I'm looking for the wall wart for an exercise bike in my bin of such
things.
It needs 9v 0.5A and i've found one that's 9.6v 0.6A which (accepting
there's no danger of ever finding the original) is closer than I
expected to get.
But I have a 12v 1A with a longer cable, past experience tells me there
will be no bother using that but is it a problem? And if not when is it
likely to become one?

And why do similar rated ones differ so much in bulk? Is this just a
build quality issue?

On 29/01/2019 16:47, R D S wrote:
I'm looking for the wall wart for an exercise bike in my bin of such
things.
It needs 9v 0.5A and i've found one that's 9.6v 0.6A which (accepting
there's no danger of ever finding the original) is closer than I
expected to get.
But I have a 12v 1A with a longer cable, past experience tells me there
will be no bother using that but is it a problem? And if not when is it
likely to become one?

Depends on whether the bike has any regulation on its input. It probably
does (assuming this is just an electronic readout of speed / distance
etc). The 9.6V one would be the better bet.

And why do similar rated ones differ so much in bulk? Is this just a
build quality issue?

The main difference will usually be a light weight switch mode design vs
a older style linear supply. The older ones will have much heavier
transformers.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

In article ,
R D S wrote:
And why do similar rated ones differ so much in bulk? Is this just a
build quality issue?

Older ones will have a transformer. Newer ones a SMPS - smaller and
lighter.

--
*See no evil, Hear no evil, Date no evil.

Dave Plowman London SW
To e-mail, change noise into sound.

On 29/01/2019 16:47, R D S wrote:
I'm looking for the wall wart for an exercise bike in my bin of such
things.
It needs 9v 0.5A and i've found one that's 9.6v 0.6A which (accepting
there's no danger of ever finding the original) is closer than I
expected to get.
But I have a 12v 1A with a longer cable, past experience tells me there
will be no bother using that but is it a problem? And if not when is it
likely to become one?

Just before the smoke.

Open it up. If the PCB copper traces wind up *only* at a 7805 regulator
than it shouldn't be a real problem, except probably a little more heat
- perhaps arrange ventilation or a bigger regulator heatsink. If they go
elsewhere, than bets are off - it may be running analogue circuitry, I
guess amplifiers / comparators and the like for this kind of application.

And why do similar rated ones differ so much in bulk? Is this just a
build quality issue?

Some "linear" use large transformers run at 50Hz, some "SMPS" use
smaller transformers run at 20kHz upwards with more electronics to go
bang.

--
Adrian C

John Rumm brought next idea :
Depends on whether the bike has any regulation on its input. It probably does
(assuming this is just an electronic readout of speed / distance etc). The
9.6V one would be the better bet.

There has been no mention of ac or dc output/input?

If you want to lose 0.6 - 0.7V put a diode in series on the positive output.

Richard

I'm assuming all of these are analogue ones, ie Heavy to pick up. If so then
probably the 12v one is using a better specified transformer. Be careful
though, as unless you are sure the device is able to accept raw DC you
might have issues with ripple.
Also I had two here for an old dab radio, one gets so hot it has partly
melted the case the other runs cool. The only reason for the difference as
far as I can see is that the transformer in the hot one is crap.

Brian

--
----- --
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"R D S" wrote in message
...
I'm looking for the wall wart for an exercise bike in my bin of such
things.
It needs 9v 0.5A and i've found one that's 9.6v 0.6A which (accepting
there's no danger of ever finding the original) is closer than I expected
to get.
But I have a 12v 1A with a longer cable, past experience tells me there
will be no bother using that but is it a problem? And if not when is it
likely to become one?

And why do similar rated ones differ so much in bulk? Is this just a build
quality issue?

"R D S" wrote in message
...
I'm looking for the wall wart for an exercise bike in my bin of such
things.
It needs 9v 0.5A and i've found one that's 9.6v 0.6A which (accepting
there's no danger of ever finding the original) is closer than I expected
to get.

But I have a 12v 1A with a longer cable, past experience tells me there
will be no bother using that but is it a problem?

Unlikely to be a problem but its possible that a badly
designed exercise bike might have a problem with it.

And if not when is it likely to become one?

Again, impossible to say. It depends on what
the internal voltage regulator has heatsink wise.

And why do similar rated ones differ so much in bulk?

The ones with iron cored transformers are much
bigger than modern switch mode wall warts.

Is this just a build quality issue?

Nope.

On Tuesday, 29 January 2019 17:09:04 UTC, Dave Plowman (News) wrote:
In article ,
R D S wrote:
And why do similar rated ones differ so much in bulk? Is this just a
build quality issue?

Older ones will have a transformer. Newer ones a SMPS - smaller and
lighter.

All wallwarts use a transformer. SMPSes just use a smaller one.


NT

wrote in message
...
On Tuesday, 29 January 2019 17:09:04 UTC, Dave Plowman (News) wrote:
In article ,
R D S wrote:
And why do similar rated ones differ so much in bulk? Is this just a
build quality issue?

Older ones will have a transformer. Newer ones a SMPS - smaller and
lighter.

All wallwarts use a transformer.

Not all of them do. Some of the lower
power ones just use a capacitor dropper.

SMPSes just use a smaller one.

Wrong, as always.

