Electronic Quiz Game

This is kind of an old project. I'm not the first to describe something like this and even way back then, when I was 12 or 13 years old an built this, I had my very clear inspiration. My grandma had such a game left from my uncle and I'm sure we could have taken it with us, if we had asked nicely. But building one myself (I was the hardware-guy) seemed way cooler. And it was.

I was quite unsure, if I should even describe such an old project. But back then I was quite proud of it and I still like it with all it's flaws. But above all, after years of slumber in a cardboard box I took out the prototype of the upgraded version and finally completed it. And it came out quite marvelously. So I want to make a instructable, when I put together the next one and it might be easier to explain, if I can just put in a link to the original project, so everyone can have a look where it came from.

Technically this simple game is a very simple decoder. If you connect the fittiing letter-number-combination a LED will shine. That's all there is. In combination with quiz sheets it becomes a game. There might be the picture of a Lion with the number "1" alongside some other numbed animal pictures and a list of the animal names like Lion "K", Tiger "C" and so on. If you connect this numbers and letters you can check if your guess was right.

My siblings and I made a whole folder of such quiz sheets. So they get the next upgraded exemplars I build. Yeah, they are kinda old for such games but you can always hope for the next generation.

• two boards of ply wood or MDF (420x310x3 mm ply wood for the game, 428x248x3 mm MDF in some example shoots to demonstrate the building process)
• 1.5 to 2 m of 20x20 or 25x25 mm square wood (the thickness of the square wood and one of the boards combined must be more then the mounting depth of the sockets or buttons)
• 54 banana sockets and two banana leads (4 mm) or 52 buttons
• a 5 mm LED (green) with socket and series resistor
• a battery holder (e.g. for 2x 1.5 V Mignon or Micro Batteries or a one 9V Battery)
• some wires
• solder
• wood clue, nails and screws
• spray paint (if you want to color the game fast)

Tools

• power drill and drills
• saw
• soldering iron and wirestripper
• center punch and hammer
• screw driver

Way back I made a lot of pencil lines on the ply wood to mark the positions of the many holes I needed. Now I would plan it out on a sheet of paper, fix it nicely centred on the board and mark each crosspoint with the centre punch. If you drill holes in wood, the top side comes normally out nicer. And I don't want to ruin the nicer side with all these lines.

Since we have 26 letters and 26 numbers I went for two lines of 13 respectively. The distance between second and third line is slightly larger to separate letters and numbers. In the top middle position the LED will deliver judgement over the answers. To it's left and right there are sockets for the fixed positions of the banana leads.

When all positions are marked you can remove the paper and drill the holes. Pay attention to the LED hole, you might need a different diameter for that one so it might be a good idea to start there to not get it done with the wrong drill in the heat of the moment.

For the frame I used 20x20 mm square wood. It's kind of a tight fit with the sockets so 25x25 mm might have been a more reasonable choice in combination with the sockets. Saw the the wood to the fitting length and fix it to the front panel with some wood glue and/or nails. I used both. Way back I made some plain 90° cuts (or more like 85° cuts) but with a quite primitive fixture you could make 45° mitre cuts to make it look even nicer. Or maybe you own some fancy circular saw.

If you want to paint your game, now is the time to do it. You don't want to paint the sockets and the LED as well. I always do this in the backyard to get enough fresh air and use a big flattened cardboard box as underlay so I don't end up with coloured turf.

Maybe you have some old game, possibly not working anymore, and want to make your game compatible to reuse the old quiz sheets. Otherwise it is way more fun to generate a code than to copy one. If you own a scrabble game it makes a great lottery. Just put a tile with each letter in a bag and draw. The first letter you draw will be related to the number of one and so on. Write it down to a list right away.

If you don't have a scrabble (or can't find it) you can write down the letters to small pieces of paper or cardboard or use the keys of an old keyboard.

All you need are some simple electrical parts. Okay, quite a few of the sockets or buttons. Way more, than I could throw together for the picture. As far as I remember 50+ sockets of the same colour were slightly cheaper so they are all blue. But different colours for the letters and numbers and maybe a third colour or uninsulated metallic sockets for the fixed lead ends might make a more interesting design.

