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From: Sylvia Else on 24 Jun 2010 22:57
On 25/06/2010 10:37 AM, PeterD wrote:
> On Thu, 24 Jun 2010 23:04:00 +1000, Sylvia Else
> <sylvia(a)not.here.invalid> wrote:
>
>> On 24/06/2010 9:46 PM, PeterD wrote:
>>> On Thu, 24 Jun 2010 15:29:35 +1000, Sylvia Else
>>> <sylvia(a)not.here.invalid> wrote:
>>>
>>>> On 24/06/2010 3:04 PM, Steve Sousa wrote:
>>>>> Hello:
>>>>>
>>>>> I live in a 230V area but need to use a 120V fan to repair an amplifier.
>>>>> I can only get 230V fan motors here, so i was wondering if i can simply
>>>>> remove turns from a 230v shaded pole motor to make it into a 120v one?
>>>>>
>>>>> Thank you.
>>>>>
>>>>>
>>>>
>>>> No. It's highly unlikely that the wire used in the motor is more than
>>>> 100% overspecified, so if you remove turns from it to make it run at the
>>>> same speed on 120v, it will overheat, because the current will
>>>> approximately double.
>>>>
>>>> Sylvia.
>>>
>>> There is one high labor alternative that might work...
>>>
>>> Take the current wire on the motor, and find the center, break it at
>>> that point, so you have two 120 volt windings. Put in parallel for 120
>>> volts, and series for 240 volts.
>>>
>>> But, IMHO, hardly worth the effort, but technically feasible.
>>
>> I'm not sure it's advisable either. There's every chance the enamel will
>> be damaged in the process. If he's lucky, any short will appear as soon
>> as he turns it on. If he's unlucky, it will occur when he's not looking.
>>
>> Sylvia.
>
> Advisable, probably not, but a theoritical solution, however!<bg>

That I agree with.

Sylvia.
From: Robert Macy on 25 Jun 2010 03:36
On Jun 24, 5:12 pm, "Phil Allison" <phi...(a)tpg.com.au> wrote:
> "Robert Macy"
> "Steve Sousa"
>
>
>
> > I live in a 230V area but need to use a 120V fan to repair an amplifier..
> > I can only get 230V fan motors here, so i was wondering if i can simply
> > remove turns from a 230v shaded pole motor to make it into a 120v one?
>
> do you have room for other components? use two identical fans wired in
> series?
>
> ** Read the question - idiot.
>
>  The OP needs a 120 volt fan and has not got one.
>
> or, use a 120/120 isolation transformer with 230 across both [properly
> phased] and tap off the 115 for the fan, or, add a series inductor?
>
> ** Read the question - idiot.
>
>  The OP needs a 120 volt fan and has not got one.
>
>  Jeez wot a macaroon.
>
> ....   Phil

No excuse, just braindead this afternoon! Wait that's an excuse!

From: PeterD on 25 Jun 2010 11:34
On Fri, 25 Jun 2010 11:00:46 +1000, "Phil Allison" <phil_a(a)tpg.com.au>
wrote:

>
>"Steve Sousa"
>>
>> I live in a 230V area but need to use a 120V fan to repair an amplifier.
>> I can only get 230V fan motors here, so i was wondering if i can simply
>> remove turns from a 230v shaded pole motor to make it into a 120v one?
>
>
>** That idea is never gonna work - have you ever seen the insides of such a
>fan ??
>
>One possibility is to connect a capacitor in * series * with the fan of
>such a value that it causes the inductance of the motor to resonate at the
>supply frequency. This will increase the voltage across the fan above the
>incoming supply.
>
>A 230 volt, 120mm fan I tried resonates with about 3uF in series.
>
>With 120 volts AC input, the voltage across the fan became 165 volts and the
>speed was then close to that with 230 volts.
>Worth a try.
>
>Use a cap rated for 240 volt AC operation.
>
>
>.... Phil
>
>
>
>

Ooh, interesting potential solution!
From: Trevor Wilson on 26 Jun 2010 16:45

"Steve Sousa" <etsteve(a)yahoo.com> wrote in message
news:4c22e757$0$77541$892e0abb(a)auth.newsreader.octanews.com...
> Hello:
>
> I live in a 230V area but need to use a 120V fan to repair an amplifier.
> I can only get 230V fan motors here, so i was wondering if i can simply
> remove turns from a 230v shaded pole motor to make it into a 120v one?
>

**That would be the insane solution. And one which won't work. You don't say
where you are, but obtaining 120VAC fans is simply not that difficult,
regardless of where you are. Alternatively, you could source a suitable DC
fan (say: 48 Volts) and use that, connected to a DC supply line within the
amp.


--
Trevor Wilson
www.rageaudio.com.au


From: Jamie on 26 Jun 2010 20:37
Trevor Wilson wrote:

> "Steve Sousa" <etsteve(a)yahoo.com> wrote in message
> news:4c22e757$0$77541$892e0abb(a)auth.newsreader.octanews.com...
>
>>Hello:
>>
>>I live in a 230V area but need to use a 120V fan to repair an amplifier.
>>I can only get 230V fan motors here, so i was wondering if i can simply
>>remove turns from a 230v shaded pole motor to make it into a 120v one?
>>
>
>
> **That would be the insane solution. And one which won't work. You don't say
> where you are, but obtaining 120VAC fans is simply not that difficult,
> regardless of where you are. Alternatively, you could source a suitable DC
> fan (say: 48 Volts) and use that, connected to a DC supply line within the
> amp.
>
>
How about using a 1:1 small xformer and doing series boost on the
secondary with the primary connected to the 120 side.. This way, a
240 volt fan can be used in a 120 volt area..

etc..
Jamie.





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