There’s a running joke amongst my friends that I’m an actual time-travelling mad scientist – mostly because it’s more true than false. So I figured, why not run with it a little and have some fun with it. So that’s what I’ve done here – I’ve restored this old Mad Scientist’s Knife Switch into perfect working order!
Safety is important – especially when you’re going to have “exposed” bare copper like I have here. In this case, the exposed bare copper is only ever running at 5 Volts, and those +5V connections are used to open/close various relays. You can even lick the bare copper if you wanted without feeling so much as a tingle.
Fully restored/repaired/running, this knife switch is now sitting around my house as a random extension cord you can use to turn on any appliance that you plug it in with.
My DeLorean‘s now 39 years old, which means it’s got a long list of “nice to haves” that either need some attention or just outright need replacing. One example is the foam in the door upholstery – that collapsed into a black powder a long time ago and left the doors completely flat, hard, and with no depth to them. So let’s fix that! DeLorean Go offer a Door Card Foam Repair Kit with what you need. Since I’m in Australia I ordered the kit with the two tubes of glue instead of the tin of glue. I personally would’ve found it better to use 3 tubes of glue and I would recommend you buy 3 just in case, but you can definitely make do with just 2 tubes.
As far as jobs go this one is more fiddly than actually tricky. There’s a trick to popping the doors out that involves having the window down while you do it, and make sure you completely vacuum out the old foam dust from all the pockets. It’s also important to keep the vinyl stretched taut over the backing piece as you work, and also apply the glue to both surfaces and let them dry a little bit before pressing them together. Finally, this is a good time to replace your door’s fir tree fasteners if your old ones have gotten all mangled up.
The end result should look something like this – the extra curves & shaped definition in the vinyl are subtle, but definitely there and make it look that little bit better!
My wall clock in my house recently died, and with there being a running joke that I’m a time traveller thanks to my DeLorean, I thought I might as well build a replacement clock myself so it could be extra unique. Here’s what I came up with: a self-setting, self-correcting, self-adjusting wall clock/chronometer that tells time both in our timekeeping system and in the 25-hour D’ni timekeeping system used in the Myst series of video games. This is actually pretty handy if you want to know if it’s the right time to log in for certain events in Myst Online: Uru Live.
Technically it’s more a “chronometer” than a “clock” – the main difference between the two is that chronometers have far higher accuracy & precision, to the point that they can be used for scientific experiments. For this one, it’s generally safe to assume it shouldn’t read outside 0.003s of the actual time, but in practice it’s usually under 0.001s of the actual time. It’s no atomic clock, but it’ll do for most of my slow-mo needs. The whole project’s been designed to be as cheap, low-tech, skill-free, and expensive-tool-free as possible.
First up, a little primer – the digits used in the Myst games, aka D’ni digits, are a base-25 numbering system. This means they count up using symbols like , , ,  … , , , . That is, what they call “10”, we call “25” – the same way that in hexadecimal “10” represents what we call “16”. The numbers themselves are based on the numbers 0-4, which are then rotated anticlockwise 90° to represent 5/10/15/20. Here’s an example of D’ni numbers, showing how you add the row & column header symbols together to get the final number symbol:
Each D’ni “day”, or “yahr”, is roughly 30 hours, 14 minutes long and each D’ni “second”, or “prorahn”, is roughly 1.4 seconds. The Guild of Archivists has more details on how the actual D’ni timekeeping system works if that interests you. There’s nothing like these digits anywhere out there on the market, aside from something crazy like using LCD displays, but that didn’t interest me much and wouldn’t meet the goals of cheap or low-tech. So I had to come up with my own… And here’s how that turned out!
There’s so many places I could start with describing how this project was made so I’m gonna pick the one that probably interests most people reading this – the custom D’ni digit 25-segment displays! These are basically like my own custom 7-segment displays, but they’re easier to read with much higher contrast than store-bought 7-segs. I couldn’t find any instructions or guides out there on how to make your own (I’m sure there has to be some out there somewhere), so I had to work it all out myself from trial and error. The design itself was all made in Inkscape. Laser cutting holes in sheet acrylic and filling them with translucent resin was the way to go. The trickiest part is to have even light diffusion throughout an entire cell. The black parts are made from laser-cut 4.5mm black acrylic.