On Wednesday, 30 January 2019 04:16:40 UTC, Rod Speed wrote:
tabbypurr wrote in message
...
On Tuesday, 29 January 2019 17:09:04 UTC, Dave Plowman (News) wrote:
In article ,
R D S wrote:

And why do similar rated ones differ so much in bulk? Is this just a
build quality issue?

Older ones will have a transformer. Newer ones a SMPS - smaller and
lighter.

All wallwarts use a transformer.

those aren't legal here

Not all of them do. Some of the lower
power ones just use a capacitor dropper.

SMPSes just use a smaller one.

Wrong, as always.

you are, as usual.

wrote in message
...
On Wednesday, 30 January 2019 04:16:40 UTC, Rod Speed wrote:
tabbypurr wrote in message
...
On Tuesday, 29 January 2019 17:09:04 UTC, Dave Plowman (News) wrote:
In article ,
R D S wrote:

And why do similar rated ones differ so much in bulk? Is this just a
build quality issue?

Older ones will have a transformer. Newer ones a SMPS - smaller and
lighter.

All wallwarts use a transformer.

those aren't legal here

Bull****.

Not all of them do. Some of the lower
power ones just use a capacitor dropper.

SMPSes just use a smaller one.

Wrong, as always.

you are, as usual.

Wrong, as always.

On Wednesday, 30 January 2019 04:16:40 UTC, Rod Speed wrote:
wrote in message
...
On Tuesday, 29 January 2019 17:09:04 UTC, Dave Plowman (News) wrote:
In article ,
R D S wrote:
And why do similar rated ones differ so much in bulk? Is this just a
build quality issue?

Older ones will have a transformer. Newer ones a SMPS - smaller and
lighter.

All wallwarts use a transformer.

Not all of them do. Some of the lower
power ones just use a capacitor dropper.

How do they work then ?
How do you know what voltage they produce and how will it convert the AC to DC.



SMPSes just use a smaller one.

Wrong, as always.

They mostly use smaller transformers and therefore lighter than the older sytle linear ones.

"whisky-dave" wrote in message
...
On Wednesday, 30 January 2019 04:16:40 UTC, Rod Speed wrote:
wrote in message
...
On Tuesday, 29 January 2019 17:09:04 UTC, Dave Plowman (News) wrote:
In article ,
R D S wrote:
And why do similar rated ones differ so much in bulk? Is this just a
build quality issue?

Older ones will have a transformer. Newer ones a SMPS - smaller and
lighter.

All wallwarts use a transformer.

Not all of them do. Some of the lower
power ones just use a capacitor dropper.

How do they work then ?

The capacitance determines the AC current.

How do you know what voltage they produce

They are regulated after the cap.

and how will it convert the AC to DC.

There's rectification for that.

SMPSes just use a smaller one.

Wrong, as always.

They mostly use smaller transformers and
therefore lighter than the older sytle linear ones.

Duh, but not ALWAYS as the cat claimed.

On Wednesday, 30 January 2019 13:39:43 UTC, whisky-dave wrote:
On Wednesday, 30 January 2019 04:16:40 UTC, Rod Speed wrote:
tabbypurr wrote in message
...
On Tuesday, 29 January 2019 17:09:04 UTC, Dave Plowman (News) wrote:
In article ,
R D S wrote:

And why do similar rated ones differ so much in bulk? Is this just a
build quality issue?

Older ones will have a transformer. Newer ones a SMPS - smaller and
lighter.

All wallwarts use a transformer.

Not all of them do. Some of the lower
power ones just use a capacitor dropper.

How do they work then ?
How do you know what voltage they produce and how will it convert the AC to DC.



SMPSes just use a smaller one.

Wrong, as always.

They mostly use smaller transformers and therefore lighter than the older sytle linear ones.

they don't mostly use them, they always use them. It's how isolating SMPSUs work.


NT

On 30/01/2019 23:19, wrote:
On Wednesday, 30 January 2019 13:39:43 UTC, whisky-dave wrote:
On Wednesday, 30 January 2019 04:16:40 UTC, Rod Speed wrote:
tabbypurr wrote in message
...
On Tuesday, 29 January 2019 17:09:04 UTC, Dave Plowman (News) wrote:
In article ,
R D S wrote:

And why do similar rated ones differ so much in bulk? Is this just a
build quality issue?

Older ones will have a transformer. Newer ones a SMPS - smaller and
lighter.

All wallwarts use a transformer.

Not all of them do. Some of the lower
power ones just use a capacitor dropper.

How do they work then ?
How do you know what voltage they produce and how will it convert the AC to DC.



SMPSes just use a smaller one.

Wrong, as always.

They mostly use smaller transformers and therefore lighter than the older sytle linear ones.

they don't mostly use them, they always use them. It's how isolating SMPSUs work.



Afraid not. You are in for a surprise if you look inside some of the
cheap 'Chinese' wall warts.

Of course, they aren't then isolating PSUs but how often do they claim
to be?

Likewise, things like 'Smart' light bulbs which require a low voltage to
power the 'Smart' circuitry, don't bother with a transformer- sometimes
just a crude resistor and zener, others use one of the (cheap) chips
designed to implement simple PSUs, like the LM2575.




