This project was originally a challenge from a friend who has some very competitive work mates. He asked if it could be cheaper to DIY a Jeopardy game system than buy one off the self and ship it to Sweden. Well the only way to check in my books is to build one, that’s my story and I'm sticking to it.
The design of the game is inspired from Chuck’s own Buzzer system. I however, have improved the hardware and made simplifications to the software to suit my needs and so that it can be run on a pro mini.
Step 1: Skill Requirements:
For this project
it would be helpful if you know how to program a micro controller. I have never used an Arduino before but the setup is very well documented online so it was fairly easy. I will add the links for the courageous first time coders out there that would like to try this.
Step 2: Tools:
PC with Arduino IDE
Side cutters and pliers
Screw driver set
Wood saw, glue and screws (for the button boxes)
Hot glue gun
Dupont jump cables male-male, male-female, female-female.
Step 3: Materials:
Living in Europe means that we have to purchase our items from China to keep the cost of these projects down. The items below are purchased from Aliexpress and the links are also here to help find them.
4x 5v relay
4x 1 meter USB cable, i think 2 meter cables are too long are too long.
Project box, if not using wood to make your own.
Wood boards or planks for making the button boxes.
Jumper wire, 0.5mm will work
Step 4: Method:
This is divided into three parts the software, the boxes and the hardware. The boxes will not be described in great detail as this is by far my worst area of expertise.
Step 5: Method: Software
I image that most of the readers should have the android IDE and drivers installed. If you are the brave one who is a first timer,head over the Arduino.cc and read the getting started section. Follow the tutorial on setting up the arduino and run the blinky exercise just to get familiar with the microcontroller. Its really not that hard to use an arduino.
The sketch code is in the txt file attached.
Open a new sketch and paste in the code form the txt file. Compile to make sure there are no errors. I used this instructrables article to upload the sketch to the pro mini.
Once the sketch is loaded into the Promini use a Bread board to connect pin 9 as the button input and pin 5 as the output. A simple button or short circuit to simulate the button press and LED to represent the output will work.
Step 6: Method: Hardware
Connect the hardware as shown in the diagram. For the electronics enthusiast im sorry but this was the easiest way to show the circuit diagram. This is were the USB 4 core cable comes in handy. You will need to cut off the one end of the connector leaving the other end able to connect to the usb ports on the rear panel plate. Strip the free end of the USB cable giving yourself plenty of room for working around the button.
Remember that all the grounds need to be connected together at a single point, even the 12v ground must be connected to the 5v ground.
Best if you install the big buttons into their enclosures first then remove the guts to do the soldering.
Replace the glass bulb in the buttons with an LED. Much more resilient to knock and bumps
Step 7: Method: Enclosure
This was the hardest part for me, I searched high and low for a cheap enclosure,tin, box. In the end I choose to make my own as it was the quickest and cheapest way to get what i needed. Why so big, compared to Chucks? Well there are cases when people are in teams so you need a big sturdy box and button, so semi intoxicated people have a chance to buzz in.
I ended up using 100x100x15mm planks and simply cutting and gluing them to form a box and then screwing on a top and bottom. The top piece has the usb cable coming in, allowing access to the switch from the bottom piece while making sure that the side opposite the button is flush to the table.
The control box was something i had lying around at, as the relays have LED's why not have a see through cover as well. This enclosure was also made of a thin plastic thats designed to be easy cut.
As seen in the photo of the control box the USB rear panel plate has been ground down with a dremel for a cleaner look. I also needed to replace the original screws holding in the usb connector with slightly longer screws
To keep the box small and cables numbers to a minimum i soldered common grounds and supply voltages together on the relay. As well as adding plenty of cable ties to keep it tidy. I also covered the soldered joints with hot glue to help against mechanical stresses.
Step 8: Connecting It All Together
Connect all the usb cables to the controller. Start pressing buttons, and have fun.
I found two problems when it came to this stage. The first was that i had relay chatter. I tried to use a 2A, 5v usb charger then step up the voltage to 12v. Chatter is when there is not enough current for the application and the voltage drops below the allowed state for the relay so it opens, the voltage builds up again and the relay closes, repeating the process over and over. To avoid this use the ratings of the 12v/5v supply i recommend.
The second problem i had was that when i pressed button 1 the light for button 2 would light up. This was simply a wiring problem, if all else fails pull all the wires and connect the inputs and outputs one by one to ensure the right light comes on when the button is pushed.
Step 9: And Your Done
If all has gone well your system should work the same as this one in the video.
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