This TARDIS Is An Infrasonic Subwoofer

April 6, 2016 by 32 Comments

If you’re a fan of action movies or dance music, you’ll probably be familiar with sub-bass. The moment in those James Bond explosions that thuds through your chest in the movie theatre? That’s the product of a large subwoofer, a tuned pipe housing a speaker working somewhere just above the lower limit of human hearing, in the tens of Hz.

[Mike's] TARDIS final build
[Mike’s] TARDIS final build
But what about sound below the range of human hearing, below 20Hz? You can’t directly hear infrasound, but its presence can have a significant effect on the experience of the listener. [Mike Michaud] was interested in this phenomenon for his home movie setup so built himself an infrasonic subwoofer tuned to 17Hz. Since the resulting cabinet was rather large he disguised it as a vintage UK police telephone box that you’d hardly notice in his basement theater. 

A resonant 17Hz speaker horn is a rather inconvenient size for a home theatre, at about 25 feet long. Fortunately there is no need for the horm to be straight, it can be folded into a more convenient enclosure, and that is what [Mike] has done. He used a design published by [lilmike], which folds the horn three times into a more manageable size.

Speaker cabinet construction requires attention to the choice of materials as well as to the driver unit itself, so [Mike] goes into detail on the materials he rejected and his selection of a particular brand of subfloor ply.

He rates the resulting speaker as incredible. His driver is rated for 500 watts but he only has an amplifier capable of serving 100, even with that power he fears for his basement windows. He describes the noise made by the feet of the robots in War Of The Worlds as “little earthquakes” and the general effect as very menacing.

We’ve featured quite a few subwoofers on Hackaday over the years, though with the exception of this rotary device they have mostly been for more conventional sub-bass applications. Here for example is another folded horn. So if sub has become rather run-of-the-mill for you all, how about using it to be entertained by this vortex cannon?

ChaiBot: A Tea Robot Steeped In Utility

April 6, 2016 by 21 Comments

On the surface, a cup of tea is a simple thing to make. Heat up some water, insert tea leaves, and wait for it to steep. The wait time is a matter of taste, and it is absolutely crucial to remove the bag or infuser before it’s too late. Otherwise, you end up with a liquid that’s almost, but not quite, entirely unlike tea.

[Adrian] and his son would often find themselves lost in conversation during the steeping process and let it go too long. But that was before they built ChaiBot, an automatic tea minder. This fine-looking machine uses an old CD drive to raise and lower the tea bags, which are held by a thin piece of stainless steel mesh. Once the bags are lowered, [Adrian] pours hot water into the cups. The weight of the water is detected by a capacitive sensor under the cup cutouts, and this triggers the timer to start counting down to the perfect cuppa.

One of the coolest features of ChaiBot is the built-in circulation. Every minute, the bags are lifted out briefly and reinserted, disturbing the water so the steeping is more uniform. Since the final step to making great tea is drinking it before it goes cold, ChaiBot sends a push notification to [Adrian]’s phone. Be sure to check out the demo after the break.

Here’s another CD drive-based tea bot we covered a while back. It’s not quite as pretty, but it gets the job done. If you’re not one to wander off while your tea steeps but prefer not to watch a clock, here’s a compact timer that’ll fit in your pocket.

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Get Your Game On: Troy’s TVCoG Hosts VR And Gaming Hackathon

April 6, 2016 by 1 Comment

Troy New York’s Tech Valley Center of Gravity is following up their January IoT Hackathon with another installment. The April 16-17 event promises to be a doozy, and anyone close to the area with even a passing interest in gaming and AR/VR should really make an effort to be there.

Not content to just be a caffeine-fueled creative burst, TVCoG is raising the bar in a couple ways. First, they’re teaming up with some corporate sponsors with a strong presence in the VR and AR fields. unspecifiedDaydream.io, a new company based in the same building as the CoG, is contributing a bunch of its Daydream.VR smartphone headsets to hackathon attendees, as well as mentors to get your project up and running. Other sponsors include 1st Playable Productions and Vicarious Visions, game studios both located in the Troy area. And to draw in the hardcore game programmers, a concurrent Ludum Dare game jam will be run by the Tech Valley Game Space, with interaction and collaboration between the AR/VR hackers and the programmers encouraged. Teams will compete for $1000 in prizes and other giveaways.

This sounds like it’s going to be an amazing chance to hack, to collaborate, and to make connections in the growing AR/VR field. And did we mention the food? There was a ton of it last time, so much they were begging us to take it home on Sunday night. Go, hack, create, mingle, and eat. TVCoG knows how to hackathon, and you won’t be disappointed.

Thanks to [Duncan Crary] for the heads up on this.

 

 

Take The Long Road To A Precise Laser PCB Exposer

April 6, 2016 by 23 Comments

According to [diyouware], inside of every HD-DVD player is a gem of laser engineering with the designation of PHR-803T, and it’s just begging to be converted into a PCB exposer. Following along similar hacks which tore the laser diode out of Blu-ray players to expose PCBs, they wanted to use the whole PHR-803T unit without disassembling it, and to try to enable all of its unique features.

