The task of a step down transformer is very simple; reduce the input electrical current voltage to lower levels. While it does change the current voltage it does not mean it will affect its amperage and this is actually something good. When we’re looking into a particular device electrical need, the main factor we must care for is the voltage. That because if you feed a certain device with a voltage higher than it was designed for the electricity will cause irreparable damage to the device circuits. That’s why a step down transformer is an important component in electronics, especially within AC adapters where there is a higher need for voltage regulation.
Differences between a Step down Transformer and a Voltage Regulator
A voltage regulator is an electrical device used to automatically regulate and maintain a constant voltage level. They can be considered a downgraded step down transformer. Depending on the design they can be used in either AC or DC systems. It can be a simple feed-forward design or also include negative loopback control loops but the output voltage can only be held constant. They can be found everywhere, to computer power supplies to automobile alternators and central power stations where it is used to control the output current voltage.
We can imagine a step down transformer as a whole system that will have lots of components to control and step down the current voltage, including a voltage regulator. It is not a component but a system itself and they may have one or more voltage regulators as well as rectifiers, transformers, inverters and other electronics components.
Why There Are no DC Step down Transformers
As you may already know, a Direct Current does not have a changing magnetic field; it operates in a single flow with a single polarity. That makes it impossible to create a magnetic force that’s able to accelerate electrons between two coils. It does generate a magnetic field on the second coil, but the magnetic field alone won’t make any electrons to flow on the coil, thus they won’t carry any current. This process is well illustrated by the Faraday’s law of induction; it describes that AC current is able to generate a changing magnetic field because the current creating the field is in constant change between its polarities, what do not happen with the DC current.
How is it Possible to Step down DC Current Voltages?
While it may not be possible to create a DC transformer we can still step down the voltage of a dc current with other methods. The most common methods used by different step down transformers are the Linear Mode, the Switched-Mode and the DC-AC-DC conversion.
Linear Conversion
The major drawback of this conversion method is that it can only output lower voltages from the input current. This method is also very inefficient because any spare power will cause it to dissipate heat equal to the difference of the output current and the voltage drop. The heating exposes the circuits and components to a higher degradation level and thus will need bigger and more expensive high-rated components, that’s why they are not used in large-drop high-current applications.
Switched-Mode Conversion
This is one of the most efficient methods of voltage conversion on DC current, having its efficiency range from 75% to 98%. The voltage level conversion is made by storing the input energy into a temporary storage and later releasing the energy at other voltage levels to the output. The temporary energy storage can be made through magnetic field storage components like inductors and transformer (for storage only) or electric storage components, a.k.a. capacitors. The cost of this conversion method can be higher to some extent; for this, new and cheaper advanced in-chip designs that are ready to use within electronic assemblies have come down with its high component costs.
DC to AC to DC Conversion
This is the easiest way to convert a high DC current voltage to lower levels. The title is pretty self explanatory and the process is simple as well. To accomplish the voltage conversion, the DC current will first have to be converted into AC current, that way it’s possible to use an AC transformer to regulate the voltage and later, by using a rectifier, the output current can be rectified back from AC to DC.
What to consider when choosing a Step down Converter
There are some things to take into consideration when you about to choose a voltage converter to make sure it will best suit your needs. Some factors like wattage rating and voltage range are critical things to look into, especially when dealing with delicate devices.
- Make sure the voltage range it operates matches the input current voltage. Many voltage converters are intended to operate in a large range, generally from 220 to 240 volts, but not any will accept ranges from 110 to 240 volts.
- Always check its watts capacity and take care into not using appliances with higher wattage rating than the step down voltage converter. A simple math can find out what’s the wattage rating of an appliance. Multiply the voltage by the amperage and your result is the wattage or Wh (watts per hour).
- Assess the load the step down transformer can manage. Most manufacturers will describe in the manual whether their voltage converter will handle high loads and/or accepts multiple appliances connected at once, but most of the cheap converters will only accept one device at a time.
- Make sure it works with a fuse, otherwise you might lose your step down converter if you run into an overload or an over current.
Step down transformers will vary in size depending on the application. Each one will have different features so you must keep an eye open for it. Always ensure you’re selecting the transformer that will meet your requirements on its watts capacity and output voltage levels.