Friday, 29 August 2014

Scribe in a box

Digging out a bit of an oldie here, I got reminded of it as I was copying files off.

This is the 'Scribe in a box'. I play in a fantasy LARP and there's a bit of politics and the occasional episode of NPC plot exposition. Just like meetings in real life, things get forgotten if you don't take minutes.

Nobody really wants to do this and Elina found herself spending time franticly scribbling stuff down rather than enjoying herself. This was my solution.

It's a cheapo digital audio recorder from eBay, chopped around and stuck into an in character looking box. I extended the controls by carefully soldering wires to the little circuit board where the nasty metal diaphragm buttons were. I connected these up to proper switches and put coloured rhinestones on top so you could tell what they do. Likewise I fitted a decent battery holder and the AAs in there will run it for ages.

If you peer into the perforated top you can just read the original LCD display but in practice it's red button to record, green to play and when it's running you can see the little red light glowing.

This has proved very useful and is a fixture at our games now, with the recordings getting written up after the event. The only thing that is fiddly is that to get the recordings off I have to tease it apart and slide a USB cable into a socket hidden in the rat's nest of fragile switch wiring. The temptation to fix this is tempered by a worry about spoiling the look of the thing as it's really quite a nice little wooden box.

Wednesday, 20 August 2014

Did I fire five or did I fire six?

I have a working Lasertag gun! I tested the emitter wiring, found it was fine then realised I had a stupid error in my code. I've taken the Lasertag shot code Phil Higgins gave me and stuck some very basic stuff round it to make it fire with the trigger, run out of ammo and do a reload sequence. While doing some cutting and pasting I'd simply left a line out.

The gun is cosmetically a bit dodgy where I've fitted the power switch but it does work, at least indoors. Things obviously left to do are fit the sound board and speaker then if at all possible fit a USB lead so that it can be reprogrammed without taking it to bits. The LEDs on the Arduino itself are bright enough to see through the holes in the case already and act as status indicators so I don't think I need a separate one.

I want to work on the code and ideally make something interrupt based for generating the shots, but right now this will do.

The Internet of Things revolution is coming

I got my new Arduino, yay! Soon you'll be able to see whether the condensate reservoir in my cellar is emptying or not and check out the nice stable temperature all year round.


Last thing to do is mount the stack of boards in a box to keep the dust off but I've not found anything suitable. I'm using up an Ethernet shield and screw shield that I have kicking around, neither of which I can see myself using for anything else. Stacked up they make the thing quite ridiculously bulky for what it does. So it's all just going to have to get stuffed into a big box. It's not like it's going to be on show, it'll be sitting in the cellar.

It's my party and I'll solder if I want to

Today's my birthday and I didn't have anything planned so I had a soldering party instead.

I love this stuff so frankly spending a night in messing about doing this accompanied by a pizza and a couple of beers is a pretty good evening in my book.

The end result is my first ever Lasertag gun board.  I imagine it's blooming enormous compared to the PIC based ones as I've got an Arduino in there and it's all socketed up on 0.1" headers. This is deliberately done so I can mess about with it and use it as a bit of a testbed. It's been made so it nicely fills the empty space in the middle of the gun.

For power in the end I used a tiny little step-up switched mode voltage converter. Easier than messing around with funny Li-ion batteries or trying to squeeze five AAAs in there, but obviously it's not going to have brilliant battery life.

I've got the trigger and reload switches wired up, a muzzle flash working and a space for the sound board, which I'll fit another evening. It's the same WTV020SD module I've used in a couple of other projects so I'm sure it'll work OK.

Right now sadly this goes through the motions but doesn't cause Lasertag hits. It's probably just a stupid wiring error as I've used the code that's worked fine in testing and I'll debug this tomorrow night.

Sunday, 17 August 2014

The Internet of Uninteresting Things

You are looking at my addition to the Internet of Things. Well it will be once I get a new Arduino to replace the one I shorted out in a moment of hamfistedness.

All the code is written and it works but is suitably ugly, just need to wait for the new board.

It's a self emptying condensate tank for my dehumidifier with temperature and humidity monitoring. Are you excited yet? I'll be sure to provide continuous updates for everybody.

Saturday, 16 August 2014

My first lasertag gun

I play a reasonable amount of LARP where we use lasertag  as the combat system. I posted a while back about wanting to make my own gun for this and have made a start on one. So far I'm happy with the progress. Painted up like this it will make a satisfactory vaguely sci-fi looking pistol that can be used in any game where you're not fussed about having replica kit.
The basis for this is a NERF Firestrike for multiple reasons. It's a compact but chunky pistol body and has a 'laser' built in, which shines a red target on things when you push the secondary trigger. This means there's an OK lens unit, battery holder and switch all built in as it comes out of the box and like most NERF guns it's really not very expensive. Building a gun out of a decent Airsoft body is a much more expensive proposition.
Opening it up, there's a ton of space inside, I can't see me having any difficult getting it all in expect perhaps a speaker for the sounds. I'm also conflicted about powering it. The battery holder only holds two AAAs which isn't high enough voltage, I really need a steady 3.3V, preferably 5V or more. So I can either go with a step-up voltage converter or get some of those Li-ion batteries people use for vaping. AAA size but 3.6V each.
After ripping out all the NERF piston stuff the trigger got turned into a switch with a simple tactile button glued in a suitable position. I started hacking the shell about to fit an on/off switch at the rear of the gun but it interfered with this mechanism and I've abandoned that plan. Not sure what to do about an on/off switch now, I may just pop the battery cover off, it's not like tag guns draw a lot on standby.
I used a Dremel to cut the tracks on the small circuit board that connected the battery terminals and secondary trigger. This means I can take feeds separately for power and the switch, originally it just switches the batteries straight to the LED when you push the trigger. I plan to use the secondary trigger for the reload function, it's nicely placed for it and not as easy to push as you'd think.
Then I desoldered the red LED from the board in the emitter and replaced it with an IR one. It's taller so the focus may have been messed up. There will be an element of suck it and see on this.

At this point I've got a trigger, reload switch, battery compartment, emitter and muzzle flash LED ready to go which is getting it down to sticking an Arduino in there and making it work.

However I'm going to pause for a bit. I painted it last night and while I like the silver finish it's still slightly tacky. I've had this with NERF guns before, the paint seems to take ages to dry, which must be related to the solvent getting into the plastic of the body. I know from experience handling it too much will mess it up so I'll leave it a while longer to dry.

This leaves me time to sort other things on my to-do list for it like ordering some of those AAA Li-ion batteries, sorting out a suitably compact sounder, coming up with where to mount an on/off switch, making a status indicator which may just be an RGB LED and building the 'gun board'. The latter is actually the fairly easy bit.

I'd love to leave the USB programming port for the Arduino accessible if I can and maybe have a 7-segment or matrix display but I suspect the latter is stupid 'feature creep' that will drag the project out and make it unnecessarily complex.

Sunday, 3 August 2014

My love/hate relationship with hot glue.

When I built the Enigma Machine I was really against the clock to get it finished. I ended up pulling some really late nights to get it ready to go.

As a result I made some short cuts and one of them has come home to roost.

I needed to make guides for the keys so they didn't rotate and did this by hot gluing some brass flats on the end of the tubes. I never really thought this was a great idea and even as it was going together some of the joins were a bit weak.

Now over time, loads of the keys have come completely loose and the brass flats are rattling around inside the case.

So today I'm going to have a go at sorting this out. I'm not quite sure how I'll fix this. I suspect I may just switch to epoxy as the key tops have stayed on the ends of the tubes just fine with that. I'll also try to even up the keys as they weren't all perfectly the same length.