Spring 2016 3DOT Making Laser Tag Possible: The PCB Layout.

By: Kevin Moran (Electronics and Control Engineer)

For Fall 2016’s 3DoT Goliath it was my job to design from scratch a printed circuit board that would allow our rover to emit and IR signal, and also process a receiving signal. This process started as a messy image on my notebook, and was later processed into a cleaner Fritzing diagram. The diagram for the circuit changed as the weeks progressed due to help from my division manager, and my attempts at making this circuit better each time.

Testing:

Before processing to order the PCB a good amount of time went into testing the circuit below. I had to ensure that the capacitors used for removing the unwanted AC components from the power source were doing their job. I spent many hours testing various resistor sizes in order to ensure that the voltage thresholds were the correct ones with our 5V voltage supple. Once I felt sure of my decisions I moved to the next step, which was to design this circuit on Eagle CAD, in order to have the manufacturing engineer design the PCB board and order it. By this point, I already knew my emitter/ receiver combo worked, and that using the Schmitt trigger I was able to clean this analog signal and convert it to a single bit digital signal.

PCB Layout:

As can be seen below, all of the components are named, and have specific values. These values were obtained during the testing stage. All components of the circuit are properly grounded and given access to the power supply. The Piezo buzzer is hooked up to the 220 ohm speaker to regulate it output level. All other resistors were calculated to ensure the circuit works properly.

Note: If you are reading this, you will be provided with access to my Eagle Cad, and Fritzing diagram files, hopefully the next generation rover has an easier time.