Human-Powered Laser Gun Makes Battery-Free Target Practice

[Dirk] shared a fascinating project of his that consists of several different parts coming together in a satisfying whole. It’s all about wanting to do target practice, indoors, using a simple red laser dot instead of any sort of projectile. While it’s possible to practice by flashing a red laser pointer and watching where it lands on a paper target, it’s much more rewarding (and objective) to record the hits in some way. This is what led [Dirk] to create human-powered, battery-free laser guns with software to track and display hits. In the image above, red laser hits on the target are detected and displayed on the screen by the shooter.

Right under the thumb is the pivot point for the lever, and that’s also where a geared stepper motor (used as a generator) is housed. Operating the action cranks the motor.

There are several parts to this project and, sadly, the details are a bit incomplete and somewhat scattered around, so we’ll go through the elements one at a time. The first is the guns themselves, and the star of the show is his 3D printed cowboy rifle design. The rifle paints the target with a momentary red laser dot when the trigger is pressed, but that’s not all. [Dirk] appears to have embedded a stepper motor into the lever action, so that working the lever cranks the motor as a generator and stores the small amount of power in a capacitor. Upon pulling the trigger, the capacitor is dumped into the laser (and into a piezo buzzer for a bit of an audio cue, apparently) with just enough juice to create a momentary flash. We wish [Dirk] had provided more details about this part of his build. There are a few more images here, but if you’d like to replicate [Dirk]’s work it looks like you’ll be on your own to some extent.

As for the target end of things, blipping a red dot onto a paper target and using one’s own eyeballs can do the job in a bare minimum sort of way, but [Dirk] went one further. He used Python and OpenCV with a camera to watch for the red dot, capture it, then push an image of the target (with a mark where the impact was detected) to a Chromecast-enabled screen near the shooter. This offers much better feedback and allows for easier scoring. The GitHub repository for the shot detector and target caster is here, and while it could be used on its own to detect any old laser pointer, it really sings when combined with the 3D printed cowboy rifle that doesn’t need batteries.

Not using projectiles in target practice does have some benefits: it’s silent, it’s easy to do safely, there is no need for a backstop, there are no consumables or cleaning, and there is no need to change or patch targets once they get too many holes. Watch it all in action in the video embedded below.

This has some things in common with HomeLESS, an open source laser shooting simulator. We first covered HomeLESS several years ago and the project is still alive, so if this kind of target shooting interests you, be sure to check it out.

15 thoughts on “Human-Powered Laser Gun Makes Battery-Free Target Practice

  1. The laser pistol was one game in what was probably the cheapest 90’s game show in Finland. It was similar to the military training system (TASI/KASI) that had an IR laser pointer mounted to a gun. It detects the impact of the striker to count a shot, so there’s no modification to the weapon itself.

    Young Jasper Pääkkönen performing:

    Other events in the show: “Red or black card?”, “Rubber band football”, “Guess how long is two seconds.” etc.

  2. Hey! Dirk here, thanks for posting this!

    I had actually mostly finished things about 6 months ago, but ran out of steam, so decided to finish it up ASAP recently, while I had energy from being able to recharge, working from home.

    That’s reason 1 for being light on details and all over the place.
    Reason 2, is that I don’t really know what I’m doing, and assume everyone else knows better than I do!
    I’ve already had friends cringing at my “circuit”.

    But I’ll gladly make a follow-up video showing how to crank ‘n store ‘n discharge the energy from the stepper.

    Thanks again for the write-up, and stay safe everyone.

    1. Yeaaah, I hadn’t thought that through very well.
      This was actually a “reshoot” of sorts, because I forgot to wear pants on the good take.

      So I was focusing so hard on wearing pants that I neglected to connect the shirt with the subject matter.

  3. Ha ha, that’s pretty funny!

    Awesome project. And it’s even more impressive with all the new skills you learned along the way. The mechanical design and integration problems you solved would be difficult even for experienced makers.

  4. It would be interesting if the target to aim moves too. Could even be another laser dot or projection, and the movement for the projection device and camera could be done by using an x-y servo mechanism!

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