[Test-Equipment] Rewind a transformer!

[Mike Manes]

If you expect to operate a transformer, e,g, a wall wart
on 50 Hz during travels, be SURE to see that the specs show
that it will work there.  If it's spec'ed for just 60 Hz,
the iron will likely saturate and primary magnetizing current
will soar, possibly burning up the primary winding. Been there,
done that with a 120V 60Hz HT charger plugged into the 120VAC shaver
outlet in the UK - which runs 50 Hz.

The mass of the iron is primarily determined by the xformer's
VA rating.  The freq range is determined by the primary magnetizing
inductance and turns count necessary to keep under Bsat at low
freq and high line voltage spec.

73 de Mike W5VSI

On 2/13/13 11:42 PM, David wrote:
> For a given core you will but in my experience more cores are wound to
> handle 50 Hz to start with or have enough leeway that it does not
> matter.
>
> On Thu, 14 Feb 2013 14:18:57 +1100, brianclarke01 at optusnet.com.au
> wrote:
>
>>
>>
>> 	Isn't this the wrong way round? You need more iron for 50 Hz than for
>> 60 Hz.
>>
>> 	73 de Brian, VK2GCE
>>
>> ----- Original Message -----
>> From:"Discussion of Electronic Test Equipment"
>> To:"Discussion of Electronic Test Equipment"
>> Cc:
>> Sent:Wed, 13 Feb 2013 17:13:28 -0800
>> Subject:Re: [Test-Equipment] Rewind a transformer!
>>
>> On 2/13/2013 1:08 PM, David wrote:
>>> On Wed, 13 Feb 2013 10:14:40 -0800, "Randy D. Hunt"
>>>   wrote:
>>>
>>>> On 2/12/2013 11:12 PM, Dave C wrote:
>>>>> http://www.youtube.com/watch?v=ZVSbt5q0KF8
>>>>>
>>>>> Very creative...
>>>>>
>>>>> Dave
>>>>> ______________________________________________________________
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>>>> I like the idea of the transformer kit. Did anyone notice the
>>>> difference in the amount of iron in the core as compared to the
>> stock
>>>> transformer. I would say the kit has about 2/3rds of the iron. This
>>>> could be making his transformer run hot thereby causing him to have
>> to
>>>> rewind it. . . Just a thought.
>>>>
>>>> Randy, KI6WAS
>>> Presumably he adjusted the number of primary and secondary turns
>> while
>>> keeping their ratio constant to achieve the recommended magnetic
>> flux
>>> density at 50 Hz if the cross sectional area was different.
>>>
>>> Only two of the windings were moved to the transformer. He kept the
>>> old one with those two windings removed and placed the primaries of
>>> both transformers in parallel.
>>>
>> Oh, yes, 50Hz. I forgot about the lower line frequency. . .
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