u an electrician. or know about input-output on adapters?

I've got a device with fiber optic lights. It requires 12 volts.
I have two 12 volt adapters that do not seem to go to any device I have, so I'll cut the wires and try them. The device did not come with the adapter and that is why the sticker price was $49.95 and it was on sale for $5.00.

Here are my two 12 volt adapters:
1. output 12 volts >>>> DC <<<< 800 ma.
I tried this and it "appears" that the top half of center of the device, a large wreath, is dim or not lit up. It could be that there is a round flourescent tube inside that is defective, not sure. The back can not be taken off without ruining it.

I'm told the device will "only draw the current it needs."

Well, if it needs more than 800ma and the adapter I am using is 800ma output then.....?

2. The 2nd adapter is:
input 120VAC 60Hz 28VA
output 12VAC 1.67A 20VA
would this 12 volt AC output adapter work?
what does the 20VA mean?

this one would give the device twice the MA as the other one.

I just noticed that adapter #1 is 12 VDC and #2 is 12VAC. I'm guess that makes a difference but tell me any way about these adapters and which one will work on this Xmas wreath.

The reason I know this device takes 12 volts, is the exact item was sold on Ebay and I asked the seller and they said 12 volts.
The odd looking plug is typical for devices made outside USA so I'm told. I've cut the plug off, so I can try to find an adapter that will work. The 12volt DV 800 MA seems to work but maybe not 100%. Unless the device is damaged and the upper half won't light up.

The wire from the wreath was supposed to lug into a wall adapter and that is the part that was missing.
I've for a few adapters smaller than 12 volts (10, 9.5) with "larger" than 800ma. But if it needs 12 volts, then these should not work.
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Check at first your device. There should be Voltage, VDC (Voltage in direct current) or VAC (Voltage in Alternating Current), Current. VDC can be marked as -, VAC as ~.
You can't use VAC adapter when you need VDC an vice versa.
Maximal current from adapter should be more then need device.

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nickg5Author Commented:
well it lights up with the 12VDC 800 MA

so the 12VAC won't work, period....!
Yes, if it light, you need 12VDC, polarity seems to be correct. Latest check- Current or VA (Volts*Ampere, 20=12*1.67).
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☠ MASQ ☠Commented:
Match the voltage and then match or exceed the amperage needed - also check polarity with DC outputs usually there will be a symbol to show which lead is positive (particularly if there is a coaxial 'pin' plug).

20VA is the same as 20W (V x A)  it's the total power the adaptor can deliver.

Looks like you need an adaptor capable of delivering a higher current.  Don't go for somethiung with a higher voltage.
nickg5Author Commented:
The device came with the adapter orginally. I'm sure that adapter was marked with everything, input and output.
That part is missing and there is no marking on the back of the unit that says what it needs.
I know it takes 12 volts and inside is a small round fuse like part.

Will the 12 volt adapter with the 12volt "AC" output ruin it?

One of my 12 volt adapters is 12 VDC and the other is 12 VAC.

If the two wires from the AC output adapter are just reverse from a DC output adapter, I could cut the wires and hook them up opposite., but there is no markings to tell me which is which. There is a wire coming out of the adapter and it has two wires that can be separated and one is marked 18 guage, and usually the one that is marked is the hot wire. But it dead ends into a round plug. I'm not sure the polarity on the device needing the 12 volts.

If the unit is damaged inside, and that is why not all of it lights up, then this 800MA is enough.

If it is not damaged inside and still not lighting up properly, then the 800MA is not enough, and the only other one I have is this 12volt AC....to get 1670MA to the device.

Have you device some marks near plug-in? Have it any model?
nickg5Author Commented:
no marking at all. It orginally came with the adapter but the apdater and all it's input and output voltages-amps are missing.

I guess the question is:

Can an adapter 12 volts "AC" ruin a device that needs "DC".

The 12 volt DV 800MA adapter does work, but the top half of the 9 inch diameter sphere in the middle is not very lighted.
This may be because the 800MA is not enough.
This may be because the thing is partially defective and the 800MA is enough.

Damage is possible, it depends on scheme, but normally same AC voltage as DC do not damage device.
Both your reasons (Low adapter Current and device damage) are possible.
Can an adapter 12 volts "AC" ruin a device that needs "DC".

YES. it can.

The 12 volt DV (DC) 800MA adapter does work, but the top half of the 9 inch diameter sphere in the middle is not very lighted.
This may be because the 800MA is not enough.
This may be because the thing is partially defective and the 800MA is enough.

YES, and now you know it is 12VDC...so try / test it on your car battery.
If it now works then you just need a stronger 12VDC adapter... maybe 1.5-2.0A  

If the 12V rated device inside the damned lamp is incandescent bulb or properly designed circuitry, the 12V AC won't do any harm.

But yes, you would be better off trying it on your car battery before you start building a rectifier bridge (and a capacitor) for your second adapter.
nickg5Author Commented:
I only have the two 12 volt adapters.
The 12 volt DC 800MA lights it up.

If the 12 V "AC" will ruin it, I won't try it.

It has a 12 volt transformer inside and the bulb appears to be round fluorescent. The back can not be taken off without ruining it. I can see the 12 volt transformer.

Kent KellerCommented:
That little thing is the starter/ballast for the Florescent bulb.  Basically it has to jack up the voltage to get the florescent to come on at the beginning. ie FL bulbs need extra volts to come on and then settle back down to normal voltage if I understand it all correctly.

Go with the idea of wiring it directly to your car battery. That is the best test you could do at this point.
nickg5Author Commented:
not looking to test it.

need to know if the 12 volt AC adapter will ruin it.

If so, I'll stick with the 12 volt DC adapter.
Kent KellerCommented:
The test will help you figure that out. If it doesn't work with the car battery then it may require the AC. Odds of you ruining it by connecting a higher amp DC source is much less than the chance of ruining it with an AC adapter if it required DC.  That being said assuming there is no electronic stuff in it ie computer chips and the like then AC probably won't ruin it at the same voltage but may still not work well.  

Another option is to google images of fiber optic trees and see if you can find a match on a site that has the manual or specs or picture of the original transformer.  Or even the website of the store you bought it at.
Kent KellerCommented:
In my quick googling of Fiber Optic trees I saw lots of reference to needing more mA than you were providing.

Also I found this site that sells replacement parts for Fiber Optic trees.  All of the power supplies there were VAC so perhaps yours would be too.

nickg5Author Commented:
ok, thanks.
I gave the item to a relative with the 12 volt DC 800ma adapter.

An electrician suggested AC and DC are not interchangeable.

Not sure.

It lit up with the 800ma DC.
The new owner can experiment further.
nickg5Author Commented:
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