Using Vacuum Tubes As Immersion Heaters

Fellow Hackaday writer [Ethan Zonca] was doing a little bit of woodworking recently and decided to test ammonia fuming on a small piece of oak. Yes, this means discoloring wood with ammonia vapor, and it’s a real technique. [Ethan] wanted to increase the rate of evaporation of his ammonia solution and decided to make an immersion heater. Out of a vacuum tube.

This is a non-optimal solution to the problem of heating a solution of ammonia – already a bad idea unless you have a fume hood – but it gets better. The vacuum tube was slightly cracked, something easily fixed with a bit of silicone sealant. This was then immersed in an ammonia solution, wired up to a driver board and controlled by a homebrew PID controller. If it’s stupid and it works, it’s not stupid.

After getting the ammonia solution up to 30° C, a noxious cloud of ammonia seeped into a piece of oak. This was left overnight, and the result is something that looks like old barn wood, and looks great after some linseed oil is rubbed into it. This is only a test run for fuming an entire desktop this spring, and while that’s a project that will require a real heater (and doing it outside), it’s still a great demonstration of lateral thinking and great woodworking techniques.

Automated Pocky Dispenser

Sometimes, along comes a build project that is not so much a fail, as how not to do it. First off, some of us here had to look up what a Pocky is, never having heard, seen or tasted one – seriously. Once satisfied, we turned our attention to [Michael]’s Automated Pocky Dispenser. Took a while for us to figure out if it’s useful or not. But it’s a fun, quick project that [Michael] put together in around an hour using parts lying around in his office.

For those of you who’d like to know, a Pocky is a chocolate-coated biscuit stick, although you can also buy it in other flavors. You can grab one from a box, but maybe it tastes better when you dispense it by banging a big red button. [Michael] says he used  incredibly advanced construction techniques, but we leave it to our readers to decide on that. The key element of the build is the special “flexible coupling” that he built to transfer the rotation of the stepper motor to the dispensing mechanism. The rest of the build consists of an Arduino, stepper motor, driver, and giant red button. Special motor driving code ensures that the dispenser wiggles back and forth every time, preventing any stuck Pocky’s. And the Electronics are, well, hanging out for all to see. Happy with the success of his build, [Michael] is planning an upgraded version – to connect the Pocky Dispenser to the cloud for statistical gathering of office Pocky habits. He claims even Google does not have that data. To see the dispenser in action, check out the video below.

Continue reading “Automated Pocky Dispenser”

The Best Way to Sport Your Tomatoes

Who eats tomatoes while they run in the first place? No one… and Japanese ketchup company, Kagome would like to change that.

Dole has been sponsoring the Japan Marathon for years, supplying runners with ready to eat bananas to gnosh on-the-go for a quick boost of nutrients. Part of their advertising campaign this year is a Wearable-edible Banana that runners can eat hands free. Out of good humor and a desire to one-up the absurdity level, Kagome worked with known Japanese group, Maywa Denki to create the Tomatan, a smiling contraption that mounts on a runner’s shoulders and delivers tomatoes from a hopper directly into their face… as a reminder that though Japan could be eating wearable bananas, they could just as easily eat mechanically dispensed tomatoes instead.

Why is this awesome? When we’re talking about silliness and commercialism in Japan, the aforementioned Maywa Denki seems to always surface like a nonsense wielding genie. If you haven’t heard the name, this company is actually the identity of an artist group. They have a reputation for inventing mechanical gizmos that are humorously ridiculous, and then marketing them as serious products part of the Maywa Denki brand. The sixteen-pound piggy-back tomato feeder meant to help improve a runner’s stamina is just one example of their many “nonsense machines”.

When we bring the things we create to market, they are usually presented to the world as products of some sort. Maywa Denki bends this common concept of the product to create an identity around their works of art. Because why not solve an imaginary problem that doesn’t really need a solution?

Makes you wonder what kind of obnoxious contraption you’d build to wear in a crowd, huh?:

Dole Japan’s Wearable Banana propaganda:

Powered Double Pendulum is a Chaotic Display

If you’ve never seen a double pendulum before, it’s basically just a pendulum with another pendulum attached to the end. You might not think that’s anything special, but these devices can exhibit extremely chaotic behavior if enough energy is put into the system. The result is often a display that draws attention. [David] wanted to build his own double pendulum display, but he wanted to make it drive itself. The result is a powered double pendulum.

There aren’t many build details here, but the device is simple enough that we can deduce how it works from the demonstration video. It’s broken into two main pieces; the frame and the pendulum. The frame appears to be made mostly from wood. The front plate is made of three layers sandwiched together. A slot is cut out of the middle to allow a rail to slide up and down linearly. The rail is designed in such a way that it fits between the outer layers of the front plate like a track.

