Flashing LED Heart DIY




Introduction: 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.

Step 1: Parts, Materials, Tools, the Usual

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


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


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


Plastic container for ferric chloride

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


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

Step 2: Preparing the Circuit (testing)

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

Step 3: Making the PCB

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

Step 4: Making the Faces of the Casing

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.

Step 5: Making the Array

  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.

Step 6: Putting the Inside Together

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.

Step 7: Last Up, CASING!

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

Step 8: Finished

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! :)

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4 Discussions


4 years ago

Hello. :) I just check your file uploaded for the schematic, and the site suggest that it was removed. Can you please, kindly upload it one more time? I'm very interested in this idea for our project. Thank you in advance!


5 years ago

Are the leds brighter at the upper left part of the heart or all the leds have the same brightness? I cant see clearly. And Im not so good in electronics but you pointed out a series of LED while you connected them in parallel? What should I prioritize? Should I connect them in series to have same current or in parallel to have the same voltages? I so like it!


Reply 5 years ago on Introduction

All LED's seem to have the same brightness (not very bright though, because of low amperage). Now how you connect them depends on your voltage, as if you connect them in series, the voltages must add up (in this case, there are 37 LED's here, each led needs ~2.5V, 2.5V*37=92.5 VOLTS, good luck fitting that in a small casing :D). But if you wire them in paralel, the amperages must add up, and a under-amperage just affects the brightness, but they still work. Sooo always wire them in paralel, as you wont get portable 93 volts, unless you have strong arms and nothing to do :).