Pull a power supply out of a computer and go to town! The most common computer power supplies (ATX form factor) provide several different DC voltages, such as +3v, -3v, +5v, -5v, +12v, and -12v. Mix and match between those specific wires or the common and you’ve got most of your onstage effects covered. For example, for our current show we’re using the +12v and -12v leads to power several 24v solenoid valves.
You can tie into the bundle of wires from the power supply directly, or install terminal strips or similar connections onto the power supply housing. I have no intention of providing instructions here, but a google search goes a long way.
Be safe. Computer power supplies make use of high capacity capacitors that will give you a dangerous amount of sizzle if you are not careful. Don’t electrocute yourself if you decide to take a power supply apart, cause it’s not only embarrassing, but very dangerous as well.
A few more thoughts, not all computer manufacturers use the same color code for the voltages, so be sure to verify with a multi-meter. Also, the power supply’s maximum wattage is usually provided on the label. Do some simple math and make sure you’ve got enough juice for your effect.
Now you’ve got a stock DC power supply that will provide most of the voltages you will need.