To help bounce light around inside each cell as much as possible, I airbrushed them with a thin white paint before filling them with resin. For the side that was to be the “front”, aka the good-quality side, I wanted the poured resin cells to be smooth & flush with the surface of the acrylic, which is tricky. I placed a piece of clear packing tape on a table with the sticky side up, stretched it out as far as I could, then carefully placed the front of the acrylic piece on the stretched tape. This kept the packing tape under constant tension, so that the resin cured against a smooth flat surface. The empty cells were filled with a 7:1 mixture of clear resin with super fine plaster of paris (mixed before pouring, obviously), which was the best-looking diffusing medium I tried. If you try this, sift the plaster into the resin while stirring to make it as evenly distributed as possible and to reduce plaster clumps in the resin. Use a needle to break up the remaining clumps and to remove any air bubbles that might be stuck in the corners. I recommend carefully picking up the cured acrylic blocks and looking at them from underneath to check for any plaster clumps or bubbles too. A vacuum chamber would be great if you’ve got one to remove the bubbles, but I didn’t have one. Once the resin was cured I carefully removed the packing tape and the segments were ready.
At 4.5mm thick, a single layer of diffusion from this material is likely good enough for most people, but just to make the light segments look extra smooth I used two layers of resin-filled acrylic. However, in this video you can see that there’s a lot of light bleeding from one cell to another, so to seal the edges well, I laser-cut some cardboard gaskets out of 2mm thick black cardboard backing board. I painted the interior edges with a silver pen to increase reflection. I used these gaskets between the two layers of acrylic as well as between the acrylic and the circuit board. I tried adding layers of proper light diffusion film between the gaskets, but they did so little and they would’ve been so fiddly to place in each cell that I didn’t bother.
The custom circuit boards were all made in EasyEDA, which is simple enough to use that it runs in your web browser. The layout was imported from Inkscape’s SVG and I used that to properly position the LEDs. Each board has 50 individual LEDS in strings ranging from 1 LED to 4 LEDs long. There’s 36 discrete cells, or resin-filled holes in the acrylic, but some are always lit up together so there’s only 26 controllable segments. There were 2 different voltages used for these boards – 9 Volts for the strings of 4 & 3 LEDs, and 5 Volts for the strings of 2 & 1 LEDs.
I know a lot of people like to rag on the autorouter feature of EDA software, but for something like this it works perfectly. Aside from a few starting obvious straight traces I put down myself, and a few extra links added right at the end to reduce the chances of the top or bottom planes acting like antennae, everything else was autorouted.
With so many tiny SMD LEDs needing soldering, I definitely recommend paying extra to order a solder stencil along with your circuit board. I have pretty shaky hands due to some medication I’m currently on, but I could manage placing them on the small pads of solder paste left by the stencils. It’s called solder paste but it’s easier to work with (and more accurate) if you think of it as a bunch of tiny beads in oil, rather than an actual paste. If you’ve ever wondered what solder paste looks like up close, here’s some microscope photos!
You can use a fancy reflow oven or an electronics hot plate to fuse the solder, but you can also just use a frying pan on a stove, so long as your pan is actually properly flat. Getting the right temperature is important so check with your brand of solder paste – I used Maker Paste which needs 140’C/284’F. Note that standard cheap IR spot thermometers won’t normally work on metal pans (the pan will reflect the IR light giving a wrong reading), but thermal cameras or cooking thermometers work. One clever hack is to add a few drops of water to the pan & count how long it takes for those drops to boil, add half of that time again, and you should be at around 140’C. Preheat the frying pan and the moment the paste all melts & goes shiny, remove the board from heat – this should take under 10 seconds.
