The Cyber-Spy.Com Usenet Archive Feeds Directly
From The Open And Publicly Available Newsgroup
This Group And Thousands Of Others Are Available
On Most IS NNTP News Servers On Port 119.
Cyber-Spy.Com Is NOT Responsible For Any Topic,
Opinions Or Content Posted To This Or Any Other
Newsgroup. This Web Archive Of The Newsgroup And
Posts Are For Informational Purposes Only.
From: firstname.lastname@example.org (Nico Coesel)
Subject: Re: Doubling wallwart power rating
Date: Mon, 07 Oct 2002 14:08:55 GMT
NNTP-Posting-Date: Mon, 7 Oct 2002 14:10:49 +0000 (UTC)
X-Newsreader: Forte Free Agent 1.21/32.243
email@example.com (Gibbo) wrote:
>John Woodgate firstname.lastname@example.org wrote:
>>I read in sci.electronics.design that Gibbo
>>wrote (in <email@example.com>) about 'Doubling
>>wallwart power rating', on Mon, 7 Oct 2002:
>>>Can you explain the relationship between higher current and core saturation
>>The voltage available to produce the induction in the core (equal and
>>opposite to the back-e.m.f, which may clarify the matter) is equal to
>>the supply voltage minus the voltage drop across the winding resistance.
>>A higher output current implies a higher input current, therefore more
>>voltage drop, therefore less induction.
>>Someone in this thread said that there is a compensation effect - less
>>induction implies less magnetizing current. So, over a range of output
>>currents, the input current magnitude may be nearly constant (but the
>>phase varies). Except for a very small transformer indeed, (e.g. 1 VA),
>>the magnetizing current is much less than the total input current at
>>rated load, so the constant-current range is likely to occur under some
>>rather light load conditions.
>Thanks but what I actually wanted to hear was the other posters response to the
>question. He stated that increased current draw will saturate the transformer.
>I was most interested to hear how :)
I assumed that similar problems arise like in SMPS where the current
in a given inductor is limited by core saturation.
Reply to nico@nctdevpuntnl (punt=.)
Go Back To The Cyber-Spy.Com
Usenet Web Archive Index Of
The sci.electronics.design Newsgroup