Romantic red heart

Who said that electronics can’t be romantic? We can use it to show a person our love, and it is exactly what we are going to do: a present, as simple to realize as wonderful to see, to give to the person we love. It could be a great gift for Valentine’s Day.

Let’s start: the idea is to realize a casket which has inside some little red LED arranged to form a heart shape. A switch turn the LED on and off. The device need four 1.5V AA batteries.

The final result is this:

Heart - Box Heart - Box open

Heart - On

The first thing to do is to get the necessary components:

  • a casket (the one I used was bought from Leroy Merlin, ~€2.50);
  • 27 red LED (~€5.70);
  • one 220Ω resistor;
  • one switch;
  • one battery case (4 AA batteries);
  • black cardboard;
  • soldering station (I used this one, ~€18.00).
  • moreover, it is useful to use a third hand (~€6.00) during the soldering.

Now that you have everything, we can start. First of all, you have to cut a piece of cardboard of the same height of the casket, but with a greater length: on one side, a flap will be sticked inside the casket, while, on the other, the cardboard encloses the battery case. My casket’s size is 12 x 6.5 cm, so the cardboard is ~16 x 6.5 cm.

Second step: design of the heart. Using a 2D vector graphics software (I recommend Inkscape), draw a heart, formed by 27 circles, diameter ~0.6 cm. This is the one I made:


Print it, place it on the cardboard, and make holes in correspondence to the circles: there you will place LEDs. I used a belt puncher.

The third phase begins: soldering. LEDs must be connected in parallel, that means every positive leg with the others positive, every negative with the others negative. I recommend to use a third hand and insulating tape.

Pay attention: don’t connect a positive leg with a negative one.

Most of the work is done: now you just have to connect one positive leg to the  220Ω resistance, and then to the switch (place in another hole in the cardboard). Finally, close the circuit connecting the battery case. This is the scheme:


Enclose the battery pack with the cardboard; on the opposite side, fold a little flap and stick it inside the casket.

Turn it on: it is simple, but beautiful!

Heart - On

Sorry for the bad quality of the pictures.

Stay tuned!