Six Essential Circuits

2013-11-20

The Megalottacombo wiring scheme is complex if you just sit down with the final diagram. But it’s not as complex if we start by looking at the basic building block of the diagram: a single humbucker pickup feeding into a single switch.

If you understand how the switch is creating these six essential circuits, it will make it a lot easier to understand what comes next.

The Six Essential Circuits

On the previous page, I counted six essential ways to wire a single humbucker pickup which are fundamental and interesting. Those six ways are presented here again, by themselves:

There are additional ways to wire a humbucker, but on the previous page I eliminated them as either not useful enough, or created by other means.

The most common way to wire a humbucker is “both coils, in series, normal phase”. If you have a humbucker with only two wires, it is probably connected this way.

What I wanted to do is create a way to have all six of these fundamental connections using a single switch. That process is described below.

Which Switch?

Diagram view of a 4-pole 6-position rotary switch
There are 4 layers of switching, each layer has 6 positions

The excercise was this: what kind of switch would let me have four wires from the humbucker as input, and two wires (pos/neg) as output, and somehow let me create all the combinations above? There is the Fender Super Switch (4-pole, 5-position). Is there something else that does six positions?

After some study, the answer was a 4-pole 6-position rotary switch. One pole for each of the four wires coming from the humbucker. Six positions for the six essential circuits outlined above.

Next question: Is anybody making a switch like this? I found out that Electroswitch makes many rotary switches. I liked their C1 series, which are their “smallest enclosed rotary switch”. Small, good. Enclosed, good.

I got the C1D0406N, and it fits the bill. Small enough for a guitar, high quality, good materials, enclosed, long life, and made in the USA.

Single Pickup - Rotary Switch Wiring

Single pickup wiring
Click for PDF

How does the rotary switch allow us to connect the humbucker pickup in six different ways? This schematic diagram shows how.

At the top of the diagram there is a humbucker pickup with four-conducter wiring. The pickup wires are marked “S” for start of coil, and “F” for finish of coil. Each conductor from the pickup is wired to a different pole of the switch.

At the bottom of the diagram, the output of the circuit is two wires, shown as positive and negative.

What happens in the middle of the diagram is the 4-pole 6-position rotary switch combines the four humbucker wires in different ways: this coil, that coil, both in series, and so on.

This schematic is kind of a mess of wires hopping over each other. To make sense of the diagram, it helps to trace the paths with color, which I do in the next section.

The illustrations on this page are also available as a PDF, where they are a little sharper and clearer. Click the image for the PDF.

Single Pickup Animation

Single pickup animation

The black and white, static schematic diagram is a little confusing with its jumble of crossing wires. To make sense of it, it helps to use colors to trace the parts that are active at any one time.

I have gone ahead and traced out each circuit, in color, for the six positions of the switch. And then I assembled them into an animation to save space.

Note: The electricity does not actually change color as it moves around the circuit.  :-P  The colors are just to assist in tracking the role of each connection.