If you are into do it yourself electronic projects, you will inevitably require a 5 volt power supply or 5 volt power regulator to run a microcontroller. Many people including myself have used an LM7805 integrated circuit to regulate a 9, 12 or greater supply voltage down to 5 volts. The LM7805 is a linear regulator which is cheap and easy to use. One issue with the LM7805 power regulator is that it can be electrically inefficient. If the voltage regulation source is from a high voltage (say 12 volts or higher) and the project is drawing a significant amount of current at 5 volts, the regulation creates and dissipates heat, a lot of heat. This can be a problem if the power source is from a battery, draining it quicker than necessary.
A switching power regulator has higher electrical efficiency. The result of using a switching regulator will be increased battery life. You can buy a little switching power regulator off of the internet for a small price. An even less expensive way to acquire one quickly is from a local "dollar" store. I think these stores are almost entirely stocked with inexpensive products from China. You may even have already purchased one of these regulators to charge your phone in your vehicle.
Refer to this website for a better and simpler explanation of linear vs switching regulators:
I have purchased an inexpensive cigarette lighter plug 5 volt regulator for my car. It didn't work with my Apple products so I decided to use it for a 5 volt power regulator.
Step 1: Disassembling the Regulator
This device was easy to pry open by inserting a flat end screw driver into the opening where the side prongs flare out. The housing literally popped open with enough force by twisting the screw driver. The regulator housing was simple to disassemble and reassemble too. The ground leads or flares as I call them were desoldered from the device. I left the original usb pins in place because there were tiny surface mount components very close to the usb pins. I thought I would desolder these small surface mount components by accident if I tried to remove the usb pins. Maybe for your useage of this device you may want to keep the usb connector.
Step 2: Testing the Output
I tested the output of the regulator (with 12 volts input). One of the end pin outputs measured 5.1 volts. The two center pins measured 3 volts. These pins may be useful for lower voltage requirements. The other side of the output pins is of course, ground. I don't know how much current this regulator can supply but I think a reasonable guess would be 500 to 1000 milliAmps. There is no written information on the regulator I used. There may have been on the original packaging. The second (orange ) regulator I pictured does have an electrical rating of 1 amp at 5 volts with an input voltage of as high as 24 volts.
Step 3: Finishing the Regulator
I soldered on the supply voltage wires (red and black)(in my case the input voltage is 12 volts). I only wanted 5 volts (not 3 volts) so I soldered the blue and orange wires to the 5 volt and ground pins. The wires and connectors were removed from old electronic parts I have.
Heat shrink was used to protect the exposed wires and give the wired connections some strength. A good practice is to use different sized or configuration of wired connectors. This will prevent any damage to the regulator because the input and output voltages can't get mixed up.
I needed a way of insulating this whole device so I used a large diameter heat shrink. I can now use this efficient regulator to supply 5 volts to an arduino project run from a small 12 volt lead acid battery.