Transformers vs. Power Supplies

Often customers confuse transformers and power supplies when they are searching for one or the other. These two technologies are related, but are completely different in their applications. This post will look at the similarities and differences and help you decide if you are in need of a transformer or power supply and the options available to you.


These devices typically have two modes and a function that all apply to alternating current applications. They are used for stepping up AC voltage, stepping down AC voltage, and isolating high voltage from low voltage in either mode. In the simplest terms, a transformer is a pair of special inductors coiled around an electromagnet. The ratio of how many turns in the inductive coil on one side compared to the other side determines the mode of step up versus step down. If there are more turns on the higher voltage side and fewer coils on the other, the transformer is acting in step-down mode.
On the contrary, if the lower voltage side has less turns and the other side has more turns, the transformer is acting in step-up mode.
The most important detail about transformers is everything is in terms of AC voltage and there typically aren’t ready made connectors for this as this technology is USED in a power supply design. Here are some photos of transformers we carry:



In short, transformers do not convert AC to DC.

Power Supplies / AC to DC Converters

There are several types of technologies for converting AC power to DC power. Here are the basic steps for producing this effect (this may vary based on technology, but the ideas still apply):

  1. AC Voltage is stepped down to a safe level using a transformer or similar technology.
  2. The reduced voltage is then passed through a full wave rectifier to produce a positive supply that is still going between 0 Volts and the stepped voltage minus the average forward voltage of the rectifier.
  3. The bouncing power is not stable for most applications, so this must be regulated.
    1. Regulation often changes based on technology more than the rectification and transformation, the general first step is to add a capacitor to reduce the ripple current to a more steady line.
    2. After the right capacitor is chosen, there is still too much ripple in most cases. Further regulation design is implemented to get the output to the designed output voltage at nearly DC levels with minimal ripple as possible. This design will change based on the type of power supply.

Power supplies and converters are more process based and convert AC to DC through use of multiple parts, including transformers at times. So technically, these devices may have transformers, but are not transformers by nature of operation. Here are some photos of supplies and converters that we have for example: