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July 28, 2014, 12:26:57 PM
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DIYstompboxes.com  |  DIY Stompboxes  |  Building your own stompbox  |  rotary switch help 0 Members and 1 Guest are viewing this topic. « previous next »
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Author Topic: rotary switch help  (Read 494 times)
Valoosj
Posts: 882


Yorick


rotary switch help
« on: November 14, 2007, 10:36:12 AM »

I have never used these, so can somebody explain to me which one I would need for the following?

I'm building one stompbox with 4 overdrives in it, and I want to select 1 of those with a turn of knob. Should I get 4P3T or 3P4T?
And how the hell do I wire this? (just the switch, the rest is easy)
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Quote from: frequencycentral
You squeezed it into a 1590A - you insane fool!  icon_mrgreen
Quote from: Scruffie
Well this... this is just silly... this can't fit in a 1590B... can it? And you're not even using SMD you mad man!
Mark Hammer
Posts: 21879


WWW
Re: rotary switch help
« Reply #1 on: November 14, 2007, 11:22:49 AM »

In truth, a 2P5T switch is what you might need.  This would provide 4 alternate selections, plus bypass.  Of course, if you plan to have a stompswitch to select between bypass and whatever circuit has been selected, then a 2P4T is sufficient.

Many, if not most, people would likely use a chicken-head knob to turn the switch.  I mention this because if the knob itself has a pointing function, then you don't really need to use any sort of indicator LED to show which circuit is in play at the moment.  Having said that, though, if you want an ultra-sexy unit that changes colour with overdrive type, then you will want a 3P4T rotary.  One pole selects which LED and the other two poles move across the 4 different input and output connections.  In truth, it is no different than wiring up a DPDT or 3PDT stompswitch, except that the input/output leads have more places they can go to.

If you wanted a real über-pedal, you could opt for a 3P5T (or 2P5T), with the 5th selection being an external loop so you could patch in whatever else you wanted, including something not yet built/bought.

So, how do you wire it?  You will likely see tabs along the perimeter, and a smaller number of tabs on the inside.  Ritate the swuitch fully counter-clockwise.  Take your meter, set it to beeper/continuity-testing mode, and probe for continuity between one of the inside lugs and one of the outside lugs.  Now rotate the switch one click to the right and see if the continuity exists between that same inside lug and the outside lug just to the right.  If so, then you have a "map" of how the contact is provided.
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Valoosj
Posts: 882


Yorick


Re: rotary switch help
« Reply #2 on: November 14, 2007, 11:35:57 AM »

Thanks! I will go for the ultra sexy 3P4T


but 3P4T, that stand for 3 positions, 4 toggle right? the positions is how you can move the knobs 3 times over 4 sets of lugs right? Since you always have 1 overdrive selected it should only be able to move 3 times. Just making sure I get this right, because I almost opted for 4P3T (thinking that the T stood for the 3 turns you can make)
Logged

Quote from: frequencycentral
You squeezed it into a 1590A - you insane fool!  icon_mrgreen
Quote from: Scruffie
Well this... this is just silly... this can't fit in a 1590B... can it? And you're not even using SMD you mad man!
Mark Hammer
Posts: 21879


WWW
Re: rotary switch help
« Reply #3 on: November 14, 2007, 12:26:39 PM »

No. The P is for "poles".  The T is for "throw".  So, a 3P4T switch can "throw" three sets of contacts to any of 4 positions.

A 4P3T switch will only have 3 positions available.  A 4P4T will have the same number of "poles" but have 4 positions to select from rather than 3.

What you would need to select between 4 devices, switching both the ins and outs simultaneously, as well as an indicator LED, is a 3P4T (three poles, quadruple throw).
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Valoosj
Posts: 882


Yorick


Re: rotary switch help
« Reply #4 on: November 14, 2007, 01:17:56 PM »

ok thanks  Smiley
Logged

Quote from: frequencycentral
You squeezed it into a 1590A - you insane fool!  icon_mrgreen
Quote from: Scruffie
Well this... this is just silly... this can't fit in a 1590B... can it? And you're not even using SMD you mad man!
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