# Use 5V AC adapter in place of 3V AC adapter



## alicez (Jul 12, 2008)

I have 5V AC adapter with USB connection on one side and the two plugs for the AC outlet on the other. My appliance (Small fan) says it needs 3V AC adapter. I only have 5V (output) AC adapters.
I plugged the appliance into the USB port of the 5V adapter and plugged the AC adapter into the AC wall outlet. And the appliance is working. 
Is it okay to use the 5V AC adapter in place of the the 3V AC adapter, which I do not have?
Or do I have to buy a new 3V AC adapter?


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## mpeet611 (Dec 16, 2013)

If your not having a problem using your appliance with the 5V AC Adapter i would use the adapter your using now.


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## Drabdr (Nov 26, 2007)

If it was mine, I wouldn't use it. That's a greater than 200% jump. 

If you're going to use it, I'd make sure I wouldn't use it without being supervised.


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## DaveBurnett (Nov 11, 2002)

It is a 66% jump not 200%.

USB is 5v DC not AC.

I would not use it -especially unsupervised - until you have the proper power supply. AC adapters are not expensive.


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## Drabdr (Nov 26, 2007)

DaveBurnett said:


> It is a 66% jump not 200%.


Yes. I stand corrected. I was thinking 2 volts on my mind... actually, I don't know what I was thinking. (doubling 2 or something).
Thanks for catching that. :up:

Nominal voltage is usually got a spread of around 10%.

Some devices (made for a universal audience) have a pretty flexible voltage requirement. However, it would be stamped on the device. If it says 3 volts (especially with a given amperage listed), that's what I would use.


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## Johnny2K (Aug 28, 2013)

alicez said:


> I have 5V AC adapter with USB connection on one side and the two plugs for the AC outlet on the other. My appliance (Small fan) says it needs 3V AC adapter. I only have 5V (output) AC adapters


Something doesn't make sense.

Your '5V AC adapter with USB connection on one side' should be outputting ~5V *DC*, not AC. It should say on it. Don't think I've ever seen USB used with AC output.


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## alicez (Jul 12, 2008)

I didn't think my question would result in so many answers. The cord that came with the small fan has a USB plug that I can plug into the USB port on my computer. I was advised that the cord could also be plugged into a 3v AC adapter (which had USB input connection on it).
I am confused now.


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## DaveBurnett (Nov 11, 2002)

I would imagine that mains adapter has dual function and outputs both 3v AC and 5v DC for the USB connector.

It should, by law, have details printed on it somewhere. If it does not, I suggest that maybe it is an illegal knock off and you should be very careful with it.


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## Johnny2K (Aug 28, 2013)

alicez said:


> I didn't think my question would result in so many answers. The cord that came with the small fan has a USB plug that I can plug into the USB port on my computer. I was advised that the cord could also be plugged into a 3v AC adapter (which had USB input connection on it).


If you can plug into to your computer it's running off ~5V DC. AC *output* adapters do not use the USB interface. All small fans with a USB cord are made to run on DC.

All of these run off a 5V DC source.

https://www.google.com/search?q=usb...a=X&ei=DNYtVISbAtawyATF7oKYCw&ved=0CAcQ_AUoAg


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## alicez (Jul 12, 2008)

As I said, I didn't think this question would generate so many replies.
The back of the fan has a round 'hole' where you plug in one end of the cord/cable that came with the fan. The hole on the fan has "3V" imprinted over it.
The other end of the cord/cable has a USB plug that can be plugged into computer USB port, or as the fan instructions mentioned, can be plugged into a AC adapter. They didn't include an adapter and that is what I was originally trying to find out if I could purchase a 3V AC/USB adapter. (An AC plug that has an input for USB cable.)
The instructions say: "operates with 2 AA batteries, a USB connection or an AC adapter"


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## DaveBurnett (Nov 11, 2002)

When it says AC adapter, the AC bit is the mains and the ADAPTER bit means change the voltage and possibly AC to DC.
A DC motor will not run at all with AC (and vice versa), but a small fan may well be designed to run of 5V DC and will still work, but slower, off 3V DC

That cable may well have a small resistor in it to drop the voltage to 3v.

The fact that it will run off 2 AA batteries also implies that it is 3V DC


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## alicez (Jul 12, 2008)

Just too confusing for this simple mind of mine.


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## cwwozniak (Nov 29, 2005)

If the cable that came with the fan has a standard USB plug that fits into a USB port on a computer, you should be able to use an AC power adapter that has a USB jack on it that looks exactly like the USB port on the computer. These types of adapters are very common and sold as cell phone chargers, for use with a customer supplied cable. To be safe, you might want to get one rated with at least a 200 mA output. That should be able to handle any high inrush current when the fan first starts. Any decent sized general merchandise store like Wal-Mart or specialty store like Best Buy should sell them. A drug store like Walgreens or CVS might sell them as well.


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