Many things related to electronics and electrical installations are a bit fuzzy to most people. We just want to plug in things, flick a switch, and… action! Sometimes though, we need to step up to the plate and learn a little, in order to move forward. 12v transformers are very commonly used components for applications like halogen lighting, battery chargers, shavers, etc. Many of us have been in the situation that a missing transformer or power supply was the only thing standing in the way of making some gadget work. Especially with the compact transformer equipped power supplies known as plugpacks or wall warts. Whenever I have moved house, they seem to be the first thing going missing and never to be found again. Luckily, they are rather cheap – but how do you know exactly which one to get? Read on.
Transformers are passive electronic components which transform an input voltage on its primary winding – to an output voltage on its secondary winding. Most commonly, the input voltage is whatever the local mains voltage is in your part of the world, where on the other hand, the secondary can range from below 1 volt to way above the mains voltage. The reason 12v transformers are so widespread, is probably because it is the next step over a 9v battery. 12v batteries tend to be quite bulky, as they are often used for automotive applications, so we might as well use a transformer.
12v lighting transformers are something many people are looking for. 12v lighting is in the category of what is called low voltage lighting, and is becoming popular for such uses as outdoor lighting, where it does a good job of accentuating the landscape, without lighting it up like a football field and using hundreds or thousands of watts in the process. A basic transformer for halogen bulbs is just the transformer and perhaps a thermal breaker to interrupt the circuit if it is overloaded from something pulling too much current.
If you are looking for a 12v dc transformer, you should know that really there is no such thing. A transformer cannot produce dc voltage all by itself. It is therefore often coupled with a rectification circuit to produce dc voltage, as often used in consumer electronics. A battery charger for instance must have a dc power supply, as batteries do not like ac voltage at all. The correct thing to call something that outputs a dc voltage, is a dc power supply – not a transformer. Hopefully this clears a few misunderstandings and makes it easier for you to find what you are looking for. Dc power supplies are also often equipped with fuses – often replaceable.
By the way – to get the right 12v transformer, remember to look at the power rating on both the transformer and the thing you want to power. They should either be a matching number of watts, or the power supply should be slightly larger than needed. Also make sure the “hot” lead and the ground lead are clearly marked. Otherwise you may accidentally connect them up wrong, possibly destroying your electrical application.
Find out more about picking the right 12v transformer or how to find 12v lighting transformers at 12vtransformer.com.