Lightsaber Lets You Pick Just About Any ‘blade’ Color

If you’re staging some epic Star Wars battles you could go original with Red or Blue lightsabers. But what if you decide you’re more of a fan of Jedi and want to go green? Or perhaps the prequels have inspired you to take on purple? Why choose at build time when you can adjust the color to match your mood.

[Phik] built himself a color-selectable lightsaber using RGB LEDs. He sourced a 5M strip of them from eBay for around $20. The pixels are not individually addressable, but each color channel can be driven with a pulse-width modulation signal to mix and match the final color. Now he could have gone with a microcontroller solution, but [Phik] decided to give himself a bit more of a challenge. He built three PWM circuits based on a 555 timer which can be adjusted with a potentiometer. It’s not going to kill any insects, but the keep-it-simple-stupid aspect of the project makes it something we could actually build ourselves. The same cannot be said for most of the replica builds we see.

15 thoughts on “Lightsaber Lets You Pick Just About Any ‘blade’ Color

      1. Much better, thanks! Looks to be a good guide.

        I’m curious, do you have any problems with the 555’s interfering with each other? I did something similar a while back and noticed two 555’s tended to lock on to the same duty cycle when they were set similarly. It’s due to the large (>200ma) shoot-through current when the 555’s switch. Took a surprising amount of power supply filtering, isolation, and careful routing to eliminate. Just wondering if others have had the same problem.

    1. I haven’t noticed anything like that happening. Might be because I’m not sinking that much current through the 555’s due to the MOSFETs. Did you have a decoupling capacitor between power and ground? 555’s don’t like not having those in my experience.

      1. The problem persisted even if I disconnected the outputs completely.

        I was using the typical 0.1uF decoupling caps between VCC and GND, as well as caps to GND on the control pin. Operating frequencies and timing resistors/caps were all in conservative and datasheet recommended ranges.

        From there I tried the following, in this order:

        1) Increased the main power supply cap.
        2) Replaced 556’s with 555’s, with individual decoupling caps.
        3) Added a 10uF electrolytic in parallel with each 0.1uF.
        4) Switched to strict star routing for VCC and GND.
        5) Added a 10-ohm resistor in series between VCC and each set of decoupling caps.

        Each provided an incremental improvement, but none completely solved the problem. I ended up switching to SG2524’s, which worked perfectly with no special measures. It was so frustrating that I never used 555’s again.

        Though I still wonder why I was having such difficulties, I’m glad you’re not!

  1. LED strips are kinda ill-suited for this without a better diffuser. :(

    I don’t know how bright a red, green, and blue Luxeon would be on one of those 3-LED stars, but I’d go with that before I did a build like this.

  2. Wait… he fakes an analog signal with PWM through a 555 timer… which he then controls with a potentiometer which generates the analog signal he’s faking? Am I missing something? Why not just drive each channel with a potentiometer inline to voltage in the first place, why the PWM at all? >.<

Leave a Reply

Please be kind and respectful to help make the comments section excellent. (Comment Policy)

This site uses Akismet to reduce spam. Learn how your comment data is processed.