Flashing LED Heart DIY

A series of 10mm L.E.D.'s placed in a heart-shaped wooden box that flash using a 555 timer with adjustable flashing speed powered by a 9 volt battery. I got this idea, because i was thinking of a gift to my girlfriend on a special occasion ;), and this gift really pleased her. It is not a hard project, nor to expensive, but it requires some experience in electronics, soldering and woodworking.

There are alot of things youre going to need for this, so get your pen and make a shopping list.

THE LINKS I AM GIVING YOU ARE EXAMPLES OF THE PARTS, YOU CAN BUY THOSE ONES IF YOU WANT, BUT THEY MAY COME IN TOO LARGE QUANTITIES.

Electronic components (you will find these all online or at your closest electronics store)

Any 555 timer http://adf.ly/pUFSM

37 red LED's http://adf.ly/pUG7l

1K Ohm resistor

220 Ohm resistor

500K Potentiometer (variable resistor) http://adf.ly/pUIji

1uF capacitor (>9V)

some wires

9 volt battery

9 volt battery holder http://adf.ly/pUIuh

Optional: 2200uF capacitor (if you want a smooth transition between blinks)

A switch

Materials

Wood sheets (i used 4mm thick)

Glue (hot glue recommended)

Electric tape

Solder (1 mm best) http://adf.ly/pUHna

Copper PCB (for holding the LED's) http://adf.ly/pUHgT

Ferric chloride (for PCB etching) http://adf.ly/pUJBV

Acetone

Plastic container for ferric chloride

Fresh PCB board http://adf.ly/pUMWb

Tools

Soldering iron

Hot glue gun (with plenty of glue)

A dremel would be very handy

Tools for cutting wood (saw's, disks, you know)

Breadboard http://adf.ly/pULQR

PCB marker http://adf.ly/pUMaC

To make sure the circuit will work, we must build it on a bread board first.

There are many ways to make PCB's, but the method i use is wither toner transfer or drawing the traces on the board with a PCB marker.

Here are the schematics for either:

Toner transfer: http://adf.ly/pUTct

Drawing with PCB marker: http://adf.ly/pUTlM

1. Download the PCB layout i supported above, i drew mine directly on the board with a PCB marker (see photos) but you can print the schematic onto glossy paper, using a laser printer, and transfer it to the board with an iron (look up toner transfer method)
2. Once the layout is on the board, put it in a container with ferric chloride and water
3. Wait for it to finish etching (~15 minutes, faster if you use warmer water)
4. Use acetone and cotton pads to wash off the resist
5. Drill all the holes
6. Put the components inside the holes
7. Solder the components
8. Solder wires for battery, potentiometer and output
9. ??????????????
10. Profit

Get ya power-tools and prepare to cut!, but wait, before that, you need to carefully plan out the size and shape of the casing. First of, you must remember, that the LED's are said to be 10mm, but thei have a small widening ring on the bottom that make them 11mm, so this is crucial for the layout, learn from my mistakes. I made the layout out of 11mm cubes for it to look better with the "11mm" LED's.

1. Get the copper circuit board and size it to match the hole on one of the faces (leave some extra over the edges so its easier to glue)
2. Start placing the LED's tightly to each other (they are not going to fit well, so you need to get a drill and expand the holes that you have places the LED's in)
3. solder all the anodes together and all the cathodes together.
4. Place the array inside the face as deep as you can and youre finished with the array.

Pretty straight forward i think, just connect all the wires where they belong, isolate the array's pins so you can place the circuit on it, put the battery holder on the back, install the switch, install the potentiometer.

Cut out a s**t load (count how many you need) of 35x11mm wood planks and start placing them around the face.

Just glue the back on it and pull that switch :)

Adjust the speed by turning the potentiometer, happy valentines day, anniversary or birthday to your loved one! :)