacitor bank appears to be a short circuit at the output of
the transformer. Depending on the size of the capacitors, the apparent
short circuit may last for some time. During this period, the
transformer will be grossly overloaded, but this is of little
consequence. Transformers can withstand huge overloads for a short
period with no damage, and they will normally last (almost) forever even
when subjected to such abuse many times a day."

[[email protected]]

Paul the Pedant wrote:

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


** The largest part of the " inrush surge " is down to the iron transformer
core *magnetising* and losing nearly all of its inductance at switch own.

Can take 20 cycles of AC power for the core to unmagnetise too.

SMPSs usually surge hard at a switch on too, yours must be an exception.


The iron transformer is magnetizing every cycle, which
would be 60 times a second, for 60Hz AC.


** But not at *switch on * !!!!!!!!!

The phenomenon is called " inrush surge" and is a *whole subject* on its own.

This article from my colleague Rod Elliott may give you a hint.

https://sound-au.com/articles/inrush.htm

From that article:

"Things become far more complicated when the secondary feeds a
rectifier, followed by a large bank of filter capacitors. Worst case
inrush current is still limited by the winding (and other) resistances,
but the capacitor bank appears to be a short circuit at the output of
the transformer. Depending on the size of the capacitors, the apparent
short circuit may last for some time. During this period, the
transformer will be grossly overloaded, but this is of little
consequence. Transformers can withstand huge overloads for a short
period with no damage, and they will normally last (almost) forever even
when subjected to such abuse many times a day."


** Please enjoy eating your carefully hand picked cherries.

And don't choke on the pips .....


..... Phil

[[email protected]]

Ralph Barone wrote:
=================

Section 4 of your linked article talks about transformer inrush, which is a
definite concern for equipment with large power transformers. We had an
event a couple years ago when energizing some 500 MVA, 500 kV transformers
at the wrong point on wave resulted in a large outage and actual
destruction of some other equipment in the vicinity.

** Be like bomb going off.

FYI:
Transformers a *lot smaller* can be a problem also.

1. Any toroidal power transformer of 800VA or more rating will regularly trip a household breaker at switch on.

2. A 1kVA conventioal job will do the same.

3. 40uF of AC rated film capacitors on the same switch will do it too ( for 240VAC power) .

4. Ditto for 2 or more colour CRT screens switched together.

Each of the above cause 150A peak surges that trip the magnetic part of the breaker.


...... Phil

[Paul Dorman]

On 12/21/2020 6:36 PM, wrote:
Paul the Pedant wrote:

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


** The largest part of the " inrush surge " is down to the iron transformer
core *magnetising* and losing nearly all of its inductance at switch own.

Can take 20 cycles of AC power for the core to unmagnetise too.

SMPSs usually surge hard at a switch on too, yours must be an exception.


The iron transformer is magnetizing every cycle, which
would be 60 times a second, for 60Hz AC.


** But not at *switch on * !!!!!!!!!

The phenomenon is called " inrush surge" and is a *whole subject* on its own.

This article from my colleague Rod Elliott may give you a hint.

https://sound-au.com/articles/inrush.htm

From that article:

"Things become far more complicated when the secondary feeds a
rectifier, followed by a large bank of filter capacitors. Worst case
inrush current is still limited by the winding (and other) resistances,
but the capacitor bank appears to be a short circuit at the output of
the transformer. Depending on the size of the capacitors, the apparent
short circuit may last for some time. During this period, the
transformer will be grossly overloaded, but this is of little
consequence. Transformers can withstand huge overloads for a short
period with no damage, and they will normally last (almost) forever even
when subjected to such abuse many times a day."


** Please enjoy eating your carefully hand picked cherries.

And don't choke on the pips .....


Well, these cherries support my argument that the initial
1 second of high current is due to the charging of the first
filter caps.

If you have cherries that can disprove my argument,
please present them.

[[email protected]]

Paul wrote:

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

If you have cherries that can disprove my argument,
please present them.


