Edge-lit Pendants Show Two Layers are Better Than One

Engraved acrylic lights up nicely with LED lighting. Simply engrave clear acrylic with a laser engraver, then edge-light the acrylic and watch the engraving light up. This badge made by [Solarbotics] shows how they used this principle when creating some pendants for an event that performed particularly well in the dark.

The pendants they created have two engraved acrylic panels each, and that’s about it. Two LEDs and a CR2032 battery nestle into pre-cut holes, and the engraved sides are placed face-to-face, so the outer surfaces of the pendant are smooth. By using some color-cycling RGB LEDs on one panel and blue LEDs on the other panel, the effect is that of an edge-lit outer design with a central element that slowly changes color separately from the rest of the pendant.

The design stacks the LED leads and coin cells in such a way that a simple wrap of tape not only secures things physically, but also takes care of making a good electrical connection. No soldering or connectors of any kind required. [Solarbotics] found that CR2032 cells would last anywhere between a couple of days to a week, depending on the supplier.

This design is great for using a minimum of materials, but if that’s not a priority it’s possible to go much further with the concept. Multiple layers of edge-lit acrylic were used to make numeric 0-9 display modules as well as a full-color image.


Before There were Nixie Tubes, There Were Edge-Lit Displays?

We’ve seen a bunch of replacements for nixie tubes using LEDs and edge-lit acrylic for the numbers. But one of the earliest digital voltmeters used edge-lit Lucite plates for the numbers and a lot of incandescent lamps to light them up.

[stevenjohnson] has a Non-Linear Systems Model 481 digital voltmeter and he’s done a teardown of it so we can get a glimpse of the insides. Again, anyone who’s seen the modern versions of edge-lit numeric displays knows what they are: A series of clear plastic plates with numbers (or characters) etched into them, each with a light source beneath them. You turn one light on to light one plate, another to light another, and so on. The interesting bit here is the use of incandescent bulbs and the use of sequential relays to cycle through the lights. The relays make a lot of racket, especially with the case open.

[stevenjohnson] also notes that he might have made a mistake opening up the part of the machine where the plates are stored as it took him a bit to get the plates back in place and back in the unit. We’d imagine it was pretty loud if you were taking a lot of measurements with this machine, although it looks great inside and, obviously, the idea is a pretty good one. Check out this edge-lit nixie tube display or these edge-lit numeric modules.

[via boingboing]

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Full-Color Edge-Lit Laser Cut Acrylic

Edge-lit art has been around for a very long time, and most people have probably come across it in a gift shop somewhere. All it takes is a pane of transparent material (usually an acrylic sheet) with the artwork etched into the surface. Shine a light into the sheet from the edge, and refraction takes over to light up the artwork. However, this technique is almost always limited to a single pane, and therefore a single color. [haqnmaq] wanted to take this idea and make it full-color, and has written up a great Instructables tutorial on how to accomplish this.

If you want to make something like this yourself, the only thing you really need is a laser cutter and some basic electronics equipment. The process itself is so straightforward that it’s surprising that it isn’t more common. You start by taking a photo of your choice and use an image editor to break it up into three photos, one for red, one for green, and one for blue. Each of those photos is then etched into an acrylic pane with a laser cutter. When the panes are positioned in front of each other and edge-lit with their respective LEDs, a full-color image comes to life.

This isn’t the first edge-lit artwork project we’ve featured, but it definitely has the highest fidelity. Because [haqnmaq’s] technique uses three colors, you can use his tutorial to reproduce any photo you like. You could even take this a step further and create animated photos by adding more panes and lighting them up in the correct sequence!

A Transparent 7-Segment Display

Though [Connor] labels it as a work in progress, we’re pretty impressed with how polished his transparent 7-segment display looks. It’s also deceptively simple.

The build uses a stack of seven different acrylic panes, one in front of the other, each with a different segment engraved onto its face. The assembly of panes sits on a small mount which is placed over seven rows of LEDs, with 5 LEDs per row. [Connor] left an air gap between each of the seven individual acrylic panes to clearly distinguish which was lit and to match the separation of the LED rows. To display a number, he simply illuminates the appropriate LED rows, which scatter light across the engraved part without spilling over into another pane.

You can find a brief overview and some schematics on [Connor’s] website, and stick around for the video demonstration below. We’ve featured [Connor’s] work before; if you missed his LCD data transfer hack you should check it out!

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LED retrofit for vintage edge-lit numeric display modules


This single digit display is an old edge-lit module that [Ty_Eeberfest] has been working with. The modules were built for General Radio Company and have a really huge PCB to control just one digit. [Ty’s] modules didn’t come with that driver board, so he was left with the task of controlling an incandescent bulb for each digit. After a bit of thought he figured it would be much easier to just replace the edge-light bulbs with a set of LEDs.

We’ve seen these exact modules before, referenced in a project that created an edge-lit Nixie tube from scratch. Each digit in the display is made from a piece of acrylic with tiny drill holes which trace out the numerals. The acrylic is bent so that the edge exits out the back of the module where it picks up light from the bulb. [Ty] laid out his circuit board so that each LED was in the same position as the bulb it was replacing. As you can see, his retrofit works like a charm.

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Edge-lit musical birthday card

[Monirul Pathan] decided to make the card as unique as this gift when getting ready for a birthday. He designed and built his own musical card with LED edge-lit acrylic to display the message.

The electronic design seeks to keep things as flat as possible. The card-shaped acrylic panel has a void to fit the PCB exactly, and the components are relatively flat. One thing we found quite interesting is that the ATtiny85 which drives the device is surface mounted, but it is not a surface mount component. The layout includes though-hole pads, but instead of drilling holes [Monirul] clipped off the excess of the DIP legs and soldered the remainder directly to the copper. We suppose this isn’t going to get a lot of use so it just needs to hold together for one day.

As you can see in the video after the break, the speaker plays ‘Happy Birthday’ followed by ‘Under the Sea’. At the same time, four blue LEDs pulse to the music, lighting up the words that are engraved in the plastic.

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Edge-lit Nixie tube is sheer brilliance

It’s not often that we see something so brilliantly simple we’re left reaching for our checkbooks while wondering exactly how we never though of that before. [Jürgen]’s edge-lit Nixie display is one of those builds.

[Jürgen]’s modern take on a Nixie display uses ten laser-engraved pieces of acrylic to emulate a Nixie numerical display. In the base of the display are 10 LEDs, each shining onto the side of a piece of acrylic. When an LED lights up, you can clearly see the corresponding number. Edge-lit displays are old hat, but talking about the possibility of an RGB Nixie-style display is really neat.

The build was inspired by an antique edge-lit display that performed the same function as the ever-popular Nixie tube with 10 miniature light bulbs and light pipes. The ancient edge-lit displays came in a rectangular enclosure that worked very well for panel-mount uses, but [Jürgen] stuck to a more traditional cylindrical orientation. All we want to know is when a manufacturer in China is going to start building these. Check out the demo of the edge-lit Nixie after the break.

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