--
Always smile when walking, you never know where there is a camera ;-)

Remarkable Coincidences:
The Stock Market Crashes of 1929 and 2008 happened on the same
date in October. In Oct 1907, a run on the Knickerbocker Trust
Company led to the Great Depression.

On Wednesday, 30 January 2019 23:41:46 UTC, Brian Reay wrote:
On 30/01/2019 23:19, tabbypurr wrote:
On Wednesday, 30 January 2019 13:39:43 UTC, whisky-dave wrote:
On Wednesday, 30 January 2019 04:16:40 UTC, Rod Speed wrote:
tabbypurr wrote in message
...
On Tuesday, 29 January 2019 17:09:04 UTC, Dave Plowman (News) wrote:
In article ,
R D S wrote:

And why do similar rated ones differ so much in bulk? Is this just a
build quality issue?

Older ones will have a transformer. Newer ones a SMPS - smaller and
lighter.

All wallwarts use a transformer.

Not all of them do. Some of the lower
power ones just use a capacitor dropper.

How do they work then ?
How do you know what voltage they produce and how will it convert the AC to DC.



SMPSes just use a smaller one.

Wrong, as always.

They mostly use smaller transformers and therefore lighter than the older sytle linear ones.

they don't mostly use them, they always use them. It's how isolating SMPSUs work.



Afraid not. You are in for a surprise if you look inside some of the
cheap 'Chinese' wall warts.

Of course, they aren't then isolating PSUs but how often do they claim
to be?

not legal here

Likewise, things like 'Smart' light bulbs which require a low voltage to
power the 'Smart' circuitry, don't bother with a transformer- sometimes
just a crude resistor and zener, others use one of the (cheap) chips
designed to implement simple PSUs, like the LM2575.

A lightbulb is not a wallwart. Wallwarts require isolation.


NT

wrote in message
...
On Wednesday, 30 January 2019 13:39:43 UTC, whisky-dave wrote:
On Wednesday, 30 January 2019 04:16:40 UTC, Rod Speed wrote:
tabbypurr wrote in message
...
On Tuesday, 29 January 2019 17:09:04 UTC, Dave Plowman (News) wrote:
In article ,
R D S wrote:

And why do similar rated ones differ so much in bulk? Is this just
a
build quality issue?

Older ones will have a transformer. Newer ones a SMPS - smaller and
lighter.

All wallwarts use a transformer.

Not all of them do. Some of the lower
power ones just use a capacitor dropper.

How do they work then ?
How do you know what voltage they produce and how will it convert the AC
to DC.



SMPSes just use a smaller one.

Wrong, as always.

They mostly use smaller transformers and therefore lighter than the older
sytle linear ones.

they don't mostly use them, they always use them.

No they dont with the always. Have a look at some of Big Clive's teardowns
sometime.

It's how isolating SMPSUs work.

But isnt the only way wall warts are done.

wrote in message
...
On Wednesday, 30 January 2019 23:41:46 UTC, Brian Reay wrote:
On 30/01/2019 23:19, tabbypurr wrote:
On Wednesday, 30 January 2019 13:39:43 UTC, whisky-dave wrote:
On Wednesday, 30 January 2019 04:16:40 UTC, Rod Speed wrote:
tabbypurr wrote in message
...
On Tuesday, 29 January 2019 17:09:04 UTC, Dave Plowman (News)
wrote:
In article ,
R D S wrote:

And why do similar rated ones differ so much in bulk? Is this just
a
build quality issue?

Older ones will have a transformer. Newer ones a SMPS - smaller and
lighter.

All wallwarts use a transformer.

Not all of them do. Some of the lower
power ones just use a capacitor dropper.

How do they work then ?
How do you know what voltage they produce and how will it convert the
AC to DC.



SMPSes just use a smaller one.

Wrong, as always.

They mostly use smaller transformers and therefore lighter than the
older sytle linear ones.

they don't mostly use them, they always use them. It's how isolating
SMPSUs work.



Afraid not. You are in for a surprise if you look inside some of the
cheap 'Chinese' wall warts.

Of course, they aren't then isolating PSUs but how often do they claim
to be?

not legal here

Thats a lie.

Likewise, things like 'Smart' light bulbs which require a low voltage to
power the 'Smart' circuitry, don't bother with a transformer- sometimes
just a crude resistor and zener, others use one of the (cheap) chips
designed to implement simple PSUs, like the LM2575.

A lightbulb is not a wallwart. Wallwarts require isolation.

No they do not.

On 31/01/2019 15:10, whisky-dave wrote:
On Thursday, 31 January 2019 11:44:36 UTC, Martin Brown wrote:
On 30/01/2019 13:39, whisky-dave wrote:
On Wednesday, 30 January 2019 04:16:40 UTC, Rod Speed wrote:
wrote in message
...
On Tuesday, 29 January 2019 17:09:04 UTC, Dave Plowman (News) wrote:
In article ,
R D S wrote:
And why do similar rated ones differ so much in bulk? Is this just a
build quality issue?

Older ones will have a transformer. Newer ones a SMPS - smaller and
lighter.

All wallwarts use a transformer.

Not all of them do. Some of the lower
power ones just use a capacitor dropper.

How do they work then ?

Did they not teach you the impedance of a capacitor then?

