Alexplorer's Axe Hacks: Switches

Switches

Like potentiometers, this class of components also regulates the flow of an electric signal, just in an "all or nothing" matter. Also, some of the more complicated varieties of switches can be viewed more as routers than simple open/closed doors. That is, a signal runs from a source to one of several possible destinations.

Some important terms

Common. This is the lug that is connected to the incoming wire (or possibly the out-going wire, depending on the circuit). From the common lug, the signal goes in one of several directions. For example, the common lug of a pickup selector switch would run to the output while the other lugs were connected to the individual pickups.

Pole. Many switches have independent circuits. That is, they do not cross over to one another unless you actually wire them to do so. The number poles tells you how many circuits. Thus, a switch described as having a "double pole" would have two parts.

Throw. This refers to the number of possible connections a switch makes to the common. For example, a simple on/off switch would be a "single throw," whereas a Les Paul-type pickup selector would be termed a "double throw" because it switches between two pickups (It can also select both at the same time, but there is no nomenclature for this to my knowledge).

Pickup Selector Switches

First three: Various 5-way switches found in Stratocasters and similar guitars. All of these work exactly the same, although the arrangement of the lugs may vary (e.g., 8 in a row vs. 4 per side).

Lower Right: 3-way toggle, usually found in Les Paul and other Gibson guitars.

Toggle switches

These are very similar to the switching portion of push-pull pots, although they can commonly be found in a number of variations:

SPST - This is the most basic switch, and can really only be used to turn a portion of a circuit on or off.

SPDT - Toggles between two portions of a circuit, such as, say, two pickups.

DPDT: ON/ON - Similar to the above, but has two independent portions, although these can be wired together for additional purposes, as with a phase switch. This is what is found on every push-pull pot I have used thus far.

DPDT: ON/ON/ON - This switch may be used as a series/parallel switch with the middle position providing a coil tap as well, if used with a humbucker. These are somewhat more difficult to find due to their limited application (i.e., a basic ON/ON is adequate for most purposes).

DPDT: ON/OFF/ON - Similar to the above, although with a "silent" option in the center position, preventing the passage of any signal. These are very rare. An example application is a Tone Switch on many Gretsch guitars.

But...

Note that a more sophisticated switch can often be used as a simpler switch. For example, by using a pair of lugs on one "throw" of a DPDT switch, one can put these to work as a SPST switch. It might save you some time to know that you already have all the part you need for a project.

Rotary switches

These come in a variety of combinations. The number of positions is the number of possible combinations you can select among. Depending on what you are wiring, the number of poles is the number of things which can be attached. This isn't true, strictly speaking. The 5-way pickup selector on a Fender Strat is a 5 position, 2 pole switch, but you can hook 3 pickups to it, although they are all connected in parallel and in phase with one another. However, to achieve the maximum number of possible combinations, you really need more poles (at least equal to the number of coils on the guitar) or you have to include other switches to accomplish what you can't using the rotary alone. More specific possibilities elsewhere on this site.

Incidentally, although I describe their application here for switching between pickups, simpler rotary switches may also be employed for mods such as the varitone.

A mod for this mod: I found many rotary switches to be difficult to turn, but this can be corrected by applying a Dremel to the "bumps" to make it easier to switch between positions. Just something to consider.

side view

bottom view

If you notice any parts I left off this little primer, please email me.

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