Switch Question

I haven't done any electronics in years so please excuse the simple question. Google made me confused.

A device has two three-wire ribbon cables. I want to put an On-Off-On two-position switch on the cables that functions like this: 1) The same circuit as the uncut cables

AAA --- AAA BBB --- BBB

2) The cables are "swapped"

AAA --- BBB BBB --- AAA

Is this a 2P3T switch?

The application is switching a Logitech trackball between right-hand and left-hand buttons by a switch on the trackball. I write software for a living and want to have a right-hand trackball on the right side of my keyboard and a left-hand trackball on the left. I've given up trying to do it in software so "physicaly swapping" the buttons is the easiest solution I know of. I could easily cut-and-solder but would prefer a switch for flexibility.

The manufacturer's page:

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The cover off showing the two (solid wire) three-wire ribbon cables:

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Thanks.

-- Mark

Reply to
Mark Jerde
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A switch pole is a circuit. A throw is a switch position. So if you want to swap between 2 pairs of 3 circuits you need a 3 pole double throw switch. But you don't want ot swap between two pairs of 3 circuits for one 3 circuit output, you want to reverse connect 3 circuits. This can certainly be done with a 6 pole double throw switch. The A1 output (the contact that swings between two other connections) will swing between the A1 and B1 input. The A2 output swings between A2 and B2 inputs, etc., all the way to the B3 output that swings between the B3 and A3 inputs.

However, in your case, I am willing to bet that one of the A conductors is directly connected to one of the B conductors. If you check with an ohm meter, I think you will find a common wire in both of the 3 conductor cables. For instance, if, say A1 is always connected to B1, then they are interchangeable and need not be switched. So you may need only a 4 pole double throw switch to reverse the remaining 2 pairs of circuits.

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Regards,

John Popelish
Reply to
John Popelish

First off, you probably only need to swap two of those three lines, I bet one of them on each side is Vdd or Gnd.

Second, the switch you want is a DPDT or 3PDT "on-off-on" switch. The middle "off" doesn't count as a "throw".

Third, why do you need the center "off" position?

Fourth... buy two, swap the cables in one, and plug them both in. They're USB, you can do that.

Reply to
DJ Delorie

Thanks for the clear explaination.

Good point, by inspection it appears the middle wire in each cable is ground. I hope the batteries in my mm haven't leaked... ;-)

-- Mark

Reply to
Mark Jerde

John's right, 4PDT or 6PDT, double what I said.

Reply to
DJ Delorie

Good point.

Per John's reply reverse-connecting 2 or 3 circuits require 4PDT or 6PDT, right?

It's not needed. The term "On-Off-On" came from a googled page, describing "break before make" two position switches. I can't see it would make any difference in this application.

Swapping cables on a few is no problem, I have at least a dozen. (My previous-favorite mouse was discountinued so I bought a lifetime supply of this model.) The switch is mostly for tinkering, and maybe getting back into electronics again. My oscilloscope has been in its box since 1989. My daughter is now grown and moved out, so I'm thinking of putting up a bench in her old room. ;-)

-- Mark

Reply to
Mark Jerde

(snip)

(snip)

When buying switches, they are described as either on-off-on or on-on. The first has 3 distinct positions, the middle one being a stable switch position that disconnects the poles from both choices. The On-on types come in make-before-break and break-before-make, but do not have a stable middle position.

Here is an example of a 4 pole double throw miniature toggle switch that might work for you.

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?Name=360-1873-ND

Sorry about the price.

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Regards,

John Popelish
Reply to
John Popelish

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It might make a difference if there was a center OFF position, since
both cables (except for the common ground) would be left floating with
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Reply to
John Fields

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