Year: 2011

More Radiation Test Gear

March 19, 2011 by 19 Comments

This is a multifunction too for measuring radiation (translated). The measurements center around gas discharge tubes that react when ionizing particles pass through them. After reading about the counting circuit for the pair of tubes used in this handheld it’s easy to understand why these are tricky to calibrate. The handheld features a real-time clock as well as a GPS module. This way, it can not only give a readout of the radiation currently measured, but can record how much radiation exposure has accumulated over time (making this a dosimeter). An accompanying dataset records the location of the exposure. An ATmega128 drives the device, which is composed of two separate boards, a series of five navigation buttons, and a salvaged cellphone LCD for the readout. The translated page can be a bit hard to read at times, but there’s plenty of information including an abundance of schematic breakdowns with accompanying explanations of each.

This is certainly feature-rich and we think it goes way beyond the type of device that Seeed is trying to develop.

[Thanks Andrew]

Add A Shutoff Timer To Your Bathroom Fan

March 19, 2011 by 17 Comments

Adding this board (translated) to your bathroom fan will turn it into a smart device. It’s designed to automatically shut off the fan after it’s had some time to clear humidity from the room. It replaces the wall switch which normally controls these fans by converting the fan connection to always be connected to mains.  The board draws constant power to keep the ATtiny13 running via a half-wave rectification circuit. A single LED that rises from the center of the PCB lights up to signal that the fan is in operation, but it is also used as a light sensor, similar to the LED communications hack from a couple of days ago. When the lights go on in the bathroom the microcontroller will turn on the exhaust fan via a Triac. It will remain on until the light level in the bathroom drops.

There’s an interesting timing algorithm that delays the fan startup, and varies the amount of time it will stay on in the dark depending on how long the bathroom lights were on. This way, a longer shower (which will build up more humidity) will cause the fan to remain on for the base of five minutes, plus one minute longer for every two minutes the bathroom was in use. Pretty smart, and quite useful if your bathroom sees high traffic from several family members.

Building A Zoetrope Using Kinect, Processing, And A Laser Cutter

March 19, 2011 by 8 Comments

A zoetrope is a device that contains a disk full with a series of images that make up and animation. A couple of different methods can be used to trick the eye into seeing a single animated image. In the past this was done by placing the images inside of a cylinder with slits at regular distances. When spun quickly, the slits appear to be stationary, with the images creating the animation. But the same effect can be accomplished using a strobe light.

The disk you see above uses the strobe method, but it’s design and construction is what caught our eye. The animated shapes were captured with a Kinect and isolated using Processing. [Greg Borenstein] takes a depth movie recorded while someone danced in front of a Kinect. He ran it through a Processing sketch and was able to isolate a set of slides that where then turned into the objects seen above using a laser cutter.

You can watch a video of this particular zoetrope after the break. But we’ve also embedded the Pixal 3D zoetrope clip which, although unrelated to this hack, is extremely interesting. Don’t have a laser cutter to try this out yourself? You could always build a zoetrope that uses a printed disk.

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512 LED Cube (again)

March 18, 2011 by 37 Comments

We’ve seen LED cubes before, but [nick] upped the ante with his 8x8x8 LED cube that uses only three pins on his microcontroller.

Previous LED cubes we’ve covered drove the LEDs with shift registers and latches, but [nick] used STP16CP LED sink drivers to reduce the component count. The STP16CP can control 16 LEDs each, can be cascaded off of each other, and can operate up to 30Mhz. With a component like this, you’re limited by your microcontroller and not your patience or soldering skills.

While he was waiting for his LEDs to arrive in the mail, [nick] decided he would get a head start on the animation code by plunging into MATLAB. After getting an idea of what would look good on the cube, [nick] wrote the code on his PC to send commands to the arduino controlling the sink drivers. To wrap up the project, [nick] put the cube on a very attractive wooden box stuffed with the electronics. All tolled, a very efficient and elegant build.

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Automatic Dog Dish Filler Never Goes Dry

March 18, 2011 by 37 Comments

automatic_water_dish

[Avatar-X] has a Siberian Husky that gets a lot of exercise throughout the day, and as you would imagine, drinks a ton of water as well. We all suffer from memory lapses at one time or another, and while he is normally good about keeping the bowl filled, he occasionally forgets. He has tried a handful of various auto-filling dog dishes, but none of them seemed to work all that well, and they often rapidly built up healthy bacterial colonies.

With the help of some friends, he rigged up an automatic water dish filler, that ensures his pup always has a sufficient supply of water. He tapped into his kitchen water supply with a standard refrigerator hookup kit, and ran some tubing up into his cabinets, where he placed a garden irrigation valve. The valve is controlled using an Arduino which senses the bowl’s water level using a pair of wires.

The system looks like it works pretty well if the video embedded below is any indicator. [Avatar-X] provides code and schematics for the water control circuit on his site, free to anyone looking to build a similar system for their pets.

If you are interested in learning more about automating some of your pet’s care, be sure to check out these hacks we featured in the past.

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Reviving A Broken HSDPA Modem With A Bit Of Clever Investigation

March 18, 2011 by 17 Comments

hsdpa_modem

Hack-a-Day forum member [Necromant] was recently working on a router when he made a terrible mistake. He connected the wrong power brick to the router, causing a 2.5v over-voltage. The router itself was just fine, as it contained a good stepdown converter, but the HSDPA modem connected to the router’s USB port was not so lucky. It seems that the USB host is powered directly from the router’s power supply without any conversion – this meant his modem got a nice 7.5v zap when he used the wrong plug.

He assumed the modem was dead, so he figured there was no harm in disassembling it. He examined the modem’s circuit board and found that when plugged in, the onboard stepdown converter supplied 0 volts to the rest of the PCB. He couldn’t find any documentation for the converter online, so he employed a little bit of trial and error clever investigation to determine what sort of voltage the stepdown provided before being cooked.

After a bit of testing with his home-built low dropout regulator, he determined that the damaged stepdown provided 3.3v to the rest of the modem (that’s a 4.2v over-voltage for those of you who are keeping track). He added a linear voltage regulator to the board in place of the old stepdown, which worked for about 15 seconds before overheating.

In the end, he decided to add a pretty hefty 3.3v stepdown converter to the modem, throwing aesthetics to the curb. The result is one ugly, but quite functional HSDPA modem.

Speech Recognition Geocache: Se Habla Español

March 18, 2011 by 8 Comments

Instructables user [jorgegunn] has put a unique spin on a recent geocache build by incorporating speech recognition and requiring that the “finder” knows the secret password to access the loot contained within. Although we won’t spoil the fun here, the techie spirit of the build was further bolstered by choosing a password fitting for any trekkie.

Despite utilizing an off-the-shelf speech recognition circuit kit, the majority of this hack was accomplished using parts available