As you all may or may not know, I love LEDs! Now, since the title of the contest is "Show Your Heart Valentine's Day Project", what could be more appropriate than a Beating LED Heart on a T-shirt?

Here's how YOU can show YOUR Heart on Valentine's Day!.... or force your valentine to show his/hers. ;-)

100_0517.MOV
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Step 1: Get the Materials

You Need:
A T-shirt that you are willing to sacrifice in the name of love
99 3mm red LEDs (1.8-2.1V @ appx 10 mA)
two DM7474 IC's (flip flops)
one DM7402 IC (2 input Nor gate)
one ne555 timer
one 224 pf capacitor
one .47 uf capacitor
two 4.7 uf capacitors (over 9 volts)
.01 uf capacitor
one variable resistor (100k ohm max or a 47k resistor)
one 470 ohm resistor
two 1k ohm resistors
one 560 ohm resistor
1 nine volt battery + clip
Foam
Tape
Hard Drive cable (or wire)
Telephone cable (not needed but helpful)
Another T-shirt or some fabric
Needle + Thread (or a sewing machine)
wire cutters
Soldering Iron
Solder

pm me for the original heart template, I don't know how to attach original jpegs

Step 2: Make the Heart!

Tape the template I provided onto the T-shirt over where your heart would be.
Take the 6X6 piece of foam and put it under the template
Now take 42 LEDs and punch the leads through the holes, through the t-shirt, and into the foam

Make sure that the cathodes are all facing towards the center of the Heart, and the anodes are facing away from the Heart.
Tape over the LEDs with duct tape, to get extra fancy points use red, the color of love (the color doesn't matter, you're going to rip it off later)

Bend the leads so that the LEDs stay in place.
Strip a few of the hard drive cable wires entirely (see pic)
Starting with the "depressed" LED, solder the anodes of the first group of 14 LEDs together
On the 14th led, solder the cathode to the anode of the 15th led and then continue soldering the next group of 14 anodes together.
On the 28th led solder the cathode to the anode of the 29th led, and then continue soldering the last group of 14 anodes together

Now solder the cathodes together, solder the first 14 together, then the next 14, and then the last 14 (see pic for clarity)

Clip all the leads and test, master + and - are shown in the picture

Repeat for the two inner Hearts, for the middle heart the number of LEDs in a group is 11, then 11, then 12 and for the small heart it's 7,7,8

Rip the tape off and use water to make the stiff paper template soggy, this will make removing the template MUCH easier

WARNING: SCIENTIFIC CONTENT
Basically, you're putting 3 groups of leds in series, which drops voltage and keeps current the same (9V - 2V - 2V - 2V = 3V leftover in each ring)

Step 3: Make the Timer

Follow the schematic:

R1= 470 ohms resistor
R2 = variable resistor
C1 = 4.7 uf Capacitor

Step 4: Make the Flip-Flop-O-Matic

Yeah, pretty much just follow the schematic again, This one's a bit more complicated.

All arrows that have letters on them DO NOT go to ground, just follow that and you're set.

I did this on a breadboard first to make sure it worked, then transferred it to perf, you could do the same if you want.

Warning: Scientific Content

The two flip-flop chips are wired to create a 4 bit shift register, this shifts a high (1) through 4 initially low (0) state bits. The high bit is shifted every peak from the timer chip. when it gets to the 4th bit the chips reset and start back at the first chip. The 2 inut nor is used to determine at what time each row of leds will light. When there is a high (1) at either input the leds will not light, but when there are no highs the leds will light. It's a simple circuit, but as this was my first time using digital logic, I am SUPER excited.

Step 5: Put It All Together!

Now that you have everything all set, take the other piece of cloth/ t-shirt and cut out a heart. You can also cut out a strip to cover the telephone wire running down to the shirt into your pocket in you want, I did. You might want to put some really thin packing foam in there too.

Sew the cloth over the leads and/or telephone wire so that it doesn't hurt your body when you wear it.

YOU'RE DONE!

If anyone actually makes another one of these PLEASE send me the pic, I really want to see your work!

I hope you liked my Instructable!