Transformers plug imto ac outlets is the 12 volt output ac or dc?

First its not a Whistler product, its a Fuzzbuster.. Yes, if the AC adapter is 12 volts DC output and is at least 500mA then it will be fine.

If you are talking about low voltage light transformers, then answer is probably NO... but you could try it and see if it works... but I am almost certain that both transformers will probably burn out.
Output is 12 Volt AC... the transformer coils will probably burn out because the waveform from each transformer cannot be guaranteed to be the same.... even if both transformers are seemingly identical and plugged into same outlet.

For additional information, read transformer installation tips on following page.
http://waterheatertimer.org/Malibu-power-pack-stopped-working.html#install

Power company transformers can be wired together in specific ways to produce 3-phase waveform, but these transformers are specifically engineered for the task. And the transformers do not combine the output (as you would be doing with yard transformer), instead each power company transformer produces 1 leg of power in a 3-leg power supply.
http://waterheatertimer.org/What-is-3-phase-electric.html#transformer

Gene

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If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Look at adapter, see what output is supposed to be- maybe 12 volts DC? Find a multimeter that will measure DC voltage, and see if the output plug has that across the connector. If you have an ordinary power cord without an adapter, it will have 120 volts AC like any other cord, which you can also measure on AC scale, but be careful as you can get a dangerous shock, just like you can from an ordinary household outlet.
Note: AC voltage may vary by country.

Output is 12Volts AC
http://waterheatertimer.org/Malibu-power-pack-stopped-working.html

Low voltage bulbs are labeled AC.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

If you light is charging when you use the 12v automotive charger but not when you use your AC power transformer, my thought is that you might have a problem with your AC charger, not with the light itself. I have AC/DC transformers from the 1970s that still work fine, but I have had numerous modern AC/DC transformers burn out on me in recent years.

One easy test is to use a multimeter to measure the output voltage of your wall charger. Place one test lead on each of the charging terminals (i.e., one inside the barrel and one outside the barrel, if you have a standard coaxial charging port) and check the DC reading. If it's zero--or anything less than 12 volts, actually--the charger isn't working correctly. The problem may be a torn or cut wire or something actually inside the transformer.

Replacement chargers can be found at Radio Shack and other stores. You may also be able to score a cheap replacement at a "dollar plus" store or even at a second-hand shop. Make sure that the terminal polarity is correct on your replacement charger or else you'll fry the batteries in your light.

Good luck!

in a word no!,,,,it cannot and you may blow it up if you hook it up to the 115ac volt supply,,,in side it there is a switch mode power transistor,,that bumps up the 12 volts to 115 volts it only works the one way,,that is 12 volts dc in and 115 volts ac out,,,,

What is the Name Brand of lantern you have?

you inverter was not fully charged because it requires a 110/220 v ac as specified in the manual; to charge it so it is impossible for the aircraft 15vdc to charge it

THE ANSWER TO MY QUESTION WAS FOUND OUT BY MYSELF BY VISITING A REPAIR / SERVICE DEPARTMENT AND MAKING ENQUIRIES CONCERNING THE DC OUTPUT OF THE AC ADAPTER ASSOCIATED WITH THE WESTERN DIGITAL, MY BOOK 250GB USB. tHE VOLTAGES ARE THESE. : - AC INPUT = 100 - 240 VOLTS 50/60 HZ
DC OUTPUT = 12 VOLTS ( REGULATED ) 2 - 0 A
CENTER PIN OF 12 VOLT DC INPUT PLUG IS " POSITIVE "

THANK YOU FOR THE SPACE TO ASK MY QUESTION.

Model HER-48-12010
P/N: 68300021-0013
AC Input
DC Output