Heart-shaped LED Freeform Circuit

In this project, I'm presenting my first attempt at building a freeform circuit sculpture, out of soldered brass wire and a few LEDs. Since it's February, and the LEDs I had laying around were pink and heart-shaped, my sculpture is Valentine's day themed.

Freeform electronics is a style of making electronic circuits in a way that is not only practical, but aesthetically pleasing as well. The entire structure is made out of conductive brass rods soldered together, allowing every circuit connection to be visible. Like many others, I am fascinated by the wonderful works of art created by Mohit Bhoite, and I got inspired to try the technique myself. While he makes some things (like soldering the perfect straight rectangles) look deceptively easy, I am very happy with how this turned up! 

• Uncoated brass wire 0.8 mm (20 AWG)
• LEDs - I used these sewable hearts from Teknikio 
• CR2032 battery holder (it can be created out of wire, but I used a sewable one)
• Alligator clips
• Wire cutter
• Pliers
• Soldering tools: iron, solder, heat resistant mat 
• Tape 
• Printed template, or pen and paper to draw one
• Ruler
• Optional: tracing paper (I stole a rainbowy sheet from the unicorns!)

In this project I'm creating a very simple electrical circuit, 8 LEDs connected in parallel, powered by a single 3V coin cell battery.

The LED breakouts I am using are designed for sewable projects, and can be powered directly by a 3V battery. For that reason, I can skip including the usual resistor between the power supply and the LEDs.

Having a template makes it easier to bend the wire in the desired shape. The template can be either printed, or alternatively, drawn by hand, like I did while planning the layout. 

I decided on a heart shape, made out of 2 halves, with the LEDs evenly spaced along the contour.

Symmetry is important (so are rainbows!). I used a piece of tracing paper to create symmetric halves of the heart shape.

In my design, one of the halves represents the positive side of the circuit, and the other one the negative side. Each LED is connected to both halves, keeping the correct polarity. To complete the circuit, each half is connected to one side of a battery holder. 

When the battery is inserted into the holder, all the LEDs turn on, and stay lit until the battery is removed, or depleted.

If the brass wire comes on a spool, like mine did, it needs to be straightened before using it. There are various techniques to do so, I used the one demonstrated by Mohit in this video. I cut two pieces of wire in the approximate length of the two half hearts, with some length to spare, and used a power drill and a pair of pliers to straighten them. 

I placed the straightened piece of wire on the paper, following the template traces, bending it when needed with the pliers, then fixing it in place with pieces of tape. I used single sided tape, but double sided tape might actually be easier to use. I will try that in my next project.

I repeated the process on the other half of the design.

Next I soldered the 2 ends together for each half of the heart, to keep the shape of the wire, and attached the first LED with the positive pin to one joint, and the negative to the other. I then soldered the second LED at the bottom corners of the heart shape. The two LEDs form both an electrical connection, and a mechanical one, keeping the two halves of the design together. 

The wire needs to be precisely cut, so the two ends do not overlap, but form a continuous piece while soldering them. 

In retrospect, creating a solder joint exactly at the corner of the design, and where the LED needed to be placed, made my job harder. For the next project I will try placing the meeting of the 2 wire ends somewhere in the middle of the straight line in the design.  

Soldering the first 2 LEDs did get a bit messy, especially as I was figuring out how to not burn the paper, while keeping everything in the correct place, but it worked out in the end.

Warning: the brass wire does get very hot, very fast, while soldering, so use pliers when holding it in place!

At this point it is a good idea to do the first test. Red alligator clip is attached to the left half of the heart (positive side of the LEDs), and the black one to the right half (negative side). Connect the battery, and the soldered LEDs light up, yay! 

Since the circuit can keep its shape at this point, it can be removed from the cocoon of tape keeping it stuck to the paper. I first made sure to mark the spots on the wires where the other LEDs need to be placed in the design.

Placing the circuit on the heat resistant mat, the rest of the LEDs can be soldered on. Three of them are attached by their positive side to the left half of the heart, and the other three by their negative side to the right half.

To complete the circuit, the LEDs need to be connected to the other halves of the heart as well. I cut pieces of wire to size for each LED, and bent them at 90 degrees in 2 places, to create a bridge over to the other side. Since brass wire is pretty stiff, it will keep its shape, and the risk of short circuits is pretty low.

I kept testing at every step, until all the LEDs were connected and lighting properly. The hardest part is over! 

...or so I thought. 

Hardest part turned out to be building some "simple" wire rectangle 3D shapes for the base of the sculpture. 

I tried both building the shapes out of precisely cut small wires fixed in place with tape, and bending one long wire in the desired shape.

Each method has its challenges, but I succeeded in creating the two box shapes I needed. 

For the next project I will try to build a 3D template in the needed shape, and attach the small wire pieces to it with double sided tape. That should help keep the wires in place while soldering, and help maintain the 90 degree angles.

Each box was soldered to one side of the battery holder, so basically one box ended up as a positive side of the circuit, and the other the negative. Being careful to keep the correct polarity (positive from battery to left part of the heart, negative to right), each box was connected by a vertical wire to the correct side of the heart shape.

And with this, the project is done. Battery can be inserted into the holder, and let there be (pink, twinkly) light!