Jim Keffer asked me to provide a tutorial for a backlit display frame that I made for an auction piece, so here it is. I've found that it’s best to use a push button that only turns the light on when it's pressed in, and goes off when the button is released. That way the battery lasts a long time. If you wanted to display your point backlit 24/7, you’d need an external plug and some controlling circuitry, but if you want to keep it simple

Materials

Display Frame/Case: I used 4.5” x 5.5” 'Riker Case' See above… Jim Keffer can quote you a price… Jim buys the frame pictured here by the case lot and gives PSK members a good deal. You can use a shadow box if you prefer, but the synthetic cottony stuff (polyester fiberfill) in Jim’s frame is perfect for holding a point in place. And it serves double duty as an effective diffuser for the specular light from the LED. Of course, if you want to display gargantuan sized points or many points at the same time, you’ll need a bigger box, and probably more LEDs. Jim has bigger ones too, 8x10, I think.

Light Emitting Diode (LED): : 5mm Round White, 3.3 volt, Radio Shack # 2760017 (2 pack) - $2.49 <<Don’t use an incandescent bulb for an application like this because of the heat.>> The LED suggested runs cool and is perfect for this use. I got mine at Radio Shack, but there are many sources both on-line and in local areas, depending on where you live. Any 3 volt LED will work. You don’t want super bright though, just a regular white LED.

Battery Holder: CR2032 Radio Shack Catalog # 2700009 - $1.49 If you want a reliable connection to the battery, it pays to get a holder. The holder pictured here is notorious for being hard to solder. I used one for my first lighted display project and found it difficult to solder, and I’ve been soldering for 50 years. If you have flux, use it, and if you don’t, get the lugs hot enough to melt the plastic at the case. If you don’t get it hot enough, you’ll have intermittent operation. These holders are designed for use on a circuit board, but I just bend the lugs over after attaching the leads and let the cotton hold it in place. That way it’s easier to change the battery when it dies. Vetco, an electronics supplier in Bellevue, WA has a good holder that solders easily, but they are $2.40 each.

CR2032 Button Cell Battery: The ubiquitous CR2032 is easy to find and not too expensive. A pack of four at Harbor Freight costs $3, less if you have a coupon or hit a sale. This is the preferred battery for “LED Throwies” that were in vogue for a while. If you buy a lot of them, you can get them for as low as $0.25 each at cheapbatteries.com. That’s a good thing if you intend on throwing them on a roof or someplace where you can’t get them back, which is where people throw them. Once they throw them, they’re pretty much gone, and they last about a week, longer if you get one that hasn’t been on a shelf for a couple years, and a lot less if a color LED is used, often less than a day with red or yellow LEDs. For our application, on for a few seconds at a time until your guests grow thoroughly fatigued from staring at your arrowhead collections, the battery could last for a couple years.

Push Button: Radio Shack $3.99. Normally Open, Momentary Closed, Single Pole, Single Throw, Radio Shack Cat. # 2750644. The picture that I borrowed from the Radio Shack web site has a red push button, but I prefer the black one. If you like red, the number is 2750646. This switch requires a ½” diameter mounting hole, and that requires a little bit of precision to fit into the ¾” deep frame used for this project. See the description below for details on how to do that. If preferred, one can find switches of much smaller diameter that would be easier to install, but not better, in my opinion. The suggested switch has the lowest profile of just about any push button I’ve seen.

Hook-up Wire: Radio Shack 22AWG, 3 rolls of 25’, #2781224 - $8.49. Whatever you have lying around will work. This circuit uses only a few milliamps at 3 volts.

Heat-Shrink Tubing: Radio Shack#: 2781610 $4.99.

Tools

Soldering Station: This tutorial presumes you know how to solder and that you have the soldering equipment needed. But, if you know how to do all that, you probably don’t need the tutorial. If you don’t have soldering equipment, Radio Shack has a number of inexpensive ($10 to $20) soldering pencils. They also carry a kit for $30 that will work fine for this project. There are numerous videos on YouTube regarding soldering, so you should be able to get all the knowledge you need at those sources.

