Sparkfun Illuminated Switch Schematic

I got these really nice illuminated switches from Sparkfun to control the Rubens’ Tube I built with a friend. Wiring them up was strangely non-obvious so I figured I’d post a schematic here.


  1. Michael says:

    Wasn’t half of the problem that the switches are poorly labeled when we got them? Do you remember how they were labeled? That might help as well for reusing them in the future.

  2. lee says:

    Michael, my diagram is a pretty good representation of the actual switch. So a person should be able to hold up the switch, compare it to my image and go from there.

  3. Michael says:

    I just looked this up yesterday. It’s a real pain to reverse engineer wiring of things that are voltage sensitive without this schematic. The built in switch led drops the voltage enough to really effect things. It’s a little frustrating based on how nice these switches are to use.

  4. lee says:

    Heh, years later and they haven’t posted a schematic. I posted a “review” with the schematic on the Sparkfun site. Time flies, eh?

  5. Michael says:

    Too be fair, A LOT happened in the interim. My brain always wants to run positive on the device line for some reason.

  6. Tom says:

    I just bought one of these for a project. Your schematic is very helpful, thanks. Do you know if this switch has an internal resistor? The similar switch on the Adafruit site indicates there is an internal resistor in their switch. Any reason to think they’re not all the same? Sparkfun is still silent on any useful information about this switch. I’ll be using with batteries for a 3V power supply.

  7. Lee says:

    It’s been a while since I worked on this but, no I don’t think there’s an internal resistor. If you want to power the internal LED, you need an external resistor like I show in the schematic. Though, if you’re running just 3 volts through it, maybe you don’t need a resistor at all to make the LED light up. I see a note on the Sparkfun site that says “Note: The LED can be illuminated with as low as 3.3V.” Go for it!

    Get out your trusty multimeter and find out if there’s a resistor in it! And please post back here for the next intrepid electronics explorer to discover!

  8. Michael says:

    So, this is terrible of me, but I’ve run these switches on 12vdc all day long without ever looking for a resistor. They’ve lasted for hundreds of hours without a problem, which makes me think they’ve gotta have something. In my experience, vanilla LEDs have a tendency to aggressively release the magic smoke when exposed to voltages like that sans resistor.

Leave a Comment

Do not write "http://" or "https://" in your comment, it will be blocked. It may take a few days for me to manually approve your first comment.