The pendulum is attached to the linear rail. The rail moves up and down and puts energy into the pendulum. This causes the pendulum to actually move and generate the chaotic behavior. The rail slides up and down thanks to an electric motor mounted to the base. The mechanics work similar to a piston on a crankshaft. The motor looks as though it is mounted to a wooden bracket that was cut with precision on a laser cutter. The final product works well, though it is a bit noisy. We also wonder if the system would be even more fun to watch if the rotation of the motor had an element of randomness added to it. Or he could always attach a paint sprayer to the end. Continue reading “Powered Double Pendulum is a Chaotic Display”

Toner Transfer And Packing Tape

The toner transfer process of producing PCBs has evolved tremendously over the last few years. It started out by printing PCB layouts onto magazines with a laser printer, then some clever people figured out that glossy inkjet photo paper would work just as well. Now there’s a new substrate for you – packing tape – and it seems to work pretty well.

[David] was designing a cheap board for a robot kit for a workshop and needed 100 tiny PCBs. They were simple boards, and perfectly suited for home PCB manufacturing. He started off by printing directly onto glossy magazine paper, but this wasn’t an ideal solution. During one run, some of the toner landed on the packaging tape he was using to secure the boards. A bit of serendipity came into play and [David] discovered packaging tape is usable in the toner transfer process.

The technique is simple enough: put some packaging tape on a piece of paper, print a board layout (reversed!) on a laser printer, and go through the usual clothes iron/laminator/etching process. [David] is actually using a hair straightener for transferring the toner over to the copper clad board – interesting, and in a pinch you can use the same tool for reflowing SMD components.

Making the Dune “Pain Box” a Reality

If you are unfamiliar with Dune, then you may not know what the pain box is. The pain box is a fictional device that produces an excruciating burning sensation without causing any actual damage. [Bryan] has been working on a project to duplicate this effect in the real world. It sounds like he may be on the right path by using the “thermal grill illusion”.

The thermal grill illusion is a sensory trick originally demonstrated back in 1896. The trick is made up of two interlaced grills. One is cool to the touch, and the other is warm. If the user touches a single grill, they won’t experience any pain because neither temperature is very extreme. However if the user places their hand over the interlaced grills simultaneously they will immediately experience a burning heat. This usually causes the person to pull their hand away immediately. It’s a fun trick and you can sometimes see examples of it at science museums.

The thermal grill illusion sounded like the perfect way to make the pain box a reality. [Bryan] has set specific constraints on this build to make it more true to the Dune series. He wants to ensure the entire package fits into a small box, just big enough to place an adult hand inside. He also wants to keep safety in mind, since it has the potential to actually cause harm if it were to overheat.

[Bryan] has so far tried two methods with varying success. The first attempt involved using several thermoelectric coolers (TECs). [Bryan] had seen PCBs etched a certain way allowing them to radiate heat. We’ve seen this before in 3D printer surfaces. He figured if they could become hot, then why couldn’t they become cold too? His idea was very simple. He etched a PCB that had just two large copper pours. Each one branched out into “fingers” making up the grill.

Each side of the grill ultimately lead to a flat surface to which a TEC was mounted. One side was cold and the other was hot. Heat sinks we attached to the open side of the TECs to help with performance. Unfortunately this design didn’t work. The temperature was not conducted down to the fingers at all. The back side of the PCB did get hot and cold directly under the TECs, but that wouldn’t work for this illusion.

The latest version of the project scraps the PCB idea and uses small diameter copper tubing for the grill. [Bryan] is working with two closed loop water systems. One is for warm water and the other is for cold. He’s using an aquarium pump to circulate the water and the TECs to actually heat or cool the water. The idea is that the water will change the temperature of the copper tubing as it flows through.

While the results so far are better than the previous revision, unfortunately this version is having problems of its own. The hot water eventually gets too hot, and it takes over an hour for it to heat up in the first place. On top of that, the cold water never quite gets cold enough. Despite these problems, [Bryan] is hopefully he can get this concept working. He has several ideas for improvements listed on his blog. Maybe some Hackaday readers can come up with some clever solutions to help this project come to fruition.

Balancing A Ball With A Solar Cell

Go to any control systems class, and you’ll see a final project that demonstrates loops, integration, and everything else that can be learned in a semester or two of control theory. This project is not from one of those classes. It is, however, very cool: it balances a 40mm steel ball on the rim of a lasercut wood wheel using nothing more than a solar cell as a sensor.

[Manuel] was inspired to build this ball-balancing device after seeing a similar project at CCC about six years ago. He doesn’t remember who made it, and eschewed the PC/Matlab architecture of the original, but this build retains one interesting feature of its muse. The input to the control system is just a high intensity light bulb and a solar cell. The 40mm steel ball blocks the light reaching the solar cell most of the time. Slight variations in voltage go through the control system to keep this ball balanced on top of the wheel.

The only hardware for this build is a motor, a motor driver, and an ATMega644P. The first revision of the hardware was just a few breakout boards stuffed into a rat’s nest of wiring in the base of the build, but this has been fixed in version two with a new PCB. Video below.

Continue reading “Balancing A Ball With A Solar Cell”