Well yes but it's really Reactance you're refering to isn't it.

And we donlt in the UK for wall marts use capacitors to drop the voltage.



It is a potential divider for AC implemented with capacitors rather than
resistors. It is the capacitive equivalent of an autotransformer.

except they aren't really used , it;s OK in theory for an idea capacitor but they don't exist in the real world.



Snag is that there is no isolation of the mains this way.

Another reason we donlt use them in the UK.

The "low
voltage" output can find itself at mains potential if the wrong
capacitor fails open circuit. Killed some Apple user in the bath.

https://www.telegraph.co.uk/news/201...g-iphone-bath/

I actually fail to see how he was killed by a genuine Apple charging
device - all the ones I have seen were properly engineered.

Not a very good report is it.
It shows the headphone to lightning adapter as the charger ?
It also says that the charger was in the bath which is a differnt type of accident, and what;'s this extention cord they are refering to ?


"We found an iPhone plugged into the extension cable and then the charger element in the bath," he explained."


How do you know what voltage they produce and how will it convert the AC to DC.

Electronic engineering and rather simple formulae.

Which only works in theory NOT in the real world unless you;re making cheap chinese chargers.
The forst enalrger timer I built from a magazine used a 10W 33K dropper resistor to power a 555.

I used to have a battery charger for NiCd button cells that consisted of
a resistor and a diode. In a ventilated plastic case with a little
carrier thing to insert the cell. (Used for a teeny Russian LW/MW
personal radio about 1"x3/4"x1/4" which used thin film integration and
six transistors.)

--
Max Demian

"whisky-dave" wrote in message
...
On Wednesday, 30 January 2019 19:37:07 UTC, Rod Speed wrote:
"whisky-dave" wrote in message
...
On Wednesday, 30 January 2019 04:16:40 UTC, Rod Speed wrote:
wrote in message
...
On Tuesday, 29 January 2019 17:09:04 UTC, Dave Plowman (News)
wrote:
In article ,
R D S wrote:
And why do similar rated ones differ so much in bulk? Is this
just a
build quality issue?

Older ones will have a transformer. Newer ones a SMPS - smaller and
lighter.

All wallwarts use a transformer.

Not all of them do. Some of the lower
power ones just use a capacitor dropper.

How do they work then ?

The capacitance determines the AC current.

But most devices are voltage driver.

Thats why you rectify and regulate it after the cap, stupid.

"whisky-dave" wrote in message
...
On Thursday, 31 January 2019 11:44:36 UTC, Martin Brown wrote:
On 30/01/2019 13:39, whisky-dave wrote:
On Wednesday, 30 January 2019 04:16:40 UTC, Rod Speed wrote:
wrote in message
...
On Tuesday, 29 January 2019 17:09:04 UTC, Dave Plowman (News) wrote:
In article ,
R D S wrote:
And why do similar rated ones differ so much in bulk? Is this just
a
build quality issue?

Older ones will have a transformer. Newer ones a SMPS - smaller and
lighter.

All wallwarts use a transformer.

Not all of them do. Some of the lower
power ones just use a capacitor dropper.

How do they work then ?

Did they not teach you the impedance of a capacitor then?

Well yes but it's really Reactance you're refering to isn't it.

And we donlt in the UK for wall marts use capacitors to drop the voltage.

Wrong, as always.

It is a potential divider for AC implemented with capacitors rather than
resistors. It is the capacitive equivalent of an autotransformer.

except they aren't really used ,

Corse they are.

it;s OK in theory for an idea capacitor
but they don't exist in the real world.

Doesnt have to be an ideal capacitor.

Snag is that there is no isolation of the mains this way.

Another reason we donlt use them in the UK.

Wrong, as always.

The "low voltage" output can find itself at mains potential if the wrong
capacitor fails open circuit. Killed some Apple user in the bath.

https://www.telegraph.co.uk/news/201...g-iphone-bath/

I actually fail to see how he was killed by a genuine Apple charging
device - all the ones I have seen were properly engineered.

Not a very good report is it.
It shows the headphone to lightning adapter as the charger ?
It also says that the charger was in the bath which is a differnt
type of accident, and what;'s this extention cord they are refering to ?

"We found an iPhone plugged into the extension cable
and then the charger element in the bath," he explained."

How do you know what voltage they produce and how will it convert the
AC to DC.

Electronic engineering and rather simple formulae.

Which only works in theory NOT in the real world
unless you;re making cheap chinese chargers.

Still the real world.

The forst enalrger timer I built from a magazine
used a 10W 33K dropper resistor to power a 555.

And a capacitor works much better.

On 31/01/2019 12:42, Andrew Gabriel wrote:
Sounds a bit like my Bremshey.

It is a Bremshey.

On Thursday, 31 January 2019 18:15:46 UTC, Max Demian wrote:
On 31/01/2019 15:10, whisky-dave wrote:
On Thursday, 31 January 2019 11:44:36 UTC, Martin Brown wrote:
On 30/01/2019 13:39, whisky-dave wrote:
On Wednesday, 30 January 2019 04:16:40 UTC, Rod Speed wrote:
wrote in message
...
On Tuesday, 29 January 2019 17:09:04 UTC, Dave Plowman (News) wrote:
In article ,
R D S wrote:
And why do similar rated ones differ so much in bulk? Is this just a
build quality issue?

