The frame is made with two small pieces of plexiglass. and the finished frame is no bigger than 5.5" but could be made to any size. LEDs inside light the bottom larger layer of plexiglass. The light will catch on anything that gets in its way between the LEDs and the edge of the plexi. I etched a message in the border which then becomes easily visible when the frame is lit.
The circuit I hacked together from some other more complicated designs is enterally analog and requires no voltage regulation. This means that the circuit should last a long time on a single 9v battery because the 555 timer chip is running directly off of the 9v battery and can continue to use the 9v as a power source as it falls well below the the 9v value. It should continue to work all the way down to ~4v as the 555 only needs 3.3v minimum and the led's only need ~1.4v . A micro switch underneeth turns off the pulsing effect when not in use and the frame is only turned on when picked lifted off of the surface it is resting on. This means it further saves power by only operating when someone is holding it and looking at it. Other modifications could easily be added to make it light sensitive or moation activated as well.
All of the electronic parts necessary should be available at your local electronics store as well and only basic soldering skills are needed to assemble it.
Step 1: What You Need...
The key to the circuit is using a 555 timer to create a slowly fading in and fading out pulsing effect wile not going completely dark. I have tried many different pulsing circuits until I found one I liked. I then modified it until it had the fewest parts possiable. You could make it without the pcb if you wanted and just solder the parts together. (pcb posted soon)
Step 2: Make the Frame
Step 3: Cut Out Frame
Step 4: Etch Frame
Lets first talk about how I made the template. I took my same photoshop file and wanted text to wrap around the curvy heart shape. This is very simple once you know how to do it. Use the pen tool and draw one side at a time from the middle top to middle bottom on separate layers. Dont worry if you have shaky hands or you mess up you can use the other pen tools to fix your curves and straiten everything out. Once you have your two curves drawn click on the Text tool and hover over one of the lines. You will see the icon change to having a line drawn through it. When you click you will now be able to type text on that path you just drew. Play with font sizes and styles to get everything the way you want it. Unless you are awesome with a dremel then I would suggest that you use as large and simple of a font as you can because many of the smaller details will not show up well.
Once you are happy with how the image looks flip it horizontally then print it out. I printed mine onto sticker paper but you can use regular paper and some scotch tape if you want. Sticker paper is very useful for projects like this so it is worth a few bucks to have some on hand. In the second image you can see the sticker paper stuck to the back side of the plexiglass with the picture taken with the camera flashing from behind to illuminate it. The reason for the flipping of the image is so that we can etch on the back side where imperfections will not show as much and the front side will look glossy and smooth.
The final image shows after the etching with the heart being edge lit by my flash for purposes of taking the picture.
Step 5: Finish Picture
Take your smaller heart and use it as a template to cut out the right shape using a sharp exacto blade. I cant stress enough how helpful it is to use new exacto blades for this kind of thing. Once it is cut out you can trim the edges or any imperfections by running the exacto blade along the edge of the plexiglass until both pieces are identical. You may also note that I drilled holes in the smaller heart. This is to join the two hearts together later with some small bolts and nuts. Make sure to cut holes in the plastic to match.
I thought the red plastic would be enough to keep a red ring of LEDs from leaking through the picture but it was not. I then concluded that tinfoil placed between the picture and red plastic would block all light for sure as well as not short out the LEDs. I used 3M #77 spray glue (another favorite product of mine) to glue the three pieces together. In the last picture you can see all three assembeled with the small bolts inserted. Use the exacto knife where needed to trim everything up. I used windex to remove all fingerprints etc from the plexi.
Step 6: LEDs
I took my borrowed grinder and ground my LEDs flat on two sides as you can see in this picture until they were the same thickness as the plexiglass. Simply hold an LED by the legs and apply light pressure against the grinding wheel and you will be done in no time. Remember to go slow. The LEDs are really just a diode thats covered in a hard plastic lens. You can grind it down or sand it to give LEDs a diffused look. In this case the sides are diffused but the tip still has the lens quality and throws quite an intense beam of pure red light. (the LEDs in this picture are the old ones.... the nice LEDs did not arrive from Hong Kong until the day before valentines day! I rebuilt it with them when they arrived)
I then used the hole I had cut in the larger heart and some tape to create a jig of sorts. I first soldered two LEDs at a time together by the negative (shorter) legs and bent the (longer) positive legs up at about 45deg. I taped 4 pairs of LEDs at equal 45 degree angles from each other and then soldered the now touching negative legs together. Then I bent down the positive leads so they were all touching. I took some cat5 networking wire to use for a lead. The negative (blue) is connected to all the negative LEDs. The positive wire is wrapped around all of the positive leads binding them together then soldered.
