Misc Hacks

4137 Articles

Flipping A Coin 10,000 Times With A Dedicated Machine

July 21, 2020 by 32 Comments

Flipping a coin is often the initial example used to help teach probability and statistics to maths students. Often, there is talk of how, given a fair coin, the probability of landing heads or tails should approach 0.5. Of course, if you want to test this, it pays to have a machine do the hard work for you. [Andrew Consroe] has the rig to do just that.

The build consists largely of 3D printed parts. A large cylindrical shroud is used to keep the coin within the flipping area. A spring-loaded dowel is actuated by a stepper motor spinning a cam, which flips the coin. Once the coin has landed, it is photographed with a webcam. An image processing pipeline then determines whether the coin landed heads or tails. A black spot is used on one side of the coin to aid analysis, as the poor-quality webcam images weren’t good enough to recognise the coin in its standard form. Once the flip has been analysed, a sliding aperture is used to push the coin back towards the flipper for the next cycle.

The machine completes a flip approximately every two seconds, meaning 10,000 flips would take approximately 2.5 days. Unfortunately, due to noise and occasional coin escapes, [Andrew] hasn’t yet been able to achieve his goal. He aims to increase speed significantly before making an all-out attempt.

Coin flips can make for decent random numbers, but if you need better ones, perhaps NIST can help you out. Video after the break.

Continue reading “Flipping A Coin 10,000 Times With A Dedicated Machine” →

Clacker Hacker: Hot Rod Switch Mods

July 20, 2020 by 18 Comments

Whether you’re a programmer, gamer, writer, or data entry specialist, the keyboard is an extension of your nervous system. It’s not so much a tool as it is a medium for flow — for being in the zone. So I think it’s only natural that you should care deeply about your keyboard — how it looks, how it sounds, and above all, how it feels to finger-punch those helmeted little switches all the live-long day. That’s my excuse, anyway.

It might surprise you that mechanical keyboard switches can be modified in a number of ways. Depending on what you want from your keyboarding experience, you can make switches feel lighter or less scratchy, quiet them down, or tighten up any wobble in the housing. Why would you want to do this? Because customization is fun. Because electromechanical things are awesome, and because it’s fun to take switches apart and put them back together again. Because it’s literally hacking and this is Hackaday.

This is a pair of plates from a macro keeb I’m making that will sit directly in front of my trackball.

I got into switch modding because I wanted to put Cherry clears in my dactyl, but worried that they would take too much force to actuate and wear my fingers out. So I bought some really light (39g) springs and was really looking forward to swapping them into the clears, but they just don’t work. Like, physically. Slider goes down, slider gets stuck. It will come back up, but only if I hit it again and smear my finger to the side a bit at the same time. Those springs must be too weak to return clear sliders.

I took this as a sign that I should suck it up and use browns instead. After all, no one else has to know what my sliders look like. While I was opening switches, I tried out one of these super-light springs in a brown, thinking maybe they wouldn’t have to go to waste. Not only did the lighter spring work in the brown, it felt pretty nice. It’s hard to imagine how a whole keeb would feel based on a single switch, but if you can gather a handful and snap them into a plate to riffle your fingers over them, well, it’s probably close enough to a full keyboard to get a good feel for whatever mod you’re doing.

Continue reading “Clacker Hacker: Hot Rod Switch Mods” →

A Tin Can Modem, Just For Fun

July 18, 2020 by 9 Comments

Anyone old enough to fondly recall the “bleep-burp-rattle” sequence of sounds of a modem negotiating a connection over a phone line probably also remembers the simple “tin-can telephone” experiment, where a taut string transmits sound vibrations from the bottom of one tin can to another.  This tin can modem experiment puts both of those experiences together in a single project.

As [Mike Kohn] notes, this project was harder than it would seem that it should be. He actually had a much harder time getting the tin can phone part of the project optimized than getting the electronics sorted out, resulting in multiple tries with everything from the canonical tin cans to paper coffee cups before eventually settling on a pair of cardboard nut cans, the kinds with the metal bottoms. Linked together with a length of kite string — dental floss didn’t work — [Mike] added a transmitter on one end and a receiver on the other.