** Never cherry pic - it is ALWAYS a false argument.

My colleague's cite does not back you up one tiny bit. It is NOT about
the use of a dim bulb but operation at switch on with no limiting

I have already answered your fake idea.

Only tube amps do as you claim, it's due to tube heater current surge.
Tube rectifiers *never* allow filter cap surges.

FOAD.

...... Phil

[Paul Dorman]

On 12/21/2020 10:38 PM, wrote:
Paul wrote:

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

If you have cherries that can disprove my argument,
please present them.


** Never cherry pic - it is ALWAYS a false argument.

My colleague's cite does not back you up one tiny bit. It is NOT about
the use of a dim bulb but operation at switch on with no limiting

I have already answered your fake idea.

Only tube amps do as you claim, it's due to tube heater current surge.
Tube rectifiers *never* allow filter cap surges.

FOAD.

..... Phil


People resort to profanities when they don't have any real logical
argument!

You didn't even READ the link you posted! It fully supports my
argument! Thanks!

[[email protected]]

Paul the Prick wrote:

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


If you have cherries that can disprove my argument,
please present them.


** Never cherry pic - it is ALWAYS a false argument.

My colleague's cite does not back you up one tiny bit. It is NOT about
the use of a dim bulb but operation at switch on with no limiting

I have already answered your fake idea.

Only tube amps do as you claim, it's due to tube heater current surge.
Tube rectifiers *never* allow filter cap surges.

FOAD.

People resort to profanities when they don't have any real logical
argument!


** Like hell I don't.


You didn't even READ the link you posted! It fully supports my
argument! Thanks!

** You rotten bloody LIAR !!! It does nothing of the sort.

FYI:

Mr Elliott is a friend, he lives in Sydney as do I.
That article would never have been written without my urging and my input.
He and I discussed the facts it contains for many hours.

I was way ahead of him, but he then did his own testing and fully agreed.
Look over his site - many articles there are by me.


OTOH - you are nothing but a POS ****** with a very bad attitude.

I do hope you are 13 years old.

Cos otherwise you are comprehensively ****ed for the rest of you life


...... Phil

[Don Pearce[_3_]]

On Mon, 21 Dec 2020 03:55:24 -0800 (PST), "
wrote:

Don Pearce, Lying, Bull****ting pommy idiot spewed:

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

Because the initial 1 second flash only happened with a
linear power supply guitar amp, and did not happen with
my switched-mode guitar amp. With the latter, the bulb
never glowed noticeably, even at turn-on.

------------------------------------------------------------------------------
You will find that the bulb has a rather finite lifetime.


** ROTFLMAO - how ****ing ABSURD !!


** Suspect Don has realised his stupid blunder here.
Bit will never admit to it.
--------------------------------------------------------------------


a negative temperature coefficient
(NTC) thermistor. Any switched mode power supply is most likely to
already have one fitted, which is why your bulb seems to do nothing.

** Wot utter GARBAGE !!!!

Don the Nong has less that ZERO idea of what he is speaking about.

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


You are insulting a man who has designed switched mode power supplies,

** But clearly, not insulted him near enough to shut the idiot up.


and has included NTC thermistors for the purpose of limiting switch-on
inrush current.

** The geriatric fool has no clue at all.

Shame you didn't read your mate's article - which you claim to have
contributed to (an obvious lie). If you had you would have seen the
chapter about the use of NTC thermistors in limiting PSU inrush
current, and describing them as well-established. I presume according
to you he is also a geriatric fool with no clue.

Please take the meds, Phil.

d

[Paul Dorman]

On 12/22/2020 8:31 AM, Don Pearce wrote:
On Mon, 21 Dec 2020 03:55:24 -0800 (PST), "
wrote:

Don Pearce, Lying, Bull****ting pommy idiot spewed:

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

Because the initial 1 second flash only happened with a
linear power supply guitar amp, and did not happen with
my switched-mode guitar amp. With the latter, the bulb
never glowed noticeably, even at turn-on.

