You may well believe, particularly those of you who are new to the craft of audio equipment design, that so long as the voltage need is met and current ratings are correctly designed, that any power transformer will work adequately. This, however, is far from the case.
What do transformers do?
In order to ensure your power transformers function adequately, it is first necessary to understand exactly how they work. In essence, a transformer is an instrument which works by converting an AC current to a varying magnetic field, before returning back to AC.
What are the different types of transformers?
El-core is the most common form of transformer. Although it is certainly the least expensive form of transformer, and therefore the most common type, it is also the worst due to its stray flux.
The toroidal transformer is often used in audio equipment catering to the high-end market. Circular in shape, the toroidal transformer differs from the EI-core in that rather than consisting of laminated stacks, it is made from a strip of metal wound around a core.
Due to the unsymmetrical winding of the device, they still often leak their magnetic fields. However, because of the small size and efficiency of toroidal transformers, they are favoured, but only amongst those who can afford them. At any level below 500W, they prove to be far more expensive. As reported by the BBC, energy costs have hit a five year low, but it is nonetheless still something to be conscious of.
The R core transformer is the most recently developed of the transformers on this list, and it has the potential to become the most popular transformer available. It works as well as the toroidal but is currently unavailable in the West. However, when it becomes available in the USA and supplies increase, the price should most likely drop.
Which one should you use?
When designing and building a quality piece of equipment, it is always necessary to carefully consider your choice of parts, just as some electricians in Kenya have done, as reported by AllAfrica.com.
Of course, there are differences between both the EI-core and the toroidal type of transformer. If cost is not an option then a toroidal unit is your best bet. However, in most circumstances EI-core will be more than suitable.