"The Natural Philosopher" wrote in message
...
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

Doesnt matter where you stand, Big Clive has proved that some
of the chinese ones are done like that.

Its trivial to make an isolated one..

But that costs more.

On Friday, 1 February 2019 18:27:21 UTC, Rod Speed wrote:
"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.

But not from the DC perspective as that is what is important NOT the input.


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.


Yes the output curent and voltage is important, you by based on that.

On Friday, 1 February 2019 18:29:16 UTC, wrote:
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.

I do you don't.