How Does a 4pdt toggle switch work

[signalpaths]

Does anyone know of a good link on how a 4pdt togle switch works, as far as what is going inside?   I am in the process of making the ross/mxr dynacomp compressor off of tonepad.  The 4pdt toggle switch switches between the ross and the mxr and I'm not exactly sure how the posts on my switch relate to the schematic on tonepad.

Eric<signalpaths>

[Papa_lazerous]

a 4pdt switch works pretty much the same way a spdt does but there are 4 sets of contacts sitting parallel to each other, what is it you dont understand about it.  how to wire it or you actually want to know what goes on inside?

[Mark Hammer]

Although fear of litigation has made them a rarity these days, cast your mind back to the last time you went to a park and saw several see-saws, teeter-totters, or whatever you call them in your region attached to the same basic tubular-steel frame.  They were all in parallel and each one could go up or down independently.  Okay, now imagine that all the people on them agree to move up or down at the same time, and there are four see-saws.  That is precisely what you will see inside the switch if you were willing to sacrifice one and take it apart.

When the bat handle of the toggle is moved in one direction, the assorted rocker contacts inside (which are pivoted on a central fulcrum, like outr 4 see-saws connected to the same frame) all move down on the side opposite to where the handle is pointing.  "Down" means the person's feet are making contact with the ground and the connection is made.  The other end of the rocker contact, on the side where the handle is pointed, goes up in the air and loses its contact.

That's basically it.  The toggle handle merely serves as a kind of lever that bumps everything on one side up or down as the case may be.  The "ground" in our analogy is a set of contacts inside the toggle chassis which are the normally hidden part of the solder lug.  So, when the see-saw goes "down" on that side, the rocker contact touches both the metal fulcrum in the middle that it rests on, AND the inside part of the solder lugs on that side.

make sense?

[signalpaths]

Thanks Papa and Mark for the help

I'm just not sure how the switch I have corresponds to the Ross schematic.

The Switch I have has 12 pins total.  The pins are laid out in 2 rows of 6. 

The Schematic is here http://www.tonepad.com/getFileInfo.asp?id=24(hopefully i did that link right I'm new to the forum)

Also on the schematic I don't understand what NC stands for.  Maybe Not Connected?

Lastly in addition to the 4 dp switches there seems to be one more connection is this a ground?

And how does that correspond to the 2 rows of 6 on my switch?

thanks Eric 

[Papa_lazerous]

Ohhhhh I see what you want it for...............

Do yourself a big favour and dont waste your time.  the the comp decide if you prefer the Ross or dyna sound and stick with it 4pdt are expensive.  I dont rate the idea of that mod too much. I prefer the ross others will have different preferences I am sure.  there are so many mods for this build that will keep you busy maybe conentrat on them first??

[rogerinIowa]

I bought one of the 4PDT footswitches that Small Bear sells and at first I was stumped to see that it too had 2 rows of 6 contacts.... I was really used to thinking in terms of the 3PDT layout, you know, 3 rows of 3 contacts.

Solution? I got out the Digital Multimeter, a pencil, and a scrap piece of paper. I figured that know it is a 4PDT switch, so that means it has 4 poles that switch(or Throw) between 2 possible states...you know, press the switch it's in state #1. press again it's in state # 2. I made a little sketch of the switch layout (2 rows of 6 contacts).  So with  the DMM in Continuity mode I quickly figured out what contacts were connected in State #1 by probing each one and marking the connected ones down on the sheet of paper. labeling these as state #1. . Then I pressed the switch again and repeated the process , marking on my paper what contacts (poles) are connected to which in state #2.  I could see that a pattern had emerged and I could then tell which poles were connected in each of the switches 2 possible states.

If you do this what you will see is that there are poles that are connected in both states, just like in a 3PDT(which has 9 poles)...or a DPDT(which has 6 poles).

I don't know if I described that process clearly enough, but I hope it helps. Using this technique you can figure out any switch...even diagnose if a switch is malfunctioning.

And I think you SHOULD try that idea of switching between the Ross and Dyna comps. Even if the sonic differences are minute you will learn a lot.

Just thinking,

Roger

[signalpaths]

Thank you Roger, very helpful advice.

Eric

[smallbearelec]

Just a note: Decent quality 3PDT and 4PDT toggle switches have long been way too expensive. Truck will be at my door tomorrow with latest load from Taiwan that will include these among many other bits and pieces.

SD

[darron]

i've written a brief tutorial on true bypass switching here: link

it covers the DPDT (2pdt), and the 3pdt. The 4pdt will logically follow and you'll be shown it with pretty pictures in the article.

darron

[ethanw]

I haven't had a need for a 4PDT yet in my builds, what are the common uses? Switching between 2 entire effects in a box? My friend that has an online store asked me if he should stock them, I told him I wasn't sure because I could't figure out what kind of build requires them.

Ethan

[signalpaths]

Here's a link to what i'm using it for:
http://www.tonepad.com/getFileInfo.asp?id=24
When you get to the link click on the "click here" tab and the schematic will download

hope this helps

Eric

[MikeH]

I did the RODY mod you speak of, and it doesn't change the sound much to be honest.  Save that switch for something more useful.

[MikeH]

Although, I just noticed, all that switch does is connect those caps to ground.  So really, couldn't this be acheived by leaving the components on the board with the grounded end left hanging, and connecting all of the floating ends to ground using a single spst?

[darron]

stereo true bypass.... ?

[Mark Hammer]

Although, I just noticed, all that switch does is connect those caps to ground.  So really, couldn't this be acheived by leaving the components on the board with the grounded end left hanging, and connecting all of the floating ends to ground using a single spst?

You're unlikely to find a 4PST switch, and since we know that you CAN find a 4PDT stompswitch, that's what you use, except that you wire it up as if it were a 4PST.

Is it "worth it"?  Not my call, really, but since the changes to the Ross were intended to fix perceived shortcomings of the Dynacomp, rather than deliberately alter the tone or handling, I honestly can't see any value myself in being able to switch back and forth from one to the other.  If you wanted to learn about how the circuit changes affect "a compressor", fine, but how many of us are going to say "THIS song really calls out for the Ross, but THAT one desperately needs a Dynacomp to make it sound juuuuuuuuuuust right"?

Is it useful purchasing a 4PDT switch?  Yeah, I think so, just not for this particular purpose.  To my mind the absolutely best purpose you could put a such a switch to would be a simple passive means of reversing pedal order, perhaps in a loop selector, perhaps in a 2-in-1 effects pedal.  You could also use it to switch between two sets of settings, such as speed/depth on a chorus or phaser, or repeat and delay time on a delay line.