03 August 2012

Wiring DIY - Part 05

Slide Switches

Slide switch types are very limited. An inner plate slides over two rails establishing contact with a couple of lugs (per pole). The most common types are SPDT and DPDT. They work exactly the same as we were describing on Part 03. DPDTs can be with center on or center off. In the case of center off, there is no contact in the middle position. In the case of center off, we have a DPDT on/on/on Type 1 (as shown in Part 03).

Gibson' Swiftcraft type switch

This is a tricky DPDT on/on/on switch.
The two poles are the two central lugs. When the handle is on the middle, the 4 lugs are in contact but, in pairs.
When the handle is at right, the 2 lefty lugs are in contact and, when the handle is at left, the 2 righty lugs are in contact.

This picture shows the three positions, looking at the bottom of the switch.

The upper lug on this picture is the grounding spot for this switch.
So, usually the two central positions (poles) are soldered together (to the output) and, each extreme is usually linked to one pickup (or the volume pot that controls that pickup).

Fender' S-1 switch

This is a push/push pot that comes with a wafer with 4 poles and 2 throws by pole, that is, a 4PDT on/on switch. Every time that you push the button, the switch changes the throw.
Everything that you do with an S-1 switch, can be done with a mini-toggle 4PDT on/on switch but, a toggle 4PDT will require additional space in your electronics cavity and, will need to route some other hole in your pickguard or guitar body. The nice thing of the S-1 is that is hidden under one of the pots and, it's small enough to be fit guitar's cavity.
This switch is usually seen in Deluxe or very special models, where a lot of alternative combinations are being offered stock.

This is what happens on this switch (seen from the bottom):

The lugs or contacts of this switch aren't arranged on columns or rows but, they work under same principles of any 4PDT on/on switch.

Rotary Switches

Rotary switches  have a lot of variety, they are multi-pole and multi-throw. Usually, way more throws than poles in the same switch. The most usual rotary switches that you will find in a guitar will have 2 or 4 poles.
Usually, for each pair of poles, those poles and their corresponding throws are distributed in a circular wafer. So, a double pole rotary switch will have a wafer and, a four poles rotary switch will have two wafers.
Usually, it makes no sense to use a rotary switch with less than 6 throws, since we already have blade switches that cover up to 4 poles and 5 throws (as the super switch) but, sometimes, there is not room enough in our cavity to mount a blade switch. In those cases, one pot can be sacrificed and a rotary switch can be installed in its place, instead.

Some PRS models are using a rotary switch to select their pickups' combinations. Some Gibson's include the Varitone mod, that works with the help of a rotary switch. There are some other uses, for sure.

Look at this picture, showing some samples of Rotary Switches, seen from the bottom:

The upper left one is a DP4T rotary switch, the poles are those red and dark blue dots. Usually, poles are placed on the center, if the switch has just a wafer.
The upper right one is a DP6T switch.
The lower left one is a 4P3T switch, a rare case where there are more poles than throws.
The lower right one is a 4P6T, with two wafers. The occult wafer corresponds to the lugs that are shown peripherally. Note that the poles of the lower wafer aren't on the center (lugs labeled as C).

Rotary switches are the kind of switches that have more diversity so, if you are looking for a certain combination of poles and throws, it would exist a rotary switch that has it.
The drawback is that every rotary switch is being implemented in a different way. Where are poles placed and, to determine which position corresponds to each throw isn't always easy so, be sure to read their specifications to have a clear picture on how they work. What is common is that for each turn (throw or position) every common (pole) that the switch has, will be connected to the lug that corresponds to such a position. If the switch have 6 poles, and we are switching to position 1, every one of the six poles will enter in contact with its lug corresponding to position 1.

At this point, we reviewed the main electronics components that we can find in a guitar so, we can start describing the different ways to connect pickups and which sound we can obtain for each way. This will be described in next Part.

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