Older ones will have a transformer. Newer ones a SMPS - smaller and
lighter.

All wallwarts use a transformer.

Not all of them do. Some of the lower
power ones just use a capacitor dropper.

How do they work then ?

Did they not teach you the impedance of a capacitor then?

Well yes but it's really Reactance you're refering to isn't it.

And we donlt in the UK for wall marts use capacitors to drop the voltage.



It is a potential divider for AC implemented with capacitors rather than
resistors. It is the capacitive equivalent of an autotransformer.

except they aren't really used , it;s OK in theory for an idea capacitor but they don't exist in the real world.



Snag is that there is no isolation of the mains this way.

Another reason we donlt use them in the UK.

The "low
voltage" output can find itself at mains potential if the wrong
capacitor fails open circuit. Killed some Apple user in the bath.

https://www.telegraph.co.uk/news/201...g-iphone-bath/

I actually fail to see how he was killed by a genuine Apple charging
device - all the ones I have seen were properly engineered.

Not a very good report is it.
It shows the headphone to lightning adapter as the charger ?
It also says that the charger was in the bath which is a differnt type of accident, and what;'s this extention cord they are refering to ?


"We found an iPhone plugged into the extension cable and then the charger element in the bath," he explained."


How do you know what voltage they produce and how will it convert the AC to DC.

Electronic engineering and rather simple formulae.

Which only works in theory NOT in the real world unless you;re making cheap chinese chargers.
The forst enalrger timer I built from a magazine used a 10W 33K dropper resistor to power a 555.

I used to have a battery charger for NiCd button cells that consisted of
a resistor and a diode. In a ventilated plastic case with a little
carrier thing to insert the cell. (Used for a teeny Russian LW/MW
personal radio about 1"x3/4"x1/4" which used thin film integration and
six transistors.)

When was using NiCd they needed a constant current charger.
But like any battery yuo can charge it any way you lijke if your're not worried about effecincy it's life or safety.


--
Max Demian

On Thursday, 31 January 2019 18:41:05 UTC, Rod Speed wrote:
"whisky-dave" wrote in message
...
On Wednesday, 30 January 2019 19:37:07 UTC, Rod Speed wrote:
"whisky-dave" wrote in message
...
On Wednesday, 30 January 2019 04:16:40 UTC, Rod Speed wrote:
wrote in message
...
On Tuesday, 29 January 2019 17:09:04 UTC, Dave Plowman (News)
wrote:
In article ,
R D S wrote:
And why do similar rated ones differ so much in bulk? Is this
just a
build quality issue?

Older ones will have a transformer. Newer ones a SMPS - smaller and
lighter.

All wallwarts use a transformer.

Not all of them do. Some of the lower
power ones just use a capacitor dropper.

How do they work then ?

The capacitance determines the AC current.

But most devices are voltage driver.

Thats why you rectify and regulate it after the cap, stupid.

Which is why the AC current is pretty irrelivant.
When was the last time you saw a circuit or device that stated the capacitance and AC current ?

On 31/01/2019 13:31, Martin Brown wrote:
On 31/01/2019 00:29, wrote:
On Wednesday, 30 January 2019 23:41:46 UTC, Brian ReayÂ* wrote:
On 30/01/2019 23:19, tabbypurr wrote:
On Wednesday, 30 January 2019 13:39:43 UTC, whisky-daveÂ* wrote:
On Wednesday, 30 January 2019 04:16:40 UTC, Rod SpeedÂ* wrote:
tabbypurr wrote in message
...
On Tuesday, 29 January 2019 17:09:04 UTC, Dave Plowman (News)
wrote:
In article ,
Â*Â*Â*Â* R D S wrote:

And why do similar rated ones differ so much in bulk? Is this
just a
build quality issue?

Older ones will have a transformer. Newer ones a SMPS - smaller and
lighter.

All wallwarts use a transformer.

Not all of them do. Some of the lower
power ones just use a capacitor dropper.

How do they work then ?
How do you know what voltage they produce and how will it convert
the AC to DC.



SMPSes just use a smaller one.

Wrong, as always.

They mostly use smaller transformers and therefore lighter than the
older sytle linear ones.

they don't mostly use them, they always use them. It's how isolating
SMPSUs work.

Afraid not. You are in for a surprise if you look inside some of the
cheap 'Chinese' wall warts.

Of course, they aren't then isolating PSUs but how often do they claim
to be?

not legal here

They may not be legal in the UK but you can still buy them on eBay with
relative ease. CE on cheap Chinese junk does actually mean *anything*.


Exactly and, without either looking inside or some measurements, you
can't tell if one is isolated or not. Some off the 'Chinese copies' of
quality power supplies are, externally, darn near perfect copies- if not
perfect.



--
Always smile when walking, you never know where there is a camera ;-)

Remarkable Coincidences:
The Stock Market Crashes of 1929 and 2008 happened on the same
date in October. In Oct 1907, a run on the Knickerbocker Trust
Company led to the Great Depression.

