The Basics of Switches

If you have ever installed a set of cold cathodes, or other special lighting gadgetry, then you most likely have been presented with an optional switch to install along with it to allow you to turn the device off and on instead of it staying on as long as the PC is on. I'm sure there people new to this sort of installation out there so here is a simple guide for hooking up a few types of switches you may encounter while tricking out your own PC with special electronics and/or lighting/cooling devices.

Why bother installing a switch?

The answer to that is really simple... control. A switch allows you to be in control of the state of activity of a component; whether that means a simple off or on state or something that will let you choose a setting among more than just two choices. For a device as simple as a cold cathode you may think, "Why even both with hooking up a switch when I can just let my lighting bling 24/7?" (or while the PC is on).

There times when the glare of an uber-lit PC next to you is not a desirable thing... like when gaming at a LAN party in tournament? When playing in total darkness for gaming ambiance? How about if you have to sleep in the same room with your PC? Plus, lighting fixtures all have a lifespan of use. When you turn off your lighting occasionally, and/or when you go to sleep at night, you are extending the life of that product's usefulness. That way the bling is there when you want it there and not in the way other times.

Then there is, of course, the matter of safety. I have seen first-hand a cold cathode burst into flames and melt it's housing. A switch allowed me to immediately cut juice to the inverter for that cathode and may have prevented serious damage to my other PC components.

Switch Terminology

Several terms are used to describe a switch and some other "need to know" terms:

- Pole - The number of switch contact spots.
- Throw - The number of conducting positions (single or double).
- Way - The number of conducting positions (three or more).
- Momentary - The switch returns to its original position when released. A PC Reset switch is a momentary switch.
- Open - The "off" position (contacts not conducting).
- Closed - The "on" position (contacts conducting; there may be several on positions).
- (+) Positive - The pole that connects to the live current source (usually via the various 5V [usually red wired] or 12V [usually yellow wired] contacts provided by the PC motherboard and/or PSU). Often marked with a "+" symbol, a small triangle or is labeled as pole #1.
- (-) Negative (Ground) - The pole that is the ground connection. Usually marked with a "-" symbol.
- Source, Trigger, Etc. - The pole that a signal/current is sent to when in a particular position. The pole will be labeled differently on various devices. Check it's documentation when available. When not available, simply eliminate the other poles by finding the ones marked with a + or -. If you only find one or the other, then the pole furthest from it is usually the opposite. The pole in the middle will normally be the trigger.