How to Choose a Power Supply

There are many great places to find a cheap power supply for your project. Different power supplies have different levels of efficiency and quality. It is important to consider these differences for your project. With some circuits a the voltage may not need to be exact for others it may. You will have to decide the level of power efficiency you desire. This article will help you choose a power supply for your project.

Instructions

1. Determine the type of power you will need for you project. Will you need to supply AC or DC power? Most projects require DC power even though many device can be plugged in directly into an AC outlet. The AC power is typically converted to DC power within the circuit or the AC power is simply used to charge a DC battery.

2. Find wall plugs also known as wall warts. These are the boxes that plug into the wall that are typically black in color. You may have a few laying around left over from an old phone, radio, or other small appliance. These units are a cheap way to supply AC or DC power from an AC outlet. Each wall plug contains a different AC or DC voltage with a different current rating. For example it may say 6 VDC @ 300 mA, this means the power supply will provide about 6 volts of DC power (full loaded) with a maximum current of 300 mA. Your project should never exceed the maximum current level. These easy to use devices are a cheap way to supply power, but can be wasteful of energy. Also, they can sometimes output a different voltage depending on the load of the circuit. Make sure you test the output voltage so you do not damage your project.

3. Choose an isolation transformer when you need more current and good efficiency. An isolation transformer will need a small circuit with a proper ground and fuse to transform the power from AC to DC. The downside of using this type of power supply arrangement is the size. Higher current power supplies can be quite large.

4. Choose a linear power supply for a smaller, more efficient power supply. The linear power supply uses a set of diodes to transform the power from AC to DC and capacitors to regulate the power level. This type of power supply can be very stable and efficient. On the negative side, linear power supplies are only good for a small current. Larger linear power supply current require a very large circuit.

5. Choose a switching power supply to provide one of the most stable, efficient power supplies. Switching power supplies are extremely stable under varying loads. Switching power supplies have been used for years in arcade games and other electronics, they are now very popular in computers. A high level of power and current is available in a relatively small size. The downside in choosing this type of power supply is they can be more expensive.

Tips & Warnings

• If you do not understand electronics or power, never attempt to create or modify a power supply.