On Thursday, 31 January 2019 18:55:32 UTC, Rod Speed wrote:
"whisky-dave" wrote in message
...
On Thursday, 31 January 2019 11:44:36 UTC, Martin Brown wrote:
On 30/01/2019 13:39, whisky-dave wrote:
On Wednesday, 30 January 2019 04:16:40 UTC, Rod Speed wrote:
wrote in message
...
On Tuesday, 29 January 2019 17:09:04 UTC, Dave Plowman (News) wrote:
In article ,
R D S wrote:
And why do similar rated ones differ so much in bulk? Is this just
a
build quality issue?

Older ones will have a transformer. Newer ones a SMPS - smaller and
lighter.

All wallwarts use a transformer.

Not all of them do. Some of the lower
power ones just use a capacitor dropper.

How do they work then ?

Did they not teach you the impedance of a capacitor then?

Well yes but it's really Reactance you're refering to isn't it.

And we donlt in the UK for wall marts use capacitors to drop the voltage.

Wrong, as always.

Right as always. You haven;t a clue have you.
tell you what take one aprt and show me these capacitors used to drop voltage.



The "low voltage" output can find itself at mains potential if the wrong
capacitor fails open circuit. Killed some Apple user in the bath.

https://www.telegraph.co.uk/news/201...g-iphone-bath/

I actually fail to see how he was killed by a genuine Apple charging
device - all the ones I have seen were properly engineered.

Not a very good report is it.
It shows the headphone to lightning adapter as the charger ?
It also says that the charger was in the bath which is a differnt
type of accident, and what;'s this extention cord they are refering to ?

"We found an iPhone plugged into the extension cable
and then the charger element in the bath," he explained."

See you couldn't even see through this crap.



The forst enalrger timer I built from a magazine
used a 10W 33K dropper resistor to power a 555.

And a capacitor works much better.

No it doesn't if it did we'd be using them for such things, we don't.

On 31/01/2019 10:12, The Natural Philosopher wrote:
On 31/01/2019 10:03, wrote:
On Thursday, 31 January 2019 00:57:36 UTC, Rod SpeedÂ* wrote:

... Wallwarts require isolation.

No they do not.

Would you care to explain please?

Wall warts sold in teh UK MUST have isolation between mains and the output.



Unfortunately, that doesn't mean that they all do. I recently stripped
down an Ebay special (it had a 2 pin EU plug) for the output lead/plug-
an odd size. I glanced at the PSU PCB, no transformer at all.

I've seen the same before.




--
Always smile when walking, you never know where there is a camera ;-)

Remarkable Coincidences:
The Stock Market Crashes of 1929 and 2008 happened on the same
date in October. In Oct 1907, a run on the Knickerbocker Trust
Company led to the Great Depression.

In article ,
Brian Reay wrote:
On 31/01/2019 13:31, Martin Brown wrote:
On 31/01/2019 00:29, wrote:
On Wednesday, 30 January 2019 23:41:46 UTC, Brian Reay wrote:
On 30/01/2019 23:19, tabbypurr wrote:
On Wednesday, 30 January 2019 13:39:43 UTC, whisky-dave wrote:
On Wednesday, 30 January 2019 04:16:40 UTC, Rod Speed wrote:
tabbypurr wrote in message
...
On Tuesday, 29 January 2019 17:09:04 UTC, Dave Plowman (News)
wrote:
In article ,
R D S wrote:

And why do similar rated ones differ so much in bulk? Is this
just a
build quality issue?

Older ones will have a transformer. Newer ones a SMPS - smaller and
lighter.

All wallwarts use a transformer.

Not all of them do. Some of the lower
power ones just use a capacitor dropper.

How do they work then ?
How do you know what voltage they produce and how will it convert
the AC to DC.



SMPSes just use a smaller one.

Wrong, as always.

They mostly use smaller transformers and therefore lighter than the
older sytle linear ones.

they don't mostly use them, they always use them. It's how isolating
SMPSUs work.

Afraid not. You are in for a surprise if you look inside some of the
cheap 'Chinese' wall warts.

Of course, they aren't then isolating PSUs but how often do they claim
to be?

not legal here

They may not be legal in the UK but you can still buy them on eBay with
relative ease. CE on cheap Chinese junk does actually mean *anything*.


Exactly and, without either looking inside or some measurements, you
can't tell if one is isolated or not. Some off the 'Chinese copies' of
quality power supplies are, externally, darn near perfect copies- if not
perfect.

They might even come out of the same factory, by a different loading bay.

--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle

On 01/02/2019 11:16, Brian Reay wrote:
On 31/01/2019 10:12, The Natural Philosopher wrote:
On 31/01/2019 10:03, wrote:
On Thursday, 31 January 2019 00:57:36 UTC, Rod SpeedÂ* wrote:

... Wallwarts require isolation.

No they do not.

Would you care to explain please?

Wall warts sold in teh UK MUST have isolation between mains and the
output.



Unfortunately, that doesn't mean that they all do.Â* I recently stripped
down an Ebay special (it had a 2 pin EU plug) for the output lead/plug-
an odd size. I glanced at the PSU PCB, no transformer at all.


Simply not possible.

You might not have recognised it as one..


An schuko 2 pin plug is not polarised therefore it is entirely possibkle
that were it not isolated the output could be at mains voltage.

Even the EU are not that stupid.


I've seen the same before.