Hot Glue Gun: Used to fasten the wires and components to the back of the frame. The LED needs to be secured so that it lights the correct area of the point and doesn’t shift around when people handle the display.

Spur bit: ½” for drilling the hole for the pushbutton switch. A spur bit is the best for this since the frame is made of heavy cardboard and the spurs will cut through cleanly.

Small “C” clamps: Used for accuracy in drilling the hole for the pushbutton switch.

Small pieces of scrap wood: Used for drilling a clean hole through the frame, in conjunction with the “C” clamps above.

The circuit diagram looks like this:

About as simple as a circuit can get: battery, load, and an on off switch. The CR2032 battery provides 3 volts to power the LED. The push button switch closes the circuit for as long as you push the button. Releasing the button breaks the circuit and the LED turns off. The LED will only light if it’s installed with the positive lead (the long one) attached to the positive side of the battery. Standard procedure is to place the switch in the positive line. There are very good reasons for that, mostly to prevent breaking the path to ground, which would be dangerous in your house wiring, but you could put the switch in this circuit on the negative side and it wouldn’t matter at all. Good practice is to keep the switch on the “hot” line.

A quick glance notes that there is no resistor in this circuit. Most circuits with a battery and single LED recommend a small value resistor on the order of 100 ohms or less. The purpose of the resistor is to limit the current through the LED to prevent premature failure, and/or too rapid discharge of the battery. Our plain white LED has a maximum forward voltage limit of 3.6 volts and it can safely dissipate 25 milliamps, according to its datasheet. Actual measurements with a digital ohmmeter showed 11.1 milliamps flowing through our circuit with a brand new battery, well below the rated current. We’ll only turn on the circuit for a few seconds at a time and only occasionally at that, probably.

The internal resistance of the lithium button cell is discussed a lot, but for the purposes of our project, this battery has enough internal resistance to keep the current low, and it is well suited for this application. The CR2032 should last a long time without noticeable dimming of the LED.

If anyone wants to use a different color LED, it is recommended that a series resistor of at least 200 ohms be added to the circuit to prevent current from reaching observed levels as high as 107 milliamps. A red LED with a 200 ohm resistor produced a current of 6.5 milliamps, which is acceptable. Colored LEDs are usually rated at only 1.7 volts and would be overdriven by our 3 volt battery without a current limiting resistor.

The component layout looks like this:

Circuit diagrams rarely look even remotely like the practical circuitry, but this one is pretty close. In this picture you can see the positive line in red, and the negative line in black, which are conventions. The longest lead on the LED will be soldered to the red line, and the shorter lead to the black. If you have already cut the leads on your LED, or scavenged one from a scrap circuit board, there is another way to determine the positive lead. There will be a flat surface on the plastic case on the positive side, or you can just touch the leads to the respective sides of the battery. It will only light when it is correctly oriented.

Drill the hole in the frame: The hole in the frame is a bit of a delicate procedure since the hole for this particular switch is ½” and the frame is only ¾”. It’s not too bad--if you find the center of the top wall of the frame, and push one of the pins that comes with it through your center point. The pins are installed in each side of the frame to hold pressure on the point to keep it in place.

Next, cut a pair of wood pieces to fit the wall of the frame where you intend to drill your hole. The wood is sacrificial and helps make a nice clean cut in the cardboard. Drill small holes in the centers of your pieces of wood so that you can align them with the centered pin hole that you made before.

Line everything up and clamp it down. . Then back the wood pieces with the corner of a short length of 2x4 or whatever you have handy, except fingers. Drill through the centers until you cut through the cardboard. If you have a nice sharp spur bit, it won’t take more than a few seconds. I used a hand held drill motor, and it worked perfectly.