12v AC to DC ??

pcatterall said:
Thought I'd solved my extractor fan problem by buying a 12volt batroom one.
Silly boy!!........... its AC of course!! Is there an inexpensive rectifier I can get!!
Thanks
Click to expand...

The fan you bought is AC.. If you want to run it on Dc you will need an inverter not a rectifier. But they usually produce mains voltage AC

Fit it in your bathroom, Buy a 12 volt DC fan.
 
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pcatterall said:
Thought I'd solved my extractor fan problem by buying a 12volt batroom one.
Silly boy!!........... its AC of course!! Is there an inexpensive rectifier I can get!!
Thanks
Click to expand...

You need a 12v dc to mains inverter to run the fans mains transformer.
Ring sell one of about 75watts (way more than you need) for about £20. Try Amazon or Ebay.

Asda/ BnQ may have some drinks can sized ones for similar money.
 
12v AC or DC

What a confusing post. I can imagine that with so many halogen lights now running on 12v AC that they might make and sell a fan for 12v AC. AC can be very nice for small motors as they can use the induction (squirel cage) type motor with no brushes. Anyway if you want to run it on your boat one point is that these induction motors do not like the output of a cheap "modified sine wave" inverter. They are inefficient and motor gets hot. You will need a true sine wave inverter and of course then a transformer to reduce the 240v to 12v AC. So yes much better with a 12v DC fan.
Of course if it is for your house and it is a 12vdc fan and you wan to run it on 240vAC you need a transformer and rectifier or easiest one of those wall plugs producing 12vDC at the required current. good luck olewill
 
William_H said:
What a confusing post. I can imagine that with so many halogen lights now running on 12v AC that they might make and sell a fan for 12v AC. AC can be very nice for small motors as they can use the induction (squirel cage) type motor with no brushes. Anyway if you want to run it on your boat one point is that these induction motors do not like the output of a cheap "modified sine wave" inverter. They are inefficient and motor gets hot. You will need a true sine wave inverter and of course then a transformer to reduce the 240v to 12v AC. So yes much better with a 12v DC fan.
Of course if it is for your house and it is a 12vdc fan and you wan to run it on 240vAC you need a transformer and rectifier or easiest one of those wall plugs producing 12vDC at the required current. good luck olewill
Click to expand...
Not surprised you're puzzled. Suggest your post displays this.
Never HEARD of 12v ac as a standard or of 24v ac.

UK ac standard is 230v @50 cycles as is most of Europe
US is 110v @60 cycles as are very few others.

Halogen bulbs come in 12v, 24v dc and 230v ac (and though I'm not familiar with the US probably 110V).
As another suggested, ditch the extractor for use as envisaged and buy a native 12v extractor.
In view of the apparent confusion amongst posters it's almost inevitable that an EC directive will be published shortly excluding electrical DIY on boats as on houses.
 
charles_reed said:
Never HEARD of 12v ac as a standard or of 24v ac.
Click to expand...

Well, my bathroom fan runs on AC at two different (low) voltages, for two different speeds. Can't remember exactly what voltages, think it might have been 7v for low speed and 24v for boost when the shower is in use. There's a power supply in the attic to produce these. The reason for low voltage (or rather, "Safety Extra Low Voltage" to electricians) is so it can be mounted in a shower area without worrying about shock.

charles_reed said:
UK ac standard is 230v @50 cycles as is most of Europe
Click to expand...

Well, that's the UK mains standard. It doesn't preclude the use of alternating current at any other voltage that happens to be convenient. Nothing says that low voltage has to be DC and high voltage has to be AC. As well as fans and low-voltage halogens which I think are often AC (older sets used straight transformers, so must be), trains round here use 400v DC or something like that.

charles_reed said:
As another suggested, ditch the extractor for use as envisaged and buy a native 12v extractor.
Click to expand...

Totally agree with that one :). The conversion will cost more than buying the right fan in the first place.

charles_reed said:
In view of the apparent confusion amongst posters it's almost inevitable that an EC directive will be published shortly excluding electrical DIY on boats as on houses.
Click to expand...

Part P was nothing to do with Europe. A combination of an MP's daughter being electrocuted due to a cable having been run diagonally across a wall (by a pro electrician, so let's make life hard for amateurs :confused:) and electrical trade bodies lobbying for a rule that pushes more work towards their members.

Pete
 
Thanks chaps. My post was not clear; appologies. I needed a 12 volt extractor fan which would fit up the ' hole' in my aft cabin vent.
The 12 volt fans supplied for bathrooms seemed just the job, fitting the hole exactly and having a neat box on the outside ( and more power than the computor fans that I had considered.
These fans are 12 volts for safety and the 240 to 12 volt transformer is fitted outside the bathroom.
Sorry for the confusion, I will search for the 'proper' 12 volt extractor and no doubt pay lots of dosh.
Thanks again
 
pcatterall said:
Thanks chaps. My post was not clear; appologies. I needed a 12 volt extractor fan which would fit up the ' hole' in my aft cabin vent.
The 12 volt fans supplied for bathrooms seemed just the job, fitting the hole exactly and having a neat box on the outside ( and more power than the computor fans that I had considered.
These fans are 12 volts for safety and the 240 to 12 volt transformer is fitted outside the bathroom.
Sorry for the confusion, I will search for the 'proper' 12 volt extractor and no doubt pay lots of dosh.
Thanks again
Click to expand...

I'm surprised that the fan requires 12v AC. Everything I have seen so far is with a transformer is dc.
 
I was responding to boathook. (it is indeed a confusing thread!).

A 12vdc fan would be more appropriate.
 
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