But did you recognise what you saw?

A typical piece of mains switchery will have 3 magnetic components - two
in the mains fileter and one to do the transnformer bit.

These might be pretty small and potted in resin.. The transformer would
likley be 4 or 5 terminals








--
"When one man dies it's a tragedy. When thousands die it's statistics."

Josef Stalin

On 01/02/2019 11:18, charles wrote:
In article ,
Brian Reay wrote:
On 31/01/2019 13:31, Martin Brown wrote:
On 31/01/2019 00:29, wrote:
On Wednesday, 30 January 2019 23:41:46 UTC, Brian Reay wrote:
On 30/01/2019 23:19, tabbypurr wrote:
On Wednesday, 30 January 2019 13:39:43 UTC, whisky-dave wrote:
On Wednesday, 30 January 2019 04:16:40 UTC, Rod Speed wrote:
tabbypurr wrote in message
...
On Tuesday, 29 January 2019 17:09:04 UTC, Dave Plowman (News)
wrote:
In article ,
R D S wrote:

And why do similar rated ones differ so much in bulk? Is this
just a
build quality issue?

Older ones will have a transformer. Newer ones a SMPS - smaller and
lighter.

All wallwarts use a transformer.

Not all of them do. Some of the lower
power ones just use a capacitor dropper.

How do they work then ?
How do you know what voltage they produce and how will it convert
the AC to DC.



SMPSes just use a smaller one.

Wrong, as always.

They mostly use smaller transformers and therefore lighter than the
older sytle linear ones.

they don't mostly use them, they always use them. It's how isolating
SMPSUs work.

Afraid not. You are in for a surprise if you look inside some of the
cheap 'Chinese' wall warts.

Of course, they aren't then isolating PSUs but how often do they claim
to be?

not legal here

They may not be legal in the UK but you can still buy them on eBay with
relative ease. CE on cheap Chinese junk does actually mean *anything*.


Exactly and, without either looking inside or some measurements, you
can't tell if one is isolated or not. Some off the 'Chinese copies' of
quality power supplies are, externally, darn near perfect copies- if not
perfect.

They might even come out of the same factory, by a different loading bay.

I stand by my claim. An un-isolated wall wart esp with a two pin Euro
plug that puts user equipment at mains potential would not last 5
minutes ..it would be lethal

Its trivial to make an isolated one..

--
"It is an established fact to 97% confidence limits that left wing
conspirators see right wing conspiracies everywhere"

On 01/02/2019 11:41, The Natural Philosopher wrote:

I stand by my claim. An un-isolated wall wart esp with a two pin Euro
plug that puts user equipment at mains potential would not last 5
minutes ..it would be lethal

Its trivial to make an isolated one..


It maybe trivial but bigclive and others have shown ones that aren't
isolated.

On Thursday, 31 January 2019 11:27:41 UTC, Max Demian wrote:
On 31/01/2019 10:12, The Natural Philosopher wrote:
On 31/01/2019 10:03, wrote:
On Thursday, 31 January 2019 00:57:36 UTC, Rod SpeedÂ* wrote:

... Wallwarts require isolation.

No they do not.

Would you care to explain please?

Wall warts sold in teh UK MUST have isolation between mains and the output.

Either via a 50Hz mains transformer, or via a mains isolation HF ferrite
transformer.

In general to keep to that they do not have overall feedback for voltage
regulation, so that is done by the equipment they are used to supply.

I don't see how a SMPS can work without feedback from the output. Don't
they do it with an LED/light sensor pair?

Yes, smpsu wallwarts are nearly always regulated. Sm lighting 'transformers' not.


NT

"whisky-dave" wrote in message
...
On Thursday, 31 January 2019 18:41:05 UTC, Rod Speed wrote:
"whisky-dave" wrote in message
...
On Wednesday, 30 January 2019 19:37:07 UTC, Rod Speed wrote:
"whisky-dave" wrote in message
...
On Wednesday, 30 January 2019 04:16:40 UTC, Rod Speed wrote:
wrote in message
...
On Tuesday, 29 January 2019 17:09:04 UTC, Dave Plowman (News)
wrote:
In article ,
R D S wrote:
And why do similar rated ones differ so much in bulk? Is this
just a
build quality issue?

Older ones will have a transformer. Newer ones a SMPS - smaller
and
lighter.

All wallwarts use a transformer.

Not all of them do. Some of the lower
power ones just use a capacitor dropper.

How do they work then ?

The capacitance determines the AC current.

But most devices are voltage driver.

Thats why you rectify and regulate it after the cap, stupid.

Which is why the AC current is pretty irrelivant.

Corse it isnt, thats what determines what power is available.

When was the last time you saw a circuit or device
that stated the capacitance and AC current ?

With a wall wart done that way, you still have the usual
statement about the output voltage and current, stupid.

On Thursday, 31 January 2019 14:47:19 UTC, whisky-dave wrote:
On Wednesday, 30 January 2019 23:19:52 UTC, tabby wrote:
On Wednesday, 30 January 2019 13:39:43 UTC, whisky-dave wrote:
On Wednesday, 30 January 2019 04:16:40 UTC, Rod Speed wrote:
tabbypurr wrote in message
...

All wallwarts use a transformer.

