Powering Circuits

Most of the circuits that we'll be building will only require a 5 or 6 volt DC power source. There are a few different options for this:

6 volt lantern battery
A simple, low cost solution.

Battery Pack (using 4 AA batteries)
A little more compact than the lantern battery, they also give a professional look to your circuits. You can find some nice units with a built in on-off switch, like the SBH-341AS at DigiKey, for just over a dollar.

DC Power Supply
These power supplies are used by most serious designers of electronics. They convert 120 volts AC to a safe and useable DC voltage. You can get fixed voltages power sources, which may deliver 2 or 3 different volatage levels (5-12V is common), or variable power supplies, which allow you to dial in the level you want. The good news is they never run out of batteries and are very stable. The bad news is that they're relatively expensive -- you can expect to spend $30 for a cheap one, and can spend hundreds.