Converting DC to AC

SarahFair · Jun 27, 2016

I bought an antique fan. Someone told me it was a DC fan and Ill have to convert it to AC.

The wires were frayed and the plugger was not there so I just hooked it up to an old extension cord and plugged it in.
When I turned the fan on it only ran on the 3rd speed but there were sparks with inside the motor box.

I unplugged it, waiting a few minutes and plugged it back in. This time when I turned it on it didnt run then the cord blew in half.

K.

Im going to be ordering a new cord for it.

How do I know if this is a DC and what do I need to convert it?

ryanh487 · Jun 27, 2016

Ok, it's really not too difficult to do, but you need to know the amperage of the fan. I've converted many DC powered computer fans to AC for use on aquarium lights, but they were very low amperage and a cheap cell phone charger was able to be used.

Any rechargeable battery charger is essentially an AC to DC converter. If you find one with the right amperage, just cut off the end of the cord and wire the fan cord to it. Positive to positive, negative to negative. Keep in mind that this will not pass any sort of home inspection so don't put it on anything that will be permanently mounted to the house. Also, I am not responsible if you mess up and burn the house down. Use proper wire connections (solder or at the very minimum crimp splices) and insulate properly with heat shrink, being sure to cover any bare wire.

A safer, though more involved, alternative might be to scavenge the motor out of a more modern fan and use it inside the antique, creating an AC fan. This probably wouldn't be too difficult but without putting hands on the fan in question I couldn't walk you through it.

mattech · Jun 27, 2016

Sounds like you may have already killed the motor.

SarahFair · Jun 27, 2016

mattech said:
Sounds like you may have already killed the motor.

have some faith! ::ke:

I think the cord just shorted out.

T-N-T · Jun 27, 2016

Does it smell burnt in there? If so, could be a bad day for the motor.

SarahFair · Jun 27, 2016

No burning smell

Flaustin1 · Jun 27, 2016

Probably just fried the brushes.

MudDucker · Jun 28, 2016

Careful!

Jake Allen · Jun 28, 2016

If the fan carried a 2, or 3 prong cord I would guess it was never direct current. IF there is not a plate with specs, I would assume nothing.
I would replace the motor or leave it alone.

biggsteve · Jun 28, 2016

who told you it was a DC fan?

I've been messin' with antiques for over 50 years, and DC fans are quite rare.

SarahFair · Jun 29, 2016

A forum Im apart of.
Im going to start cleaning it up and open it up tomorrow to see whats going on in there.

notnksnemor · Jun 29, 2016

SarahFair said:
A forum Im apart of.
Im going to start cleaning it up and open it up tomorrow to see whats going on in there.

Be very careful.
DC is more dangerous than AC.
AC lets go of you 60 times a second.

Anvil Head · Jun 29, 2016

Check the source. Where did it come from and where was it used.
Some old campers and houseboats had DC fans. There should be a tag or label somewhere.
Just remember - hospitals and graveyards are full of folks that messed with something they didn't quite understand.

I'd recommend taking it to a small appliance repairman for a look see as to whether it's AC or DC and if you burned up the windings or brushes before I went any further.
For what you might get restoring the fan may not be enough to cover time/energy/doctor bills/insurance deductibles/etc.

SarahFair · Jun 29, 2016

This is the stamp on the outside.

K80Shooter · Jun 29, 2016

It looks to me like the label states 110 volts which is AC, am I missing something?

gobbleinwoods · Jun 29, 2016

K80Shooter said:
It looks to me like the label states 110 volts which is AC, am I missing something?

That is the way I read the plate too.

Nugefan · Jun 29, 2016

gobbleinwoods said:
That is the way I read the plate too.

me 3 ....

SarahFair · Jun 29, 2016

K80Shooter said:
It looks to me like the label states 110 volts which is AC, am I missing something?

gobbleinwoods said:
That is the way I read the plate too.

A couple people kept asking me if it was dc after seeing the plate

So if I order this cord for it it should work?
http://m.ebay.com/itm/191903022188?_mwBanner=1

notnksnemor · Jun 29, 2016

From what you have described it appears to be a 3 speed AC motor.
It sounds like 2 of the speeds were shot when you say it would only run on the 3rd speed. It sounds like the motor completely went out when it burned the cord in two.
Before you plug it in again I would suggest (with the fan unplugged) taking a volt/ohm meter set on ohms and checking the resistance between the 2 wires of cord. With the switch set on, and still unplugged, you should read relatively low resistance. 10 ohms or less would be my guess. If you get no reading the motor windings are shot. If you get a good reading, check each wire to the metal housing of the fan. You should get no reading. If you get a low resistance reading, the motor is shorted to ground (the housing).
Please do this, or have someone do it, before trying to run it again.

Jim Baker · Jun 29, 2016

NOTNKSNEMOR said:
From what you have described it appears to be a 3 speed AC motor.
It sounds like 2 of the speeds were shot when you say it would only run on the 3rd speed. It sounds like the motor completely went out when it burned the cord in two.
Before you plug it in again I would suggest (with the fan unplugged) taking a volt/ohm meter set on ohms and checking the resistance between the 2 wires of cord. With the switch set on, and still unplugged, you should read relatively low resistance. 10 ohms or less would be my guess. If you get no reading the motor windings are shot. If you get a good reading, check each wire to the metal housing of the fan. You should get no reading. If you get a low resistance reading, the motor is shorted to ground (the housing).
Please do this, or have someone do it, before trying to run it again.

Exactly. Electricity is nothing to be unsure of.

Converting DC to AC

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