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DPDT Switch


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Hi Bio hazard.

this is how it goes, iirc:


    Ia Ib    Top row

   [Ic Id]   Middle

    Ie If     Bottom 

Ok, the I is the pin, the letter afterwards is MY designation. others will designate other wise.

the middle ones (Ic & Id) are boxed in because in effect, they are always on.

Anyway, with the switch up, the signal passes in through Ic, an is then routed to Ia, where it is then sent to an effect for example, then it routes through Ib to Id.

If the switch is down, it still goes in through Ic, and out through Id, but is routed through Ie and If respectively.

Its not to clear in the above diagram, but i will find a picture (or draw one) later if you want!


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That link I posted has diagrams including an example of a DPDT in action. Well, DPDTs are really the on-on variety... but when you look around you'll see on-off-on and on-on-on also called DPDTs, they're really DP3T :D.

Using a simple example of a pickup selector for 2 humbuckers, an on-on-on switch would provide the normal operation that your probably used to (bridge-both-neck.) An on-on would be bridge-neck and an on-off-on would be bridge-none-neck.

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Hi, i'm needing some help with a DPDT switch. They have two rows of three legs. So thats siz in total. How are the legs of the switch connected? Could anyone give me information on this please. Thanks.

you ever see those big electric switches on the wall in horror movies, that dr frankenstien throws to active his monster, or that the warden throws to fire up the electric chair? they have two upper poles, two poles in the middle connected to the swiveling U-bracket with the handle, and two bottom poles.

when dr frankenstein throws the switch, it breaks the connection of each middle pole to its corresponding top pole, and connects each of those middles to the corresponding bottom pole. that's on/on. if the good doctor stopped in the middle of throwing the switch, and the middle poles weren't connected to anything, that's on/off/on.

and on/on/on is if he only threw one half of the switch down, so in the middle position one of the top poles is connected to middle and one of the bottom ones is. there's usually a notch in the switch that specifies which sides are active in the middle "half on" position, since if you think about it both possible orientations of the switch are not the same.



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Setting up a DPDT depends on what kind of output options you would like. The most useful application is for changing distribution of signal from 4 wire humbucker pickups. You can wire them up basically for switching a pickup on or off, or you can wire them up for series/parallel, series/split/parallel or phasing your humbuckers. I have a DPDT installed on my strat for splitting the Seymour Duncan Hotstack (single coil size "stacked" humbucker) I have installed in the bridge position. In conjunction with the main pickup selector switch I now have more output options. Although both DPDT positions are technically always "on" I just call one side OFF = SC (single coil mode) and the other ON = HB (humbucker).

Selector switch position | DPDT position | Output

----------4-------------------|-------OFF-------|middle SC & bridge SC

----------4-------------------|-------ON--------|middle SC & bridge HB

----------5-------------------|-------OFF-------|bridge SC

----------5-------------------|-------ON--------|bridge HB

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I don't think it's been answered and I actually had a pain finding the information myself a while ago...Here's how it usually is...


1 2

3 4

5 6

this is basically 2 normal SPDT switches stuck together...

up position 3 is connected to 1 and 4 connected to 2

down position 3 is connected to 5 and 4 connected to 6

3 and 4 aren't connected...


same as before but with an off position in the middle


This is probably simple but it took me a while to figure out

Up 1 -3 , 2-4

down 3-5, 4-6

Mid 1-3 4-6 or also 3-5 2-4 (I don't know which is more common...I guess it doesn't matter)

I did find an animated picture of the On-On-On....I just can't figure out where it was...

Scott had a pretty good explanation...the on-on-on is the only one in wiring diagrams that ever messes me up...

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Ummm....Are you sure on that???

don't you have to bridge the pins to get that to happen like you have in that diagram????

actually the diagram you have would mean the switch would have no effect other than making the electricity change it's mind on which path to the same destination to take....

Maybe I missed something but for the time being I wouldn't go by that diagram

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This circuit has one push pull DPDT tone On-On Switch

and a gibson 3 way


This is a schematic done in paint...

