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Here's an example of a common ABY box:

enter image description here

Why do these pedals use AND and OR? Is there a technical reason/limitation that causes this to be used over something like a toggle switch for A and a toggle switch for B? Or is AND+OR better from a usability standpoint?

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  • It probably makes the electronics easier. It sure doesn't make it easier to use, IMHO. Mar 6 '16 at 20:05
  • As these are designed to be foot operated toggle switches would be useless. Mar 6 '16 at 20:52
  • @davidstrachan I'm sure the asker means toggle in the sense that they are on-off switches that would be foot-operated type, not toggle in the sense that they would have a paddle-type switching handle. One thing that just occurred to me is if it were two on/off type switches then there would be a switch position of both off, and that would be a downside in terms of wiring and functionality. Mar 6 '16 at 21:02
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    @ToddWilcox Correct about the switches. I thought about the off/off situation but that seems like it could be useful - and certainly wouldn't add much in the way of complexity... Mar 6 '16 at 21:09
  • The "edge case" problem with the ABY (in my mind) is that they are latching switches, so if I want B > A+B > B, {works as designed} but if I want B > A+B > A {I tap dance}. I expect that some sort of mechanism to disengage the A+B latch on any A/B button press and the addition of a visual indicator of A/B state regardless of A+B state would solve this. Does this exist?
    – Yorik
    Mar 10 '16 at 21:48
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AB boxes use a footswitch (OR) to toggle between two outputs and a second footswitch (AND)to combine the ouputs . The image below uses double-pole, double-throw (DPDT) switches, although singlepole, double-throw (SPDT) is all that is required. The DPDT swiches are probably used as these are the most versatile and simplifies stock.

If you look at the OR switch you will see that if 1&2 are connected B is connected to C(follow the coloured wires). If 3&2 are connected A is connected to C.

Looking at the AND switch you will see that if 1&2 are connected both A&B will be connected to Center image description here

Here is a link for information on switches

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  • This is what I expected to hear...I was hoping the answer would be something more interesting than, essentially, dpdt is cheaper/simpler than 3pdt, though. Mar 6 '16 at 22:23

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