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I'm looking for an 8 way DIP switch, that allows me to select between two different source voltage inputs. The most convenient would be a DIP switch with 10 pins: 2 inputs (e.g. +5 and +3.3) and 8 outputs. But of course an 8 way SPDT switch would do (24 pins), as I could just solder all the +5 and +3.3 input pins together.

At first I thought this would be the most common use of a DIP switch but I cannot seem to find such a switch.

Let me explain what I'm trying to do. I am making a breakout PC board for an Arduino Mega, which will have 8x RJ45 sockets (more accurately called 8P8C).

Each 8P8C socket will have 6 of the CAT6 cable cores reserved for breaking out IO pins, and the remaining two to power external devices.

I would like to be able to select the voltage supplied to external devices, individually for each connector. So I could choose that each CAT6 cable carries either 5V or 3.3V. But to reduce my board size I don't want 8 separate SPDT switches. Instead I'd like an 8-way DIP switch.

However upon looking, it seems DIP switches are almost exclusively SPST type. A quick google for "SPDT DIP" brings up a page on Mouser, however I cannot see any such switches.

This surprises me, as I would have thought the most common use for a DIP switch would be a "selector" switch of some kind.

Do these things exist, or have I misunderstood what I'm looking at?

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    \$\begingroup\$ How would you draw a pinout for an SPDT DIP switch? \$\endgroup\$
    – Hearth
    Commented Apr 23, 2020 at 2:56
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    \$\begingroup\$ why not use a jumper? \$\endgroup\$
    – jsotola
    Commented Apr 23, 2020 at 3:00
  • \$\begingroup\$ In one of the two ways already described above. Either 10 pins (2 inputs for the module, and 8 outputs) or 24 pins (2 inputs per output, for 8 switches, i.e. 3x8) \$\endgroup\$
    – hazymat
    Commented Apr 23, 2020 at 3:00
  • \$\begingroup\$ @jsotola Thank you so much for this answer. I'm very familiar with jumpers, but being new to PCB design it simply didn't occur to me and I was overthinking this one. Sometimes the answer is very simple. \$\endgroup\$
    – hazymat
    Commented Apr 23, 2020 at 3:02

3 Answers 3

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DIP switches don’t come in SPDT type. So, better to use 8 small SPDT switches, one for each RJ45. Small slide switches would do this nicely. Then you don’t have to worry about accidentally shorting +3.3V and +5V.

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You can do it with a 16-switch DIP. Every two switches become one output.

The downsides - You need to make 2 operations for each output (i.e. turn off 3.3, turn on 5.0). And you need to make sure you don't accidentally have both sources active (or they'll short!)

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8 pole SPDT switches are available in triple-in-line package.

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