Pro tip – you can use baking paper to help make it easier to pick up when you’re done, but make sure you use paper that’s rated for whatever temperature you’re using. This is what happens when you use cheap paper that’s not rated that high. Oops. Made a super pretty pattern, though.
And here’s what they look like with the solder paste melted solid. Note that you don’t have to actually get the LEDs perfectly lined up when you’re using solder paste to do SMD soldering, if you’re slightly off then surface tension will (hopefully) pull them all into near perfect alignment.
I tried 0804 LEDs but they were too big to fit within the segments so I dropped down to 0603, which if you don’t know what that means, they’re 0.06 inches by 0.03 inches, or around 1.5mm by 0.76mm. This is 100% tweezer territory. Here’s a size comparison for you.
Here’s what the circuit board looks like all lit up
Here’s what the final thing looks like with only one layer of diffuser over the top! It honestly could’ve been fine like this, but because I went the extra mile and made 2 diffuser layers, those segments are more evenly lit than the standard 7-segments I used for the normal digits!
Just because, this is what the digit circuit boards look like with a thermal camera, which is a great way to make sure that all the connections are good. This step certainly isn’t necessary, but I have access to a thermal camera with work, so I figured why not use it.
Put this all together, and you get a finished 25-segment display module for showing D’ni digits! The screws are carefully positioned so the threads will go through the case but the head of the screws overlap the modules to hold them in place. Here’s what they look like – layered like an onion, or maybe an Ogre.
Here’s what the insides look like without any wires connected. Bottom left in pink are some TLC5947 constant-current variable brightness LED drivers, and they’re sitting in standard off-the-shelf breakout boards with heatsinks attachedto them. These are what turn on/off all the LEDs behind the D’ni digits. Bottom right is some power supplies to convert the 9V in to the 5V some chips require (this takes some of the heat load off the TLC5947’s for the segments with only 1 or 2 LEDs in them).
Top middle is another custom circuit board with high-current shift registers to display the “normal” digits. This whole board was designed to be through-hole, as an “easy” design for a beginner solderer to start with. The reason why I’m using a bank of shift registers to control all the LEDs instead of just alternating between them in banks is that this means the display has no flicker and still works during high-speed/slow-motion photography experiments – which is part of what makes it a chronometer and not just yet another fancy clock. Rounding it off is the guts, a branded (not Chinese knock-off; they often have bad power regulators) WeMos/Lolin D1 Mini ESP8266. Having 802.11n-speed WiFi capabilities means it’s already equipped with a reasonably accurate Quartz crystal, to the point that I found an external timekeeping regulator like a temperature/oven based crystal to be unnecessary. The logic it runs isn’t too complicated – connect to the nearest available WiFi point, perform a geoIP lookup, perform a timezone lookup for that location, then poll a few of the nearest NTP servers every few hours. The initial sync is pretty much always within 3ms, and by keeping track of the ESP8266’s clock drift as well as the latency/jitter to the nearest NTP servers (plus a few additional tricks like time of day to estimate the crystal’s temperature variance and waiting for a quiet moment on the WiFi network before transmitting to reduce jitter), its accuracy is refined with each update. Internally it calculates its accuracy in picoseconds (that’s the unit prefix smaller than nanoseconds), but that’s mostly because I’ve been stung enough times by weird edge cases that I try to avoid floating-point maths wherever possible. Officially I’m only calling it accurate to within a best-case of 1ms because that’s a nice round number & is already beyond my home DIY abilities to measure or improve, and just to make extra sure I’m not “overselling” its accuracy that’s why the display only shows a 100ms & a 10ms digit, but not a 1ms digit. One hidden feature of this chronometer is because of the choice of drivers used for the LEDs, I can fully control their brightness and not just turn them on or off – for instance, at night the display dims and the squares around the D’ni digits turn off so it isn’t blindingly bright if you have to go to the bathroom at 2am.
These circuit boards are held up by custom 3D printed standoffs – sure, I could’ve just bought some, but 3D printing some was cheaper.
