MSRaynsford

  The knife switch is housed in one of the corner columns from the box, it builds upon the corner column framework . This is the most complex of the four corners because this one is locked at the start of the game and needs to be opened before the switch can be flipped. On the original box I guess I just glued some bits together until it fitted and worked, now that I'm building ten I actually had to take a bit of time to get my files in order and I also a redesign to make the geometries work out. There are lots of individual parts that go into this corner, captive nuts at the top and bottom to mount it in the box. Another captive nut for the locking key and all the separate fingers that go into the hinge joint. The fingers on the lid were cut from 2mm ply to allow plenty of space between the 3mm fingers of the box. Solder lugs were attached to the screws of the knife switch to provide an easy way to solder wires to the switch when required. The flap that closes over the knife switc...

I really felt like this box needed to be turned on with a knife switch. With me not being so good at metal work this means finding something commercially available. All I could find in an appropriate size and material were these plastic single throw switches, which means converting them to double throw and creating some wooden bases for them. First these horrible things need to be dismantled.  Most of the pieces are screwed in but I needed to dismantle ten pairs so even that takes a while. The brass parts are riveted in place so they needed to be drilled out. The holes in the brackets also needed to be drilled out to a mm larger to accommodate the screws that I want to put in instead. Ten sets of knife switches all prepared and ready to go into the boxes. Interestingly these things need two digital inputs and tie in nicely to the current stage of the tutorials. The other interesting thing is that you need to prove you're 18 years old before you're allowed to buy knife switches ...

I said we'd take a little detour to make a fully functional puzzle using our two buttons and two lights and so I present to you, a Binary Puzzle. I have made two binary style puzzles before, one was purely mechanical , and the other one used a cabinet lock and a series of switches to activate it (but no blog post). Both of these are simpler ways of making the same puzzle so we need this to be different somehow. Since we have the full power of a microcontroller why not make the codes change over time. Every time you fail to enter the code correctly it will change the code, so let's dig into the system. Hardware wise it's a bit ugly, all of the information required to solve the puzzle is contained on the front of the panel which could be mounted in a box or in a wall. The reverse is just enough hardware to hold everything in place and some basic soldering to recreate everything on the previous prototype board. Two switches connected to D5 and D6  using the internal pull up...

In this tutorial we're going to talk about fading an LED from On to Off and back again but I think it would be really useful to have two LED's to fade. This means a short detour into setting up LED's and most importantly current limiting resistors. Most modern microcontrollers are capable of supplying enough power to directly drive an LED, meaning you can connect an LED to an IO pin and directly turn it On/Off. There is a limit to how much power the pin can supply and also how much power the LED can take before one or the other will burn out. You should never connect an LED directly to a power source, you should always have a resistor in line with it to limit the maximum amount of current that can flow through it. To calculate the exact amount of current flowing through a circuit you need to know Ohms law .  Voltage = Current x Resistance .  We're using a 100 Ohm resistors in this circuit, so if it were connected to 3.3V output on the GPIO pin the current would be 3.3/...

I use radiator bleed screws with a square end and radiator keys to secure one of the compartments on the side of the NikolAI box. The screws themselves have a tendency of disappearing all the way inside the keys which can make it really hard to close the compartment again. The simple solution is to pack the inside of the key to prevent the screws from moving too far inside them. The small pieces of packing material had a tendency to fall through the honeycomb on the laser cutter so it was easier to affix them all to a sprue and snap them off as required. This allows me to lift the whole thing out of the laser cutter in a single piece and not lose any of the tiny squares.

  We picked up a super cheap copy of Cobra Paw from an outlet store a few weeks ago. I'm honestly not sure how they managed to acquire a dozen water damaged German copies of the game but having played the game before I realised it was totally worth the 50 pence I spent on it. The default box has always felt oversized to me but I guess that's something about perceived value. It prompted me to make this much smaller wooden box for the game which sits much nicer on our game shelf. The rules are simple enough to not actually need a physical copy of them. ( svg here )

Yesterday's post showed the making of this little two button remote control  so it seems only right to to include it in this post about reading multiple buttons. It's just two simple buttons that pull the data line down to ground when pressed and could easily be recreated on the breadboard if required. We're also going to talk about multiple LED's and set up the framework for using multiples even though the we're only going to using the one built in LED again. The main difference between this program and the previous one is that the inputs and outputs are going to be defined as arrays of values instead of just single values. Right at the top of the program it's important to define how many inputs and LED's there around going to be and then create an array of values to declare which data lines these things are going to be on, in this instance D1 and D2 and the same LED as before. even though there is only one LED we can still define it in an array. Now when...