Project ideas

The iconic "555" timer IC is named after its voltage divider, which uses three 5 kΩ resistors. If those resistors had been slightly larger, the IC might have ended up being called "666". It would not be difficult to build one from parts using 6 kΩ resistors.

With the new net metering rules, feeding electricity back into the grid doesn’t pay off much any more. I might as well do something useful with the energy instead of giving it away. I could mine Bitcoin — free money, and it would generate heat, which is nice in winter. But I have serious ethical concerns about the enormous energy consumption involved in Bitcoin mining, so I’d rather do something more morally justifiable.

Perhaps I could run protein-folding computations instead. That way, I help advance scientific research and still get free heat from my computers. The software would need to scale up and down dynamically depending on how much solar power is available. I could read my electricity meter and adjust the load so that both consumption and feed-in balance out at zero.

After attending a large hacker conference again and seeing the many Datenklos spread across the fields providing network access, I decided I wanted to create a scale model to provide network access on my desk.

There are several mobile toilet toys for children. Maybe I could fit a few small networking switches inside one—or even print a tiny 19" rack for it.

Last night I dreamt of a tiny bread machine, just big enough to make a single kruidnoot (a biscuit roughly the size of a coin), complete with a tiny bag of mix.

Since you're supposed to be able to build nearly anything with a 555 timer, let's find out if I can create a guitar distortion circuit around one.

When I accidentally bricked my EV charger firmware, I realised how complicated — and not at all repair-friendly — the potted board was. It had an invalid value in persistent storage, with no way for me to fix it. But why are these chargers so complicated? Charging an EV is not that difficult. In fact, I think I could do it with a 555.

Thinking it through, I already have all the parts from the bricked charger, and SAE J1772 signalling is really just a square wave, so why not make good on my statement and actually build one? It’s especially amusing to me because the 555 design is over half a century old, yet it can still be used in something as contemporary as an EV charger.

Sometimes nudity is censored with mosaic pixels (because the world would apparently end if we ever saw a female nipple). Those pixel mosaics always remind me a bit of a QR code. So why not replace them with actual QR codes? These could even link to the original image, which obviously defeats the censoring—and is therefore absurd and hilarious (at least in my head).

Having recently acquired a phone capable of inductive charging, along with an inductive charger, I began wondering what more could be possible with this system.

I could design a PCB with an integrated coil, allowing me to power a badge or even a business card. And since there’s communication between the phone and charger, I could turn it into a debugger or perhaps perform a man-in-the-middle attack on the phone or charger—sort of like a Qi Flipper. Since you can manipulate the frequency of a charger, maybe it would be possible to turn it into an AM or FM radio transmitter? Or produce audible sounds?

I once saw a miniature Persian-rug mouse mat. That concept would translate beautifully into a contactless phone charger.

I enjoy colourful event lighting and have often thought about how I could make some myself.

This idea is for a modular system of sticks and corner pieces. The sticks are roughly half a meter long, made of white acrylic, and can light up in any colour. The corner pieces are black. Sticks and corners connect with sturdy connectors that provide both mechanical and electrical connection. You can assemble them in any configuration, creating all sorts of cubes. With a few different stick lengths and flexible corner pieces, many more shapes would be possible. The concept borrows a bit from plumbing, scaffolding, and truss structures. One corner would be used to connect the sculpture to power and a computer.

Every stick and corner piece would contain a microcontroller, connected to its neighbours, forming a mesh network. By querying which module is connected to which, the computer could map the entire sculpture — and use that as part of the lighting effects.

Some electric vehicles have vehicle-to-grid functionality, essentially turning your EV into a mobile power socket. My motorcycle doesn’t have that, so I was wondering if I could make it myself. Being able to plug in your kettle on a picnic sounds tempting, doesn’t it?

What I know about fast-charging EV batteries is that the charger performs a handshake before connecting directly to the battery. So wouldn’t it be possible to send the appropriate signals and have the battery terminals exposed on the charger socket? From there you could connect an inverter and get your mains output. But if it's only for a kettle, you might as well hook it up directly to the 300 Vdc from the battery. I find it funny to be using the charge plug for dis-charging instead.

