This is a guide on how to build really inexpensive and attractively looking Quiz Systrem based on hacked wall lights and Arduino board. The video demonstrates designing and assembling process and if you find it interesting please welcome to the next page for more technical details!
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Step 1: Finding and Hacking a Pushbutton
This time our task was to build a Quiz System (also known as ‘Quiz Buzzer’ or ‘Quiz Show’). The real challenge was in meeting two major requirements: being really inexpensive and looking attractive and ‘factory-made’ at the same time as the project was intended for use in elementary school. To our surprise, it became almost next to impossible: when it comes to a pushbutton combined with a bulb or a LED, large enough to be pushed with a palm the price climbs unjustifiably high even for a single button. Given that our project was envisaged to be used by up to six participants the overall cost per unit looked really bleak. And visa versa, cheap (or at least affordable) buttons available at online electronic shops looked too simple or even ugly. That is why we turned our attention to doorbells hoping to find big and reliable buttons. Again, without any success as there is a tendency to shift to wireless doorbells because apparently selling just plain buttons is not a profitable business anymore. We began wandering around visiting numerous local shops looking for something that could work as a pushbutton. And all of a sudden a battery powered wall light in a Chinese shop caught our attention – it looked like a button but at the same time it had a round dome which was illuminated by a bulb just like we needed! But most importantly it had a price tag of just $2! The only problem was that it acted as ‘push and hold’ instead of just ‘push’. In other words, first push switches the light on and in order to switch the light off it has to be pushed again. We decided to take a risk and bought one light to see whether is was possible to convert it to a ‘pushbutton’. As it turned out it was an easy task to do the modification so we rushed and got five more as it is shown on the picture below.
The process of disassembling and conversion of 'push and hold' to just 'push' button is shown on the video in the previous step.
Step 2: Wiring Up
LEDs and buttons wiring up is rather asсetic and doesn’t require advanced soldering skills. LEDs are connected as common cathode so they share common ground with buttons. Each pushbutton needs three wires, one for button, one for LEDs and one for ground. The given example uses Arduino Mega2560 w which is a little bit overkill for this project and technically speaking virtually any other Arduino board can be used with minimum changes to the wiring up.
Step 3: Arduino Sketch
The Arduino sketch provided in the attachment shows that the application is really simple: it initialises 6 pins in PWM mode to control LEDs and 6 pins in input mode to read button states. Any change on button inputs triggers an interrupt so that it allows to handle all six buttons independently and without priorities, all users are given equal opportunities. Upon bootup the system enters demo mode when all buttons are lit up sequentially and any button press toggles the gaming mode. In gaming mode a system first waits for a button press. Button which happens to be hit first is illuminated for a few second and the the system is ready for the next round.
Step 4: Conclusion
What is more important, the system has plenty of resources unused and this project can be looked at as a template for more advanced and sophisticated designs. For example, it can be integrated with a PC via USB interface so that the device can control Power Point presentations for instance which would navigate to certain pages depending on user input. Another possible enhancement is addition of a RC interface for master control or a small graphic display to indicate winner number – all those small things which would make children interested in gaming process or maybe even in electronics & programming.