They envisioned something simple like a scanner for their machine. Just place the PCB on top of a glass sheet, close the lid, and click print. Unfortunately, moving the laser itself just caused too much vibration. So they switched to an inverted delta robot and named it TwinTeeth. In this design, the laser would stay still and the PCB would move.

What follows next is a seriously impressive journey in reverse engineering and design. The PHR-803T had no data sheet, but a ton of features. For example, it can autofocus, and has three different laser diodes. So many interesting problems were found and solved. For example, the halo from the laser caused the surrounding photoresist to cure. They solved it by adding a glass plate with a UV filtering film on it. Only the most focused point of the laser could punch through.

Another adventure was the autofocus. They wanted to autofocus on all four corners of the board. The PHR-803T was designed to read HD-DVDs so can focus a beam to far below 0.01 mm. They got autofocus working with the UV laser, but couldn’t use it on the PCB without curing the photoresist. So they put a piece of aluminum foil at a known level to start. Then they realized they could use the red or infrared diodes to focus instead. Now they can level the PCB in software, and focus the diode without curing the photoresist.

In the end they have an inverted-delta mini PCB factory. It can produce boards around the size of an Arduino shield with a resolution of 600 DPI. Their machine also has attachments for drilling and solder paste dispensing. Check out the video of it in action.
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Tiny BLE UART Makes Bluetooth Low Energy Simple

April 6, 2016 by 20 Comments

Last time I talked about the internals of how Bluetooth Low Energy (BLE) handles data. I mentioned that the way it is set up is meant to conserve power and also to support common BLE devices like heart rate monitors. On the other hand, I also mentioned that you often didn’t need to deal with that because you’d use an abstraction layer.

This time, I want to show you how I used the Hackaday special edition Tiny BLE (from Seeed Studios) and its mbed library to do a quick simple BLE project. If you didn’t read the first part, don’t worry. The abstraction is so good, you probably won’t have to unless you want to circle back around later and get a more detailed understanding of what’s happening under the covers.

I wanted something simple for an example so you could build on it without having to remove much code. For that reason, I decided to allow my phone to control the state of a three-color LED via BLE. To do that, I’m going to use a virtual UART and some off-the-shelf phone software. The whole thing won’t take much code, but that’s the point: the abstraction makes BLE relatively simple.

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Disposable Camera Flashes Live Again

April 6, 2016 by 26 Comments

Aiming to improve the image quality of the photos on his website, [Jean] needed an external flash unit.

ep-026-0280-960Say what you will about disposable cameras, but the fact that they were mass-produced, and are now nearly obsolete, means they are an absolute treasure trove of electronics components when you can buy them for dirt cheap. So [Jean] decided to turn a few of his disposable cameras into an external flash system for his DSLR (Translated).

He started by taking apart a Kodak digital camera and examining the circuit board. KEY1 enables the charging of the capacitor (the camera ON switch) and SW1 is located under the shutter-release.

Now all he had to do was replace SW1 with an electronic trigger from his DSLR.

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Hyperloops And Robot Cars, A Glimpse Into The Future

April 6, 2016 by 40 Comments

His mobile blooped at him with one of those noises a company spent money to get. A timer started on the screen as he rushed to put his shoes on. He finished and pushed open his door, running down the stairs two to a bound. By the time he reached the bottom of the stairs he had his backpack slung over both shoulders, which he mentally cursed himself for since he’d just have to take the dang thing off again.

It was morning on January first, and he was due at his parent’s house for a new year’s dinner fifteen hundred miles away. He should have booked a plane weeks ago, but now the Loop was his only option. The Loop didn’t really have peak rates, and while the plane would be a little faster, more direct, and cheaper IF he had remembered to book it in time, the Loop would take him the same distance today. Plus, the seats were comfier. They reclined nicely, and he intended to nap on the way. Hopefully, by the time he got there, the bleariness from last night’s celebration would be undetectable by parental senses.

He locked the door to his apartment complex, a reassuringly square assembly from the seventies, and walked to the sidewalk where a friendly light blue car waited for him. When he got close, his mobile vibrated and made another distressingly cheery noise. The doors of the car swung open opposite of each other to expose the space inside. The car displayed two rows of inward facing bench seats, a panoramic row of windows around the entire perimeter of the vehicle, and… yes, his nose was telling him before his eyes fixed on it, a very unsettling amount of vomit in the center of the floor.

He turned around, a bit squeamish, and took out his mobile. He navigated through the controls. Where is the menu option? What year is it now? Why is this still hard? Three awkward menus deep and he finally found and selected the option to let the dispatch know the car had an issue which made it uninhabitable. The car immediately began to chirp warnings and the doors soon started to close. In a moment, a human somewhere in the city would be looking at a video of the inside of the car, determining him a liar or not. As expected, a few seconds later, the little car began to drive off. The lights on the rear of the car turned from bright red to the yellow amber of headlights as it decided its front would be its back. It drove off to the dispatch center for cleaning and repair. Someone would be eating a 100 dollar cleaning bill today. He didn’t feel sorry for them.

His phone began to vibrate. He picked it up to answer a call from a bored customer service representative who was trying hard to sound earnest. “Sorry for the trouble sir, the ride today will be free. We have another car on its way”

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