When you're queuing in front of a traffic light, don't you find it annoying when your turn signal blinks at a slightly different rate from the car in front of you? There’s even an XKCD about this. But fear no more — the turn-signal sync-o-matic is here. Or at least, the idea for one is.

It should be perfectly possible to use a simple, low-resolution camera with a view of the car in front, isolate its turn signal, and adjust the frequency of your own indicator to match.

And for modern cars that already have cameras on board, it could be as simple as a software update.

While thinking about how to tell a school class of children about my Tetris window, I started looking into old Game Boys to use as examples. That set me thinking about link cables and programmable cartridges. Then I wondered: could I make a programmable cartridge myself, with all ROMs stored on a microSD card, like an R4 card?

Could I even include a wireless link cable in the cartridge? With the Game Boy Advance, you could share a cartridge over a link cable if you were playing together. Could the same be done here? And multiplayer for the games that support it? And what about updating your programmable cartridge over WiFi?

More and more things are USB-powered, and USB Power Delivery can supply quite a lot of power these days. Would this be enough to charge my electric motorcycle? There are no USB-PD-powered inverters around yet, but that is probably only a matter of time. It might even be possible to build a fast charger that outputs battery voltage directly.

Would it be possible to remake the iconic children's toy in which the square peg intentionally does not fit in the square hole, but only in the round one? And the other way around? Teaching children (and adults) to think outside the box, instead of obediently following the rules.

After watching old James Bond films, with revolving number plates on his car, I realised that a modern-day Q would simply use e‑paper. Doing so would almost certainly be illegal, I expect, as such plates would be very easy to change indeed. But I couldn’t resist searching the web, and was amazed to discover that not only can you buy e‑paper number plates online, but they’re even street-legal in California!

I’d just used my Makita fast charger for the first time. When it finished, the charger loudly played this incredably annoying tune. So I thought what any hacker would think: could I change the tune? What would it take to make it play Mario?

It turned out there are a few different tunes pre-programmed, but no way to add a custom one. Challenge accepted.

And… someone beat me to it.

Taking a bike on the train costs money, whereas taking a folding bike is free of charge. The only definition of a folding bike used is a bike that can be folded. So I could just cut my bike in half, weld in some hinges, and have a bike that travels for free with me on the train. It also saves the hassle of buying a special bike-ticket. This trick might only work in the Netherlands, though.

In a wave of nostalgia, I wondered what my website would look like in an old browser. I imagined creating a web proxy that scales the display to the resolution used in 1999, fakes a Windows 98 background with a Netscape icon, and generally simulates the 1999 browsing experience. It could slow the connection to modem speed, show a dial-in window, and maybe even play the modem sound.

But it turns out OldWeb already exists.

I had just started watching LEGO Masters, and my head was awash with ideas. At the same time, I was working out increasingly radical Pokerwork—a type of melodeon—mods. Those two streams connected in my mind, and I thought: why not make a melodeon out of LEGO? And by this, I mean a full-size, fully functional musical instrument. There is no playable (or even 1:1 scale) LEGO melodeon anywhere on the internet, so I could be the first!

Nearly every part could be made from LEGO, I expect, with the only exceptions being the reeds that produce the sound and the bellows. I might need to resort to gluing—a faux pas among LEGO purists—to make the instrument airtight and prevent the bricks from pulling apart on the draw.

A funny fact is that LEGO stands for "play well" in Danish. That’s exactly what we’re aiming to do here: play a LEGO squeezebox.

What would a modern-day Ouija board look like? To begin with, I think the letters should be arranged in a QWERTY layout instead of alphabetical order. It should also have USB, and at least one LED. Perhaps it could include some of the symbols commonly found on a modern keyboard, such as emojis — the dead you’re trying to contact will increasingly be using those.

The board could be turned into a keyboard or an absolute pointing device, Wacom-tablet style, using the planchette as a mouse. It might even be possible to drive the planchette itself using magnets.

When I read on The Register that a Harry Potter magic-wand infrared TV remote control had come out, my mind immediately began bubbling with possibilities. I wanted to build one, of course, but there are all sorts of entertaining things you could do with a magic wand. If you included, say, a microcontroller with Bluetooth, you could use it as a remote control for giving presentations.

