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Edge Lit Signs -- The Learning Circuit 09

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element14's The Ben Heck Show

Join Karen as she shares her enthusiasm for teaching STEM subjects, gives you what you need to know to get started on electronics projects, and more.

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The Learning Circuit
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In a previous segment, Karen showed you how to make a simple circuit using an LED.   Now, she’s going to apply that to a fun project by showing you how to make an edge lit sign.  To make an edge lit sign you add scratches to a piece of acrylic. Those scratches will interrupt a beam of light from an LED and show your design.

 

 

Karen is using acrylic that is 0.1 inches thick.  You could also use 1/8 inch or a similar thickness.  You don’t want to go to thin, because then it might break.  You don’t want to go too thick because it’ll be difficult to deal with.  When deciding the size of your acrylic, you want to stick around two to three inches in either rectangular or square.  If you go too big, the light of your LED won’t reach your design, and it won’t light up very well.  For this particular application, if you’re only using one LED, then you want a smaller design.

When drawing your design, you want to make sure that your lines are not going to be too thin because there will not be enough mass to catch the light significantly to really show off your design. When you make your design you want to make sure that you’re using nice, bold lines.  Karen draws extra lines within the border of the acrylic. This is because when it’s done, she’s going to be putting aluminum tape around the edges, and this is to make sure that the design isn’t covered up later.  When her design is done, she tapes the acrylic down so that it doesn’t shift, and so she can get good alignment between the acrylic and her design.

Next, you’re going to want to etch your design. You can use an exacto blade or any kind of hobby knife that has a sharp pointy end. She suggests using electric etchers if you have a child doing this.  For her example, she etched in a few different techniques so she could show you the differences of direction of scratch and how it affects your design when you place your LED.  She goes over some of her different etching techniques.  She suggests doing cross hatching, if you don’t have a specific design in mind. Scratch in opposing directions so that no matter where you place the light, it’ll still catch it. She recommends, though it’s not required, cutting a little notch in the edge of your acrylic to hold your LED in place and to keep the light pointing exactly where you want.

She cuts the acrylic and gives some advice on choosing your LEDs. A diffused LED doesn’t let as much light through, a colored LED is pretty good, but a clear one (red LED) is the best because it lets the most light through to get to your design.  When placing your LED against your acrylic, you want to make sure that the leads are on top of each other.  You’re going to be placing your battery in between them and you want to make sure that it’s going to be flat along with the acrylic.

Placing aluminum tape around the edges not only holds the LED and battery in place, but the white on the inside of the tape helps to reflect the light back in towards the design, making the sign brighter.

  • I love this project for essentially doing an art project with me nephew.  Here's my rookie question:  I can build a cool flasher circuit, but rather than having a switch that has to be turned off is there a way I can integrate a timer of some sort (IC555?) with a push button switch so that he can hit the button and it'll light up for a minute or two and then turn off?

  • in reply to burtamus

    Typically the adhesive side is what is touching the leads and battery and the adhesive is not conductive. Other tape can be used, it just means you need to have another type of tape on hand. I've done this project for workshops at libraries and schools and such. I mostly used the aluminum tape to hold the battery and LED together to keep the list of materials down to as few items as possible. Adding another type of tape would add another thing they'd have to buy.

    One benefit of aluminum tape over other tapes is that it molds fairly well and has a high tack. When I use some other tapes, they don't stick down tightly along the sides of the leads and sometimes the LED goes out because the tape isn't holding the lead down to the battery well enough.

  • Aluminum tape is conductive. How do you keep the LED's from shorting together. Why not just use Gaffer's tape? Very interesting idea. Thanks!!

  • in reply to wrustylane

    I plan on trying this method for making signs for my model railroad

    You may also want to experiment with epoxying plastic fibre onto the LED to provide small endpoint lighting.

     

    Plastic fibre optic is available as 'end light' and 'edge light' where the coating either keeps the light contained (end) or allows it to be lost out the sides, and comes in a range of sizes.

     

    Mark

  • A very good tutorial on how to edge light a piece of plexiglass with an LED.  I plan on trying this method for making signs for my model railroad (HO and Lionel 027 scale).  I would like to have seen how she mounted the LED in relationship with the battery.  I have several 3 V batteries I'd like to use and I noticed that she did not use a current limiting resistor when using the battery.  I guess she must have known the forward voltage rating of the LED as well as the voltage drop of the 3 V battery.  I believe an explanation of not having to use a current limiting resistor would have been more useful.  However, I do like this project since it gives me ideas on how to make my own personalized signs for my railroad using the edge lit plexiglass with LED's.  My railroad layout will be lit with LED's since they are really easier to use than standard incandescent bulbs and the fact that I can use my power supplies more efficiently with the lower powered LED's.  Thank you for posting this interesting video tutorial.  I learn more by watching others do something before I try the same thing.

     

    W Rusty Lane in eastern Tennessee (Witherington Place Railroad)

  • The video kinda skipped over mounting/fixing the batteries in, i think that would have been a nice step to drop in.

     

    Excellent project idea to do with the kids on a Sunday afternoon though!

  • Alternatively check this one out.

    Edge Lit signs

     

    Personally I'd polish the piece you cut to ensure the maximum light transfer from the LED.

    Interesting use of two colours . image

     

    Mark