------------------------------------------------------------------------------
You will find that the bulb has a rather finite lifetime.


** ROTFLMAO - how ****ing ABSURD !!


** Suspect Don has realised his stupid blunder here.
Bit will never admit to it.
--------------------------------------------------------------------


a negative temperature coefficient
(NTC) thermistor. Any switched mode power supply is most likely to
already have one fitted, which is why your bulb seems to do nothing.

** Wot utter GARBAGE !!!!

Don the Nong has less that ZERO idea of what he is speaking about.

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


You are insulting a man who has designed switched mode power supplies,

** But clearly, not insulted him near enough to shut the idiot up.


and has included NTC thermistors for the purpose of limiting switch-on
inrush current.

** The geriatric fool has no clue at all.

Shame you didn't read your mate's article - which you claim to have
contributed to (an obvious lie). If you had you would have seen the
chapter about the use of NTC thermistors in limiting PSU inrush
current, and describing them as well-established. I presume according
to you he is also a geriatric fool with no clue.

Please take the meds, Phil.


Agreed, this Troll is a serious liar!

[[email protected]]

Don Pearce, Lying, Bull****ting pommy idiot spewed:
---------------------------------------------------------------------------------


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

Because the initial 1 second flash only happened with a
linear power supply guitar amp, and did not happen with
my switched-mode guitar amp. With the latter, the bulb
never glowed noticeably, even at turn-on.

------------------------------------------------------------------------------
You will find that the bulb has a rather finite lifetime.


** ROTFLMAO - how ****ing ABSURD !!


** Suspect Don has realised his stupid blunder here.
Bit will never admit to it.
--------------------------------------------------------------------


a negative temperature coefficient
(NTC) thermistor. Any switched mode power supply is most likely to
already have one fitted, which is why your bulb seems to do nothing.

** Wot utter GARBAGE !!!!

Don the Nong has less that ZERO idea of what he is speaking about.

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


You are insulting a man who has designed switched mode power supplies,

** But clearly, not insulted him near enough to shut the idiot up.


and has included NTC thermistors for the purpose of limiting switch-on
inrush current.

** The geriatric fool has no clue at all.

Shame you didn't read your mate's article - which you claim to have
contributed to (an obvious lie).

** The obvious leis her is you Don.


If you had you would have seen the
chapter about the use of NTC thermistors in limiting PSU inrush
current, and describing them as well-established. I presume according
to you he is also a geriatric fool with no clue.

** My god you are an utter ****ing ass.

I must have 25 different NTCs in my parts bins and use them as needed for surge current suppression.
I know exactly what they do and do not do.

You know neither.


....... Phil

[[email protected]]

Paul the Trolling ****head wrote:

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

Agreed, this Troll is a serious liar!


** ROTFL - wot absurd hypocrisy.

You are comprehensively ****ed in the head. .


...... Phil

[geoff]

On 22/12/2020 1:49 pm, wrote:
Paul wrote:
=============

It's not clear to me that a thermistor would prevent a fuse from
blowing in a guitar amp, or any other circuit, that has a short
to ground. Because while the resistance may be high initially, while
the thermistor is cold, the resistance will go low as it heats up,
allowing the fuse to blow.

** Under a short circuit condition , NTC thermistors *explode*
like a fire cracker spreading debris all over the place.

Remember a light bulb in series with the AC line, is mainly a
trouble-shooting tool.

** Of course, a very primitive one that works only sometimes.

Tube radios and tube amps are the main use.

May SS amps will refuse to work with a lamp in series.


.... Phil


I think the point of the OP was that if a short on the input side of
things, the lamp would come on, and stay on. Nothing to do with a flash
of inrush current. A totally different cup of soup, and not really of
very much relevance to many real-life situations.

Of more relevance is my 240v lamp with 2 test probes that I use to
discharge valve-amp PSUs before diving in. Works well, until the lamp
turns out to be have a broken filament. Screwdriver in my other hand
stuck in the wall 3 metres behind me, and my forefinger was numb for
several days.

geoff