Now that I have 2 Arduinos I need something to power them. Easiest is to power the Arduino with the USB cable that you also use to upload a sketch. If you’re going to use it without a pc you will need another solution. One solution is to buy connectors that fit on 9V 6LR61 batteries on one side and have a 2.1mm plug on the other.
To power the Arduino from a wall socket I bought an adapter. More information on what kind of adapter you need can be found on the Arduino website. At the local electronics shop I found a regulated universal voltage adapter.
It has a switch to set the voltage from 1,5 to 12V and comes with a bunch of different connectors that can be easily changed, the Arduino needs a 2.1mm plug. At 9V it can output 1100mA and at 12V 1000mA. More then enough juice to power an Arduino and some leds and sensors.
The uber cheap solution to power your Arduino is to simply buy an USB charger. One of these cheap Chinese made adapters came with my made in China Android smartphone. These things are really cheap, but not the most reliable. The one that originally came with my smartphone died after a couple of days. I ordered a couple of new ones on ebay, you can easily find these for a couple of euro’s shipping included. The ones I have give 5,4V and can deliver 500mA. That should be enough to power an Arduino.
For things that need a lot of amps like for example a stepper motor you need to provide a separate power supply direct to the motor or driver board. Since the I/O pins of an Arduino Uno can only switch 40mA. Luckily I still have a big old lab power supply, cost me quite a bit of money a long time ago and I haven’t used it in years. The voltage can be regulated between 3 and 15V and it can provide 25A. It’s an excellent device to release smoke from electronic components 🙂 I do my best to not use this function to often.