Transformer Theory

• A transformer is designed to change or transform an input voltage to a different output voltage. A simple transformer consists of two sets of wires wound around opposite sides of a ferromagnetic core shaped like a square donut. When you apply an alternating current (AC) voltage source to the primary or input, you get an AC voltage on the secondary or output that is proportional to the number of windings on the primary and the secondary.
  
  

Low-Voltage Transformers

• Most low-voltage or "step-down" transformers are typically designed to transform standard household voltages of 120-volts AC to lower voltages of 24-volts AC or less. This is accomplished by having five times as many windings on the primary as the secondary, thus "stepping down" the secondary voltage to one-fifth the primary voltage.
  
  

Low Voltage in the Home

• Low-voltage transformers allow us to use lower-voltage devices for household applications without high-voltage requirements. They are also less expensive to manufacture and are easily maintained by the average homeowner. This translates into a cost savings for the homeowner due to lower energy costs and reduced maintenance costs.
  
  

Low-Voltage Home Applications

• Low-voltage transformers are at the heart of most low-voltage devices in the home. This includes such things as doorbells and chimes, cell-phone chargers, movable track lighting, electric tool chargers, garden and lawn lighting devices, etc. In addition to the economics, low-voltage devices are much safer, due to the reduced potential for shocks. This makes them popular with do-it-yourself homeowners who would prefer to buy and install a low-voltage device. At the same time, they are more popular with the manufacturers since there is no need for installation personnel.
  
  

Low-Voltage Industrial Applications

• The low-voltage transformer plays a critical role in hospital halogen applications such as emergency rooms and surgical suites. In the machine tool field, low-voltage halogen lighting has become required for visibility on high-precision work. In recent years, the light-emitting diode (LED) has begun to make serious inroads to replace the halogen light. Even the airline industry is looking closely at LED-based lighting. The search, of course, is for better performance at lower cost and less energy consumption--all areas where low-voltage transformers play a part.