The transmitter used an ATtiny 2313 and everyone’s favorite audio amplifier, the LM386, while the receiver sported an electret mike preamp board, an LM566 tone decoder, and an MSP430 microcontroller. The modulation scheme was as simple as possible — a 400 Hz tone whose length varies whether it’s a one or a zero, or a stop or start bit. Connected to a pair of terminal programs, [Mike] was able to send his name over the wire string at what he calculates to be six or seven baud.

This project has all the hallmarks of lockdown boredom, but we don’t care because it’s good fun and a great learning opportunity, particularly for the young ones. There’s plenty of room for optimization, too — maybe it could even get fast enough for the Hackaday Retro 300-baud challenge.

Continue reading “A Tin Can Modem, Just For Fun” →

Techniques For Making Complex Carbon Fibre Tube Parts

July 18, 2020 by 19 Comments

Many a hacker spent their high school years picking up a few new skills in workshop classes. Whether it be woodworking, welding, or the patient, delicate skill of technical drawing, they’ve been a mainstay of secondary education for decades. However, composites are new enough that they aren’t a major feature of the curriculum. For those wishing to fill in a few gaps, [Easy Composites] have some great videos on carbon fibre techniques.

The video in question concerns the manufacture of a complex cross-section tube part, but these techniques can also apply to more complex hollow sections, like a bike frame, for example. Starting with a mold, the first step is to cut a rough template. This is then used to lay down the first layer of pre-preg carbon fibre material, and a more accurate template is made. The rest of the steps involve the production of a secure lap joint between subsequent layers, and how to properly use vacuum bag techniques on hollow parts.

It’s a useful primer on the basics of producing hollow carbon fibre parts with prepreg material. We’ve featured composites before, with this bulletproof armor a particularly good example. Video after the break.

Continue reading “Techniques For Making Complex Carbon Fibre Tube Parts” →

USB Flash Drive Reveals Strange SD Card Heart

July 17, 2020 by 41 Comments

Many a hacker has dug an old flash drive out of the bottom of a backpack, and peeled apart the damaged plastic case to look inside. More often then not, you’d expect to see some SMD chips on a PCB along with a few passives, an LED and a USB port. [Gough] found something else entirely, and documented it for the interested public.

Inside the Comsol 8GB USB stick, [Gough] found an entire microSD card. One might be led to think this is a card reader and microSD masquerading as a normal flash drive, but the reality is far different. Instead, the drive contains a Flash memory controller which addresses the microSD card as raw NAND, through test points normally covered up on consumer-grade cards. The drive appears to be manufactured from factory second microSD cards that don’t pass the normal tests to be onsold to the public.

Armed with software obtained through spurious channels, [Gough] is able to dive deeper into the guts of the flash drive. The engineering tools allow the card to be optimised for capacity or speed, and different levels of error correction. It’s even possible to have the flash drive emulate a U3 CD ROM drive for OS installs and other purposes.

It’s a great dive into how USB drives work on a low level, and how the firmware and hardware work together. We’ve seen other flash drive hacks before too – like this simple recovery trick!

A Shrine For All The 555 Lovers

July 15, 2020 by 26 Comments

For many of our readers, the classic 555 timer holds a special place in their heart, and cursed be the fool who dares to use an Arduino in its place. For the seriously devoted ones, or those who simply like a novelty decorative item, [acerlaguinto7] built just the right thing: a giant, actually functional, cardboard 555 timer IC.

Taking all the measurements of the original IC, [acerlaguinto7] scaled it up by factor 22 and started cutting out pieces of cardboard — also considering the orientation notch — and added the markings to emulate TI’s NE555P. Next he took a bunch of aluminum cans apart and shaped them into the pins, again staying as close as possible to the original. To top it all off, he put an actual NE555 inside the giant counterpart, and hooked it up to the soda can pins, turning it into a fully operational, oversized timer IC.

Obviously, giant conductive pins like that scream for some dead bug blinky light that even the shakiest of hands could manage to solder, and [acerlaguinto7] certainly delivers, as you can see in the video after the break. One nifty way we could see this taken further would be integrating this breadboard implementation as replacement for the 555 inside — or then just connect it to the giant Raspberry Pi.

Continue reading “A Shrine For All The 555 Lovers” →