The end result can be seen in the video before the etching was added. The LEDS are flush with both sides of the plexiglass until somewhere near the middle where the curving upward of the positive legs begin to stick out. Thats ok though because we only need one side to be flush.
I took a small project box and trimmed the corners to fit the shape of the heart so that it would not show near the bottom. I used hot glue to attach it to the larger heart. Note I attached the BOTTOM of the box to the heart so that I could later have access to the screws that hold the lid on the back. After attaching I cut a hole gradually until the LED assembly that I soldered together fit in nice and flush. I then used a small blob of hot glue next to each led to hold it in place.
Step 7: Build the Circuit.
The 555 timer circuit is one of the best known IC's around. Apply voltage and it will produce a pulse which you can then use to do all kinds of things like build a clock etc. In this case I wanted to build a circuit that would slowly increase voltage to an LED then slowly decrease voltage again. The way to do this is to start with basic PWM. Pulse Width Modulation can be found all over online and here on instructables. Basically instead of changing the power sent to the LED I am sending it manny quick pulses of power every second. The more pulses I send per second the more power the LED receives. The fewer pulses I send the dimmer it becomes. We see this as bright and dim but in reality the LED is flashing on and off much quicker than our eyes can detect.
The 100k resistor and 100uF capacitor are the main components which control the rate of fading in and out. The capacitor serves as a reservoir so that when the power is cut to the led it slowly fades out instead of a quick flash on and off. The resistor controls how fast the circuit is powered up again and therefore controls how fast it fades on. I have built this exact circuit three different times with separate components and used variable resistors and different capacitors and many extra unnecessary parts. This circuit will produce the exact effect shown in the videos and should cost less than $5 for all the parts needed.
The Transistor (2N2222) is the smaller TO-92 package size. This acts as an amplifier/switch to control the LEDs. You cant connect the LEDs directly to the output of the 555 timer (pin 7) because the signal is too weak to power them. The transistor acts as both an amplifier and an electronic switch. It connects to the power source with the Collector leg, the output with the Base leg, and the LEDs with the Emitter leg. Whenever it receives a signal on the Base leg (from the output of the 555 timer) it applies power from the 9v power source directly to the LEDs through the 500ohm resistor. Wont this fry my LEDs though? It would if you connected them directly to the battery. Since we have built a PWM circuit they are all receiving 9v for a very short amount of time. So short in fact that measuring the voltage with a volt meter shows 1.3-1.6v which is perfect for almost all LEDs.
I connected all of my LEDs in parallel meaning that all of the positive leads are connected and all of the negative leads are connected. If one were to burn out the others would keep going. Also I only need one resistor for all of them and it makes soldering them together much easier.
I used a small piece of prototyping board that was ~1$ and cut it to fit in the box. You could solder everything together if you wanted or make a PCB but this worked well for me. I used double sided sticky foam tape to tape the circuit board inside the project box. The wires from the LED array (green/white) are soldered directly into the board. The negitive 9v battery connector is also connected directly to the board. The positive lead however is connected through a switch on its way to the board.
You can use any kind of switch you want to turn on and off the LEDs. You can use a simple toggle switch on the back side to switch it on and off, or a mercury tilt switch to turn it on when you stand up and off when you lay it down. I chose to use a small micro switch with a metal lever arm. In this way when the heart frame is picked up it will begin to pulse and when it is set down it will turn off. The switch has three connectors on it. Figure out which ones you would like to use and test it before gluing it into place. I used hot glue here as well. The metal leg sticks out just enough to trigger the switch when it is standing up. The weight of the 9v battery helps this as well.