This design was very cheap and very modular, but its one problem was a ridiculous number of wires were involved – over 450 (!) connection points, all of which have to be connected to wires long enough that you’ve still got enough space to access them, which occasionally gives signal integrity flickers. If I was doing this again, I absolutely would design the digit circuit boards to at least have the shift registers included on them, to drastically reduce the number of potential failure points.
The final step was to laser cut a box to fit this all within. I used the fantastic online tool Boxes.py to make this happen – this is the “Display Case” option. All I had to do here was place holes for the displays & power cable, then get laser cutting. I recommend doing a small test first to make sure you get the play or burn correction settings right depending on how snug a fit you want. This also shows what the box actually looks like, since it’s so hard to photograph glossy black acrylic.
Oh and before I forget – don’t ever give up on your electronics projects just because they seem too hard. I started trying to build this clock nineteen years ago by trying to assemble it out of individual transistors, because modern cheap easy-to-use microcontrollers like Arduinos weren’t a thing, and higher-speed wireless-enabled ones like the ESP8266 were even further away. Building things with electronics is literally getting both easier and cheaper every single year. So if you think something is “too hard” right now, wait a few years and you’d be surprised what other options might be available for you! Here’s one of my failed attempts to build this project from back in 2002 (yes really that old!).
Finally, here’s the SVG of the D’ni Digits including segment numbers, and Gerber files of both the SMD 25-Segment D’ni Display Digit circuit boards and the through-hole normal digit shift register circuit board. You’re free to create whatever you want with these – just credit & link back to me plus let me know so I can see what cool stuff you make! I officially unveiled & presented this chronometer at Mysterium 2019, the annual fan convention for Myst fans. My slides are here, and you can watch my presentation below – I skip over some of the more technical areas but I go more into actual D’ni timekeeping than I do on here.
One final final thing – just to show that the 10ms digit really works and isn’t just a random blur, here’s a slow-mo recording of it at 240fps.
(Before anyone tries to correct me – yes I know there are technically 26 controllable segments and 36 discrete light cells in these displays, which is not 25. But I asked myself “what will people type in their search engines to find this project?”, and since D’ni numbers are base-25, that’s why I’ve decided to call them 25-segment displays instead. So there. 😉 )
I needed some new art for one of my walls and I thought that this time I’d try making something myself. So I came up with this – an array of 21 Silicon Wafers of various types, styles and sizes. The front and back pieces are made from laser-cut acrylic, and the wafers are held in place with 3D-printed/laser-cut clips based on the Chevrons around the Stargate.
The selection of wafers is as varied as I could make it, made by multiple manufacturers across both Europe & America, from 76mm/3 inches to 150mm/6 inches in diameter, from the late 1970s though to the 2000s. Examples include an 8051-compatible microcontroller, a monitor driver chip, military/industrial grade ruggedised memory, a thermometer (DS1775), a Lexmark printer cartridge lockout chip, an Operational Amplifier (DS4812), a MIPS R3010 floating-point co-processor similar to that used in the PlayStation 1 and the SGI workstations used to render 90s things like Jurassic Park and my favourite game Riven: The Sequel to Myst, Solar Photovoltaic panels, interposers, test patterns, bare unpolished Silicon, and even a thin layer of pure 24k gold.
Because the etchings on the wafers are so small, a lot of them produce fantastically vibrant rainbow patterns when the light catches them at the right angle.
Some background if you don’t know what these are: computer chips are created by first growing giant cylindrical crystals of almost-pure Silicon. These are then sliced up into thin wafers and these wafers are chemically etched with all the wires & transistors using mask & a UV light source. Think of it like creating an image on photography paper using shadow puppets & a flashlight. Each wafer normally has hundreds of individual chips, or dies, etched into it. Then they’re cut up, tested, and packaged into their final form. Companies don’t normally sell the raw whole wafers but you can often buy them on eBay, mostly for older wafers and/or manufacturing runs that had defects and were destined for the bin. Prices for etched Silicon wafers vary anywhere between a few dollars to a few ten thousand dollars per wafer, depending on what it is. In total, the whole artwork is made up of many thousands of dies, far too many for me to try and count.