The sockets I found for the picture have a metallic thread so you could clamp the wire between the nuts. That would make way less soldering. Just make a eye at the end of the wire and put it around the socket in such a way, that it get's tightened as you tighten the nut. For my game I had to use the soldering tags. I'm still not very proud in my soldering skills, but it seems that I improved a lot.

In the original game i used a 9 V battery with a simple clip and fixed it with some tape to the front panel. It might not be the prettiest solution, but it works. Now I would go for a battery holder with two 1.5 V batteries as I used in later projects. Why? The LED has a built in potential of circa 2 V so if you use a 3 V voltage supply the series resistor will convert less electrical power to heat.

Since the built in potential of the LED is 2 V, the potential difference at the resistor is 1 V if we use the 3 V supply and 7 V if we use a 9 V supply. The LED can handle up to 15 mA. This values we can use to dimension our resistor. It has to be at least:

• R_9Vsupply = 7V / 15 mA; R_9Vsupply = 467 Ohm
• R_3Vsupply = 1V / 15 mA; R_3Vsupply = 66,7 Ohm

There are many resistors to by, but you won't get one of these exact values. So go for a slightly higher one. That will result in a slightly lower current so your LED won't get damaged and still shine bright enough. 470 Ohm are very common, as they are part of the E3 series (3 values of resistance per decade - a decade reaches from 1 to 10, 10 to 100, 100 to 1000 and so on). But even for a resistor with +/- 1% tolerance, it is a little close to 467 Ohms, so you might want to go for a 560 Ohm resistor (E12 series) or 510 Ohm (E24 series). In case of the 3 V supply 68 Ohm are a common level (E6 series) an okay with a tolerance of +/- 1%. For the picture I chose a 73,2 Ohm resistor, a more exotic guy out of the E96 series. I got a load of those with a cheap kit of seldom sought after resistors. For my original game my uncle got me a 499 Ohm resistor (E96 series) which goes well with the 9V supply. So he did the dimensioning right.

If you want to be well equipped for tinkering and own your own kit of resistors, I would go for E6 or E12 series. Even if the higher series contain all resistors of the lower (or some pretty close to those) you get less of a kind and only the exotic ones will be left at some point.

Furthermore there will always be ranges of values you need more frequently. In my case those are 100 Ohm to 1 kOhm (serial resistors) and 10 kOhm to 47 kOhm (pull-up and pull down resistors) so I restock the values I need more often whenever I run low.

The current can only flow trough the LED in the one direction so the longer leg must point to the positive pole of the battery, the series resistor may be on whatever side of the LED. When the banana leads connect the correct socket-combination to the fixed socked or if the fitting buttons are pressed, the circuit has to be closed. So If you are unsure follow the wiring as depicted. The LED symbol is shaped like an arrow. It points from long leg to the short leg.

Connect all the sockets representing numbers and letters according to your code. Each letter has to be connected to exactly one number. It helps a lot to label your sockets on the backside of the panel with pencil in backwards order so the connections are in order, when the game is flipped.

If you want to use buttons, chose closing buttons as they shall close the circuit when they are pressed. They have two pins. You can connect one pin of each number button respectively and do the same with the letter buttons. These connected pins you can now connect to the wires, that would lead to the fixed position sockets. Now you can connect the free pins, as you would connect the sockets.

You can try to do your wiring in a less messy way, than I did. A nice and tidy wiring harness would be perfect.

A game painted in green and featuring yellow and blue buttons could look like this. Label all sockets or buttons with there respective letter or number in a readable way. I just used a black marker. If you use sockets, put a end of one banana lead to the socket left to the LED and a end of the other lead to the socket on the right. Now you can check your combinations. If something went wrong you have to fix it

Screw the second board with a few screws to the bottom. You want to be able to open it again, when the batteries are discharged or the wiring loosens, but the sockets don't feel good, if you put the game on your lap, and the wiring might get damaged over time, if there is no base plate.

Now you can create quiz sheets (our folder is like an evolution of printers archive) and enjoy the game.