"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