A 12v transformer can be had as either AC voltage or DC voltage – or so people think. It is no wonder if this subject confuses people, because really, there is no such thing as a DC transformer. “But I have seen them for sale all over the place”, I hear you say. You may have, but the fact is that a transformer cannot, on its own, produce a DC voltage on its output – from the AC mains voltage on its input. What is advertised as a DC transformer, is actually a DC power supply. A power supply often contains a transformer – but not always. When it does, there will also be other electronics present, which perform the actual conversion from AC to DC. The transformer takes care of stepping the mains voltage down to 12v – and nothing more.
Now that we have cleared that up, which type should you buy then? The answer to that is “the right one”. What I mean is, to be able to find the right type of transformer or power supply for any application, you first need to be absolutely sure what your application requires. Put straight – if you have an electronic device which has lost its external power supply, take a good look in the manual or on the back of the device, to see what the power requirements are. It will be clearly stated whether you need AC or DC, what voltage (you are sometimes given an interval, like between 9-12v), how many miliamperes are needed, etc. If you need the transformer for low voltage lighting, You should first be clear on whether you are going to use AC or DC compatible bulbs. AC is the most common for incandescent and halogen bulbs, but DC versions can also be found. The advantage of AC is that bulbs are cheap and easy to find, while cable gauges can be kept smaller than for DC. DC bulbs, on the other hand, are more energy effective than the AC variety, so as you can see, there are trade-offs either way.
DC and AC voltages both have their relevancy for you – just remember to use the right kind for the job.
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Category: 12V Transformer