LED Umbrella with Arduino

Step 6 Making the LED Matrix -- Cathode Chains

The first step in making the LED matrix is to construct the chains for the LED cathodes. In the previous step you cut ten (or the number of ribs on your umbrella) black wires and stripped the insulation at the points where the LEDs are soldered. In this step you will solder the cathodes of the LEDs.

Get a small blob of solder on the tip of your iron. Position the LED so that the wire passes between the two leads of the LED and apply the hot iron to solder the cathode. The solder on the iron and the wire should flow to make a connection. You will burn your finger and they will taze you. After soldering, trim the anode so that it is as short as possible.

To prevent short circuits, each solder joint is covered with a piece of heat shrink tubing. The tubing has to be applied after a connection is made and before the next LED is attached (any confusion? you will soon understand :-) so slide a piece on now. Heat to shrink into place.

Repeat for the remaining LEDs in the chain and the remaining chains.

Note In this instructable, the chains of LEDs that follow the ribs of the umbrella are referred to as columns and each terminates on a pin of the Arduino. The LED cathodes are soldered to these (black) wires. The rings of LEDs that circle around the umbrella are referred to as rows and each begins at one of the MIC2981 output pins. The LED anodes are soldered to these (red) wires.