Hi, this is Wayne again with a topic “LED Matrix Dessert Tray”.
This week, I am going to show you how to make a LED matrix, dessert tray.. This will let you light up and animate your cakes and other snacks.. The first thing that you need to do is build a large, LED matrix. Start by cutting out a 10 inch by 10 inch square of card stock and dividing it into a grid of 2 inch squares..
Next, we need to attach a set of LEDs in each square. To do this, take a pin and make two holes for the leads of each LED. Then insert the LEDs so that all the cathodes are on one side and the anodes are on the other..
We need the LEDs in each square to be connected in parallel., So I bent the cathodes in one direction and I bent the anodes in the opposite direction., Where they overlap. I soldered the leads together and wrapped them in heat shrink tubing.. Now we need to connect the individual squares together into rows and columns.. First, I connected the anodes in each row, together with a large piece of copper wire., Then I applied tape over it to help insulate it..
Next, I connected all the cathodes in each column, together. And I applied more tape to insulate these connections.. You should now have a functioning LED matrix. To test it. Take a 3V battery pack and connect the positive wire to one of the rows and connect the negative wire to one of the columns..
The LEDs in the intersecting square should light up. To help keep the light in each square from diffusing into the adjacent squares. I added a set of dividers that I made from folded paper. Now you need to construct the plastic cover plate that will hold the dessert. To do this.
I started by cutting out a 16 inch by 16 inch piece of clear plastic.. Then I cut some 3 inch wide pieces of foam board and glued them around the outside.. When you are done, the cover plate should perfectly fit around the LED matrix.. The last thing that you need to do is setup a control circuit for the LEDs..
I am using an Arduino microcontroller.. The easiest way to use an Arduino to control an LED matrix is to send a HIGH signal to the anode and a LOW signal to the cathode.. This will turn on the LED..
Unfortunately, the LEDs that I am using require more power than the digital pins can output.. So I am using a set of power transistors to control the switching.. In this configuration I have an NPN transistor connected between each set of cathodes and ground and a PNP transistor connected between each set of anodes and the positive supply..
The base of each transistor is then connected to the digital pins, with a 1 k resistor.. Now your LED matrix, dessert tray is complete.. All you need to add is the dessert.. The best things to use are snacks that let a lot of light through such as white cake or rice crispy treats.
Set your dessert on top of the tray and turn it on.. There is a link in the description box where you can download some example code to animate your LEDs.. Well, that is how to make an LED matrix, dessert tray. Thanks for watching .