In many cases google is your friend when looking for something. Your requests lacks description of what you are actually transforming with your now faulty transformer.
Here is a page or two of searches for both 24 v to 12 v and 240 v to 12 v units.
I doubt it is a "transformer" more likely a switch mode power supply but unless the OP actually gives us full information on the unit we may as well gaze into a crystal ball.
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"I beseech you in the bowels of Christ think it possible you may be mistaken"
Oliver Cromwell, 3rd August 1650 - in a letter to the General Assembly of the Kirk of Scotland
Jayco used units called Setec at one stage, and prior to that I believe Centurion. It is likely yours is a similar type unit.
It would help if you know, or could find out, what unit was used in your van. There should be some markings or detail on the unit itself, or maybe there is some paperwork with the van. Come back with that info, and you may get some more helpful answers on what can be used to replace it, or where you can find the same unit if still available.
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Regards Ian
Chaos, mayhem, confusion. Good my job here is done
Jayco used units called Setec at one stage, and prior to that I believe Centurion. It is likely yours is a similar type unit.
It would help if you know, or could find out, what unit was used in your van. There should be some markings or detail on the unit itself, or maybe there is some paperwork with the van. Come back with that info, and you may get some more helpful answers on what can be used to replace it, or where you can find the same unit if still available.
Even a photograph would be of useful and give a clue.
Let's get the terminology correct for starters. People who know SFA about electronics call any black box in a van a "Transformer." Read through that link to see what they are about, when you understand them you will cease being one of the great unwashed who use the wrong term. Transformers produce AC power out of them, they are no good for charging batteries. Some of the vans built up to the early 2000s had them fitted to power the lighting in the vans. Gazal may have been one of the companies who used them. (it is also no good attempting to consult them regarding anything, they went belly up a couple of years after they built your van.)
Most of what you commonly find in caravans are power supplies or battery chargers. These produce well regulated DC power. The devices commonly used in the early 2000s were power supplies like those supplied by Hybralec, Centurion or Setec. These were used for charging batteries but were not very effective for the task. Around that time smart chargers were starting to appear like the Ctek and the Durst Smart Charger (details in the link below.)
Alan, if you can provide more details like some have asked for it would be a help to us. Pull the device out and look for anything printed on the case for any printing or numbers, this would assist those of us who have been around since the 1990s to identify it.
The other thing for us to know is, did/does it have a battery? Are you intending to eventually install a battery so you can camp off power for a night or three? At this stage it is possibly just academic to find out what you had. Let's just go forth and set you up for the future with updated equipment. If you don't wish to install a battery then install a 12 V power supply. Select one that is large enough to power all your lights and a few other 12 V devices like a car radio plus (laptop and phone chargers if they are the cigarette lighter type.) If you wish to spend a night or two camped beside the road whilst travelling between parks, you can put a changeover switch in so you have the choice to power your lights from the car battery or the power supply.
If you are intending to put a battery in the van, do it now. Select an AGM battery of 80 to 120 Ah size and a smart battery charger of around 15 to 25 A output. This will allow you to camp for several nights off power before having to head for a park to recharge the battery. If you eventually wish to spend longer off power you can add solar panels and a controller later down the track. At this stage, use the KISS principle (keep it simple stupid.) Do not overcapitalise your van at this stage, wait until you have sorted out your camping style. By the time you decide what you want you really want you may be looking for an updated van. Don't be stampeded by the lithium chorus, you will probably end up spending more than your old van is worth if you follow their directions.
After the first couple of smart answers he probably wont be back.
Then, just like Buzz Lightbulb, he needs to develop somewhat more personal resiliance - this is the internet and it isn't going to change just because you're a sensitive little poppet.
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"I beseech you in the bowels of Christ think it possible you may be mistaken"
Oliver Cromwell, 3rd August 1650 - in a letter to the General Assembly of the Kirk of Scotland
Plenty of people use internet forums for testing the development of AI software.
Almost 30 years past a friend wrote a rather good one he named Nigel Migraine which use to write AI poetry and post to the News Groups, most often it was hard to tell Nigel was not human - things have come a long way in 30 years....
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"I beseech you in the bowels of Christ think it possible you may be mistaken"
Oliver Cromwell, 3rd August 1650 - in a letter to the General Assembly of the Kirk of Scotland