In this tutorial you will learn how to make a weighing scale that visualizes its current weight through the use of an LED RGB strip. As a team we wanted a way to educate the public about recycling and incentivize them to recycle more, and in return help reduce the environmental impact of nonrenewable resources. We wanted to solve this problem through this system we are building.

Step 1: Gather Materials

Here is what you will need to complete this project:

1. An Arduino Uno

2. A 12v power adapter for the Uno

3. An LED RBG strip

4. Weight sensors and a load cell

5. Soldering materials

6. Cardboard box

7. Newspaper

8. Wood

9. Wire for connecting electronics

Step 2: Soldering

Follow the fritzing diagram to make sure everything is soldered together correctly. Make sure you use different colored wires to keep track of everything. Soldering to the load cell can be difficult because it is pretty fragile, so be gentle!

This circuit basically works by the four sensors working together, each getting their own signal. This signal is then sent to the load cell which converts the signal into weight that is used by the Arduino.

Step 3: Put Electronics in the Electronic Box and Mount Sensors.

Once you have the wood cut to the size you want, mount the sensors. Make sure that the weight sensors are being properly bent in order to receive the weight signals properly. We used a 3D printed foot, but you can use anything that elevates the outer ring from the inner part of the sensor so it can be pushed down. Store all the cable in a box under the scale.

Step 4: Big Box Construction

You can use whatever you want to hold the garbage can. We opted for an outer receptacle made from cardboard and decorated in newspaper. Similarly, the lid is just a box with a hole cut through it.

Step 5: Attach LED Strip

Cut a hole through the lid to feed the LED strip end through. Alligator clip the exposed ends to some wires to connect to the arduino in the appropriate pins.

Step 6: Upload the Code

Follow the link here. Copy this code into the arduino IDE. You may want to change the goal weight to turn the light green to your preferences.

The code basically is a nested conditional statement where different conditions send different LED outputs. If no weight is on the scale, it is displayed red. If there is some weight, it will be a color from a gradient between red and green depending on how much weight is added. When the goal weight is hit, it displays green. Simple.

Note: You may have to install the library in order to use the functions for the scale. That can be found here. Use this if you don't know how to install libraries.

Load the code onto the arduino. Make sure the connections are sound, and it should work!