A Blindingly Bright Larson Scanner


This hulking monument to illumination is [DJJules’s] 6-foot-long Ultimate Larson Scanner. If you’re scratching your head in confusion, the Larson Scanner is the ever-popular scrolling LEDs seen on KITT (the car) from Knight Rider and on Cylons in Battlestar Galactica (1978), named after the creator of the series.

[DJJules’s] iteration consists of sixteen 10W LEDs, each mounted on a heat sink which bolt on to a 6′ long piece of angle aluminum sourced from a local hardware store. He used a basic MOSFET constant current driver for each LED, attaching the MOSFETS to the heat sink with 4-40 screws. Each LED module then connects to a TLC5940 LED driver breakout board from Sparkfun, which plugs into an Arduino Pro Mini.

Check out the Instructables page for the source code and other important details, including safely powering the build (the LEDs can draw around 1A each), then grab your sunglasses and stick around for a quick video below.

31 thoughts on “A Blindingly Bright Larson Scanner

      1. Yeah – I’m pretty sure on their lesser-powered modules, around the 1-3W range, they warn you not to view them directly because the intensity is so high. This is much, much brighter.

        Using these in a performance without a diffuser is beyond irresponsible.

        1. Since the LEDs aren’t focused the intensity of the light is inversely proportional of the square of the distance. So from a distance of three meters the light is only 1/10th of what you get at one meter. And at 10 meters the intensity is only 1/100th of the one meter level.

          So if by performance you mean that people can go up and put their faces next to the leds I might agree with you a bit. But on a music scene when a band is playing your “beyond irresponsible” is just a ridiculous statement from someone that seems overprotective.

          1. The inverse-square law applies to all light. They’re still too bright! I dunno where he plays but 10 metres is a bit further away than you’d expect a crowd, even 3 metres is.

            It’s a lovely effect and everything, I just wouldn’t put it near people.

        2. It’s also kind of cheesy, I didn’t think DJs used stuff like that since the 80s. And yeah it’s too bright to use with people anywhere near it. It doesn’t need to blind them, but even dazzling people, especially in a dark room, is a bad idea.

          Mounted on a satellite, I think, would be pretty good.

          1. Greenaum, if the light is focused/collimated the inverse square law doesn’t apply.

            But all this sissy whining about blinding and irresponsible stuff is really ridiculous. Maybe you don’t realize that a 10 watt led is not a frikking laser beam. These leds are not brighter than a regular 60-80 watt incandescent light bulb (with a back reflector) – and if the light bulb is using clear glass the area of emission is also probably about the same on the led and the bulb.

            I suppose you also think that the ubiquitous xenon strobe light in the discos in the old days are irresponsible, dangerous and a bad idea as well. Not to speak about photo flashes – a regular photoflash unit for a DSLR have enough power do burn the hair on your arms in milliseconds if you get too close.

          1. If you read my post you see I wrote “PWM” not “drive”.

            The Ultimate Larson Scanner uses drivers after the TLC5490 to drive the LEDs. So the TLC5490 is used to generate the PWM signals. Hence the Arduino would be quite fine to deliver the PWM directly to the output drivers in exactly the same way the TLC5490 is used.

  1. Very cool to see the TLC5490 paired with external switching fets! I have always wondered how easy it would be to get it working like that. Time to revisit my high current LED projects…

        1. I’ve got a friend that wants a beefy flashing light on his Harley, I’m thinking of setting him up with a 100 watt module and a booster for taking the 12 volts up to 35 to drive it. If the flashing is at a low duty cycle like 5-10% the cooling requirements is hopefully a bit less – maybe just a piece of copper plate would be enough for some shorter bursts of “get-the-h*ll-out-of-my-way” flashing.

  2. If you really felt like doing some surgery, it looks like the diode arrays are set up in a series/parallel scheme that would allow a Larson scanner to be built within the diode itself (or you could just hit yourself on the head with a rock since it’d be less painful). But oh the joy if it worked.

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