However, as prototypes are generally a bit bigger than the finished product, it would never fit inside such a slim staff. So what sort of enclosure would have enough space inside for the prototype, and roughly the shape of a magic wand? Then the idea popped into my head that I could use an empty vibrator casing.

I could already picture myself waving the prototype about in front of the TV and having to explain to everyone that it was just the remote control. I found this image hilarious — even more so if the prototype turned out to be tiny and would have fitted into a wand after all.

When you look at it, a DIP IC does resemble a little bug. Why not add some wings and antennae and turn it into a sculpture? It certainly fits the "That could have been done with a 555" meme.

With modern doorbells capable of playing any sound you put on an SD card, wouldn't it be hilarious to record myself saying "ding dong" and use that as the doorbell sound? That would be even more low-tech than using the old-fashioned ringing phone sound on a mobile.

But then I read that composer Philip Glass has a clock that plays samples of someone saying "boing". So much for my original idea.

One day — as these things go — I wondered whether I could make a chandelier out of PCBs. Each arm would be a board, and all the boards would slot together in the middle, much like a cardboard model. There would be LEDs where the bulbs would normally be, and it would be fully functional, of course.

One day, while cycling to work through the meadows, I began to wonder: would it be possible to make a phone charger that is powered from the electric fence? That would be perfect for long cycling trips (this was before power banks became common).

The verdict (it’s quite a trip, so I had plenty of time to think this over) was that, while technically possible, it would not be very practical. Only a very small amount of energy is transferred with each pulse, and at one pulse per second it would take days to charge your phone, rather defeating the purpose. But still, it can be done.

While working in a different office for a few weeks, I had a colleague, Luuk, who was always singing Een vers kopje theeeee (a line from Alles kan een mens gelukkig maken (1989), Het Goede Doel & René Froger) with every cup of tea he made. This gave me the idea for a going-away present: a box that you plug in between the mains socket and the kettle, which would play this sample every time the kettle boils.

Imagine a clock where the hours and minutes are displayed using progress bars. You would be slowly progressing through your day.

Your day is loading:
hours:   |==    | 16
minutes: |===   | 30

Seeing hackers generate composite video and sound from AVRs, I wondered whether it would be possible to generate S/P-DIF audio from one. It should be perfectly doable — in fact, it ought to be easy compared with generating composite video.

At one time, I wanted to have an old rotary phone in the house—not just as decoration, but as something useful. So I figured it could serve as the doorbell. Anyone ringing the front door would produce that lovely old "Rriinnggg" sound.

Ringing a POTS (Plain Old Telephone Service) phone is a bit different from ringing a doorbell, though. Doorbells usually operate on 9Vac at 50Hz, while phones prefer 50Vac at 25Hz. The cheapest PBXs use 50Hz to ring phones, but it doesn’t quite sound the same. It shouldn't be hard to whip up 25Hz on an AVR with a sine table.

I’ve seen very nice phone ringers for sale, aimed at theatre productions, some even with DMX input. But with a price tag of 200+ Euro, I find those far too expensive for my doorbell. But why buy when you can build?

Back in 2001, MP3 was the music format of choice. It worked well on computers, but few affordable portable players existed. I had just picked up a Game Boy — which was very uncool at the time — because I had always wanted one, and they were dirt cheap then (I paid 4 Euro). Turning an uncool Game Boy into a very cool MP3 player sounded like exactly the kind of statement I wanted to make.

By itself, the Game Boy is not fast enough to decode the MP3 format, but it has everything else: buttons, screen, batteries, speaker, and headphone amp. There is even a pin on the cartridge connector wired directly to the audio amplifier, so cartridges can play sounds as well as the Game Boy itself.

Then the VLSI Solution VS1001 came out: a single-chip MP3 decoder and DAC. With one of these, it would be possible to make a Game Boy play MP3s. Simply put the VS1001 in a cartridge along with an SD card for MP3 storage and an EEPROM for the Game Boy software.

My project never saw the light of day, but I later discovered that in that same year the SongPro MP3 cartridge for the Game Boy was released.

I could still be the first to turn a Game Boy into a portable movie player, though.