Arduino Report #9: Project 11--Model Traffic Signal Using a Rotary Encoder

Additional Parts:

1. Green LED x1
2. Red LED x1
3. Orange LED x1
4. 220 Ohm x3 
5. 100k Ohm x3
6. Push-to-make switch x1
7. Rotary Encoder x1

Time to Complete: 45 min

This project is very similar to the Model Traffic Signal I wrote about before. The difference is that a rotary encoder is introduced to control the frequency at which the lights change. A rotary encoder is a knob that with two output pins that can be used to determine if it was turned clockwise or counter-clockwise. Unlike a potentiometer, a rotary encoder can be rotated indefinitely. They are commonly found employed as stereo volume knobs. Many rotary encoders also incorporate a push-to-make switch built into the knob. Unfortunately, I did not read closely enough when I was ordering new parts so my rotary encoders are buttonless. However, I did have a push-to-make switch in my box-o-parts, and with a little modification, I was able to complete the project with total functionality. 

This project was not without its small hangups. I quickly broke the output pins on the rotary encoder trying to put it into the breadboard. As a result, I ended up soldering wires onto the nubs where the contacts were. This ended up being advantageous in the end as the rotary encorder can now sit away from the tangled mess of the breadboard. I was able to quickly determine, from the data sheet from the rotary encoder and from my previous experience with the push-to-make switch, how to adjust the circuit for the buttonless rotary encoder. The circuitry is above and the video is below. Pushing the button turn on all the lights simultaneously. A clockwise rotation of the encoder slows down the light change rate while a counter-clockwise turn speeds it up. Again, the traffic light pattern is in the UK style.

Next project will probably be the Keypad Security Code or one of the more advanced LED displays depending on when the Mouser shipment arrives. I'm still waiting on a few transistors. 

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