DIY Guitar Pickup Winder Counter

David Shepherd
David Shepherd Mojo Guitar Parts Manager Custom Wound Pickups

David Shepherd of Custom Wound Pickups shows how to make an inexpensive pickup winder counter using a $1 calculator and a $5 magnetic reed switch. This particular counter method is perfect for someone who is learning how to wind pickups as well as the occasional rewind in a busy repair shop. I recommend this counter to be used with a variable speed hand drill for the most economic and easiest way to wind pickups. It is however very limited on how fast you can wind before the calculator stops counting. My guess would be around 400-500 rpm’s max before it can’t keep up, but you will clearly see it stop counting after a certain speed and learn the limit. Speed should not be important anyway if you are learning. That said, I give this calculator counter idea a big thumbs up for getting started. The calculator counter idea has been around for quite some time so I do not take credit for this. I chose to describe this method because it is very inexpensive to make and easy to use. I also had to look at how available the parts would be locally. There are tons of other counter ideas that work great too and are inexpensive, but finding the parts locally can be challenging or impossible for some. The parts for this counter are conveniently available at most electronics stores or hardware stores and calculators are just about everywhere. I hope you will find this information helpful and good luck with your success!

Tools you will need

  • Basic calculator
  • Magnetic reed switch with wire leads
  • Soldering iron and solder
  • Razor blade
  • Small drill bit or file
  • Hand drill
  • Screwdrivers

(click thumbnail images to make larger)

  1. Remove the back from the calculator.

  2. Remove the battery if possible.
  3. Using the razor blade, carefully scrape the two (2) holes on the PCB pathways over the “=” button of the calculator until bare copper is exposed.
  4. Drill a small hole into the side of the calculator for the reed switch wires to feed through. All calculators are different so use your best judgment on where to drill a hole. On small thin calculators you may find using a small needle file to set a groove for the wires to feed into the calculator is best.
  5. Feed the 2 wires from the magnetic reed into the calculator through the hole. You may want to use silicone caulk or glue to hold the wires secure in the hole or you can get fancy and use a rubber grommet.
  6. Solder the 2 leads from the reed switch to the PCB holes over the “=” sign. It doesn’t matter which wire goes to which hole. Do not bend the wire or move the solder joint once your connection is made or you will risk breaking the pathway on the board.
  7. Re-install the battery
  8. Put the back on the calculator
  9. Turn the calculator ON and press + 1.
  10. Now move the magnetic assembly across the reed switch (approximately 1/8” to 1/4” space between the magnet assembly and reed switch) and watch it count up after each pass of the magnet. You will need to orient the magnet correctly for the switch to work which is immediately apparent. It will either work or it wont, depending on the direction of the magnet. Just flip it if it doesn’t work.
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  • Kenboudreau

    Very cool idea, I’ll be giving it a go soon!!
    Thanks for posting.

  • Apu Nahasapeemapetilon


  • Nicholas Burman

    Works like a charm – thanks for this! It took me two calculators to get it right (I burnt out the contacts with my soldering iron on the first one!). 

  • Jeepcjs

    It’s hard finding a calculator with a printed circuit board anymore!!!

  • Gryphon Guitars

    I’d tried to find the reed switch at the local ‘Shack – no luck BUT I did get a roller switch that serves the same purpose and with an arm extended it ticks the switch on each revolution. Same difference, right? Great article!

    • Ian Pender

      I know this is an old comment, but did you ever make a counter with that roller switch you mentioned? I found a reed switch locally, but I’m finding the 400 rpm speed limit to be a bit limiting. I was considering replacing it with a photo interrupter, or an optical switch of some sort, but what you described sounds far simpler.

  • Trevor Taylor

    A Cheap pedometer $1 on Ebay is easier to get working than the carbon contacts in most modern calculators. .Cheers

    • Michael Moriarty

      Why not attach the pedometer to the bobbin you are trying to wind? Every time it rotates the pedometer will count.