The first step in producing this wall artwork was to create a smaller test version, to see if the whole concept would work & how it’d look, and to iron out any kinks in the process. The prototype I created was made with just one wafer. This wafer was held in place by just the raw screw threads, which didn’t really do a good job to hold it securely in place. Valuable experience gained – come up with a better mounting system for the large design. I used a laser cutter at a lower power level to engrave-remove a few millimetres of acrylic to countersink the screw heads so they didn’t stick out. It took some trial & error but eventually I had it dialled in perfectly so the screws were perfectly flush with the acrylic. This test run was to be a present for my mother, so I picked a wafer that was made the year I was born and shines mostly pinkish (her favourite colour). The actual chips are 256K SRAM memory, so the back’s got a cheesy engraving text about “memories” on it.
Despite some of the wafers being supposedly the same size, I noticed that a lot varied in size a little bit. To account for this, and to hold them in place so they wouldn’t rattle or rotate, each wafer was individually measured and individual mounting spacers were laser cut out of 2mm thick black backing cardboard. Since the wafers are round, I modelled the top holding clips to look like the Chevrons that surround the Stargate. These Chevron clips were 3D-printed on a resin printer – resin printers might be normally slow but when you can print 18 clips at a time, they’re not only quicker than an FDM 3D printer, the end quality is far better too.
The whole display piece was far too large (730mm high * 830mm wide) to be cut in one go on my local Brisbane Hackerpsace (HSBNE)’s laser cutter, so the piece was broken into 4 smaller pieces and glued together. A brutalist aesthetic was adopted for both the jigsaw-like interlocking lines as well as the whole shape. This worked well to hide some of the size limitations so I could get the maximum usable area possible out of the raw sheets of acrylic. For instance, the notch cut out on the middle left isn’t just there for aesthetics, it gives me a couple more centimetres of length for both the upper left and the bottom pieces. Without that notch, neither piece would fit within standard 300mm * 600mm sheets of Acrylic. A top layer of clear acrylic was added to both keep dust away and to protect the wafers. Some of these wafers are so delicate even a single gentle wipe with a fresh microfibre cloth will instantly destroy them (which I accidentally did trying to clean fingerprints off one, oops). It took around 9 months to build, most of which was taken up with trying to acquire as wide a variety of wafers as I could.
When doing any project involving lots of something, it’s important to remember that the time required can quickly balloon if you have to do that job many times over. For instance, there’s 63 3D-printed Chevron clips in this project – spending 8 minutes per object cleaning them up means over 8 hours just cleaning. I tried to keep the part count to a minimum, but even still there’s 21 wafers held in place by 63 3D-printed clips and 63 laser-cut mounting spacers, held together with 63 bolts plus 63 nuts and 63 black end caps, mounted on 4 sheets of black acrylic with 4 sheets of protective clear acrylic over the top, separated by 16 bolts with 48 nuts and 16 end caps… Phew. This all means the total part count for this project was 424 pieces. If I could do it again I would consider removing the laser-cut spacers and merging them with the 3D-printed Chevron clips to reduce the number of parts a little & eliminate one of the construction materials.
Finally, since I know some people love them, here’s some photos of the Silicon Wafers taken with a 500x digital microscope so you can see what they look like up close. The patterns vary widely depending on the wafer – memory tends to look like repeating structures, logic gates tend to look like a random mess, and sensors/anything analogue/test patterns tend to look like some abstract painting. I could swear that one of them has Silicon art of an OR-gate with one leg shorter to make it look more like the Star Trek logo, but it’s just slightly beyond the magnification limits of my microscope so I can’t photograph it. Most of these are from the wafers you see in this artwork, but there’s a few from other wafers I didn’t use.