Arduino Not Working as Intended when using barrel jack I am using an Arduino to control some mechanical components in a project I have. It controls a motor, two servos, a valve, and a compressor. When plugged into the computer, everything works fine and perfectly. However, when I power it through the barrel jack using our power supply, some weird things happen. First of all, our servos, which are powered through the Arduino, stop working. All the other components work except for them. Secondly, at the end of the code we have a 5 second delay. Using the computer it works fine. When powered with our supply the delay doesn't seem to happen at all. Any ideas?
i agree with majenko, maybe you know how to fix it but if you do not know here is a site with good information to make you're own  5 volt Regulated source.

http://www.rakeshmondal.info/IC-7805-Voltage-Regulator

sorry for my bad english and good luck. :D