Not all of them do. Some of the lower
power ones just use a capacitor dropper.

How do they work then ?
How do you know what voltage they produce and how will it convert the AC to DC.



SMPSes just use a smaller one.

Wrong, as always.

They mostly use smaller transformers and therefore lighter than the older sytle linear ones.

they don't mostly use them, they always use them. It's how isolating SMPSUs work.


NT

When there's a liklihood that the current will drawn will mostly be at the higher end of the rating they don't use small transformers to save money.

When you know a triac from a passing car let us know eh.

"whisky-dave" wrote in message
...
On Thursday, 31 January 2019 18:55:32 UTC, Rod Speed wrote:
"whisky-dave" wrote in message
...
On Thursday, 31 January 2019 11:44:36 UTC, Martin Brown wrote:
On 30/01/2019 13:39, whisky-dave wrote:
On Wednesday, 30 January 2019 04:16:40 UTC, Rod Speed wrote:
wrote in message
...
On Tuesday, 29 January 2019 17:09:04 UTC, Dave Plowman (News)
wrote:
In article ,
R D S wrote:
And why do similar rated ones differ so much in bulk? Is this
just
a
build quality issue?

Older ones will have a transformer. Newer ones a SMPS - smaller
and
lighter.

All wallwarts use a transformer.

Not all of them do. Some of the lower
power ones just use a capacitor dropper.

How do they work then ?

Did they not teach you the impedance of a capacitor then?

Well yes but it's really Reactance you're refering to isn't it.

And we donlt in the UK for wall marts use capacitors to drop the
voltage.

Wrong, as always.

tell you what take one aprt and show me
these capacitors used to drop voltage.

Big Clive has done that, mostly with chargers.

The "low voltage" output can find itself at mains potential if the
wrong
capacitor fails open circuit. Killed some Apple user in the bath.

https://www.telegraph.co.uk/news/201...g-iphone-bath/

I actually fail to see how he was killed by a genuine Apple charging
device - all the ones I have seen were properly engineered.

Not a very good report is it.
It shows the headphone to lightning adapter as the charger ?
It also says that the charger was in the bath which is a differnt
type of accident, and what;'s this extention cord they are refering to
?

"We found an iPhone plugged into the extension cable
and then the charger element in the bath," he explained."

The forst enalrger timer I built from a magazine
used a 10W 33K dropper resistor to power a 555.

And a capacitor works much better.

No it doesn't if it did we'd be using them for such things, we don't.

Done quite a bit with internal power supplys for lower power devices.

On Friday, 1 February 2019 11:11:25 UTC, whisky-dave wrote:
On Thursday, 31 January 2019 18:55:32 UTC, Rod Speed wrote:
"whisky-dave" wrote in message
...

And we donlt in the UK for wall marts use capacitors to drop the voltage.

Wrong, as always.

Right as always. You haven;t a clue have you.

neither of you has


The forst enalrger timer I built from a magazine
used a 10W 33K dropper resistor to power a 555.

And a capacitor works much better.

No it doesn't if it did we'd be using them for such things, we don't.

that's naive

On Friday, 1 February 2019 11:41:42 UTC, The Natural Philosopher wrote:

I stand by my claim. An un-isolated wall wart esp with a two pin Euro
plug that puts user equipment at mains potential would not last 5
minutes ..it would be lethal

Its trivial to make an isolated one..

Yup. I have however come across a CR PSU that had droppers on both poles. I_out was low enough to not shock.


NT

On Friday, 1 February 2019 18:37:49 UTC, wrote:
On Friday, 1 February 2019 11:41:42 UTC, The Natural Philosopher wrote:

I stand by my claim. An un-isolated wall wart esp with a two pin Euro
plug that puts user equipment at mains potential would not last 5
minutes ..it would be lethal

Its trivial to make an isolated one..

Yup. I have however come across a CR PSU that had droppers on both poles. I_out was low enough to not shock.


NT

What was that used for?

"The Natural Philosopher" wrote in message
...
On 01/02/2019 11:16, Brian Reay wrote:
On 31/01/2019 10:12, The Natural Philosopher wrote:
On 31/01/2019 10:03, wrote:
On Thursday, 31 January 2019 00:57:36 UTC, Rod Speed wrote:

... Wallwarts require isolation.

No they do not.

Would you care to explain please?

Wall warts sold in teh UK MUST have isolation between mains and the
output.



Unfortunately, that doesn't mean that they all do. I recently stripped
down an Ebay special (it had a 2 pin EU plug) for the output lead/plug-
an odd size. I glanced at the PSU PCB, no transformer at all.

Simply not possible.

Yes it is with a capacitor dropper followed by a rectifier and regulator.

You might not have recognised it as one..

An schuko 2 pin plug is not polarised therefore it is entirely possibkle
that were it not isolated the output could be at mains voltage.

Even the EU are not that stupid.

But plenty of the chinese are and you can see them
in Big Clive's teardowns.

I've seen the same before.

But did you recognise what you saw?

Big Clive does.

A typical piece of mains switchery will have 3 magnetic components - two
in the mains fileter and one to do the transnformer bit.

But there are some that arent typical.

These might be pretty small and potted in resin.. The transformer would
likley be 4 or 5 terminals