The Auto Option
While the term auto transformer might immediately make you think automatic transformer, the name actually comes from the fact that this transformer model has only a singular winding. Other electric transformer models would be constructed with a primary as well as a secondary winding. In the auto transformer, the coil is able to have one side of the coil operate as the primary winding, while the other side would operate as the secondary winding. In this way the one coil is able to behave in the same manner that the two coils would work in other models. Which side will function as the primary and which as the secondary will depend directly on which side is connected to the load and which is connected to the power supply. In the end three connections at least must be made. These connections will help draw the voltage to allow the transformer to function in the correct manner.
While it may seem that the auto transformer is the perfect substitute for the traditional transformer, there are some things that must be kept in mind. Auto transformers, while a great option, do not have the same capabilities as a traditional model. One issue is that in an electric transformer, there is an isolation provided by the fact that the windings are separate. Since, in auto transformers, the windings are the same coil, this isolation method does not exist. What this can result in is the isolation that is provided in the auto transformer could fail. This would trigger united voltage in the winding, in other words, the input levels would be the same as the output levels. This could be a problem where multiple circuits are involved. So, before selecting the transformer for your application, make sure to talk to an industry expert. They can help make sure that your decision is the right one!