I'm not sure on the tone control symbol...it's been years since I've used them properly...The gibson switch I've seen drawn elsewhere like this and is the closest representation of how it works that I can find

But in any case...this is how it's wired...hopefully I didn't mess up


For anyone that hasn't seen schematics...

The curly lines on the left are inductors...or coils...the pickups basically...the zig-zaggy guys on the right are the knobs...(variable resistors or pots) the gap below the tone is a capacitor...the out is the output jack...

The gibson switch either connects both or disconnects one or the other...we'll assume both are connected for this

So now we're aquainted with all but the DPDT switch...

(and for those that know schematics...I know this is a total mess...I'm soo sorry...if I wasn't so tired I'd clean it up)

For this you pull for coil tapping on the outer coils of both pickups...the picture has the pot upside down...so it might trick you...like it did me...so pretend my switch is upside down as well so I don't have to fix it

A DPDT is basically 2 switches together...and that's why that is the symbol for it on the schematic....

the input for the first switch is terminal 3 and the second terminal 4

in the pushed position (up on my diagram)....it acts like the switch isn't there....actually it basically isn't...it is an open circuit...output terminals 1 and 2 are selected...nothing is connected to them so it acts like a normal humbucker...

When it is pulled (down in the diagram) This is when the cool stuff happens....

The input for the first switch is in between the 2 coils the output for terminal 5 goes to ground....

the input of the second switch is the start of the top coil of the Second humbucker...the output is the middle...

This does look weird at first but I'll explain where this goes...

the current for the first PU travels through the first coil and before it reaches the second it finds a shortcut to ground (saves having to go through a mile of pickup coil...I don't blame it) so it skips the second one...

The Second humbucker is a little different...the current never reaches the top coil...it goes from the selector switch straight to the second one....starting from the middle...again...shorter route to ground...

Anyway....Now you know how DPDT switches work and coil taps....


I screwed up on the pic....not anything that affects the circuit operation...but if you number the terminals in the picture

2 1

4 3

6 5

it works ok....

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Ummm....Are you sure on that???

don't you have to bridge the pins to get that to happen like you have in that diagram????

you're right -- Strage Fruit's diagram is not completely correct. the two swoopy red arrows connecting the top and bottom poles are not connections that a DPDT switch will make, unless you did bridge the pins with a wire jumper.

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Ok, maybe i didnt explain properly, yes, if you want it to follow the lines, you have to put in a jumper. I personally put a jumper on the bottom pair and then use the top pair as the send and recieve signals from the effect unit. Sorry for any confusion!

BTW, with it setup as i said above, ie one pair send and receive, and the other a jumper, it is a complete signal bypass.


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That Diagram is right only if you bridge the two oute pins.

A simple way to look at a dpdt is to understand a spdt

One row of three lugs.

The middle lug is always on, and the outer lugs are on when the switch is pointed to them.

A DPDT is simply two of these. They are seperate circuits, controled by the same mechanical lever.

To make and on/off switch, you need the hot from the device going to the middle lug. Then one lug to connect the rest of your circuit(on) and then the other lug to ground(off)

This would leave one side of the switch completely untouched, the other side could be used to turn an led on and off.

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Well...With a triple pole double throw...it's basically the same with another row...

1 2 3

4 5 6

7 8 9

the middle would of course be the Live terminals....

So you'd bridge 1 and 2

4 would come from the pickups...5 would be the output

and 7 would be effects in and 8 effects out...that is the same as the DPDT

this just adds another switch to the package...you'd wire it like any battery switch...so it's open in the bypassed position (leave terminal 3 unhooked) and have it so that it completes it when the effect is on......there is more than one way to skin a cat...you can do this with another seperate switch so you can have the effect pre-juiced when you need it...or you can actually have it done (albeit not a true bypass) with one DPDT switch...it all depends on what you need the switches to do and what you have available to you...

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