Ballpoint Switch Is Oh-So Satisfying

Alright, here’s your quick and dirty hack for the day. The astute among you may recall [Peter Waldraff]’s bookshelf train build of a few days ago, and the fact that he used a switch made from a dead ballpoint pen to light up the scene. Fortunately, [Peter] wrote in to give us the details of this low-voltage sub-build, which you can see in the video after the break.

Essentially, [Peter] starts by making a shortened version of the pen. He modifies nearly every bit of it, including cutting down the ink cartridge, so if you try this, make sure the thing is all dried up first. Then, as he is screwing the point holder back on the barrel, he wraps elastic cord around the inside barrel in lieu of having sewing thread lying around. This cord along with some hot glue will hold a pair of paper clips to the sides of the point holder. When the pen is clicked into the writing position, it makes a connection between the paper clips and closes the circuit on whatever is wired into it.

What types of little hacks like this have gotten you through the build? Let us know in the comments, or better yet, write it up and drop us a tip. By the way, here is that bookshelf train build in case you missed it.

8 thoughts on “Ballpoint Switch Is Oh-So Satisfying

  1. I did something similar when I was about seven or eight, but I made use of the fact the cam inside rotates and created a push button that could have more than two states, it was fairly tricky to stop it jamming up, I used tiny bits of paperclip and aluminium foil and a lot of trial and error. I remember trying to add an electromagnet to turn it into a stepper relay but I got bored and moved on to something else. Who knows how many pens I broke in the process. I’m pretty sure I saved the ink tube from most of them and wrapped them in paper and tape so I could still write with them.

  2. By the time I was 7 years old I was cutting disposable aluminum pie plates into strips, then using them along with thumbtacks and blocks of wood to make momentary-contact switches, I used them to control flashlight bulbs, as well as electromagnets I made using wire wound on framing nails. Man, I wish I had one of those old Ray-O-Vac #6 ignition cells in my hand right now…

    About a dozen years later I was making a passive cross-fader circuit for the DJ business a friend and I started. I had an old 1 megohm stereo pot salvaged from some European stereo component, to be connected to the low-level magnetic cartridge outputs of the turntables. The shaft of the pot went all the way through the body and was secured with a nut.

    I didn’t yet know how a “proper” cross-fader worked, so I needed switches at the ends of the rotation to fully kill the signal of the “off” turntable. So I attached wire from a bent paper clip to the back end of the potentiometer shaft, and fastened an oblong ‘rubber magnet’ to it. I then soldered reed switches to the end terminals of the pots, and positioned them such that the magnet activated them at the ends of the rotation.

    Five decades later I’m a bit hazy on some of the details, but the contraption worked and served us until we got a proper DJ mixer.

  3. I built an analog 2-bit computer using 24 ballpoint pen switches just like these as AND and NOR gates. Helped solve quite a few non-linear differential equations with it.

  4. IIRC, the movie “Tobor The Great” had a fountain pen that controlled the robot, with a transmitter that the robot could home in on. You could summon the robot using the pen.

    Hmmm… I wonder how small of a GPS module and ESP module can be had today? You could send your GPS location via wifi to a net-connected optimus robot. Or maybe a cell modem.

    Probably couldn’t reproduce the pen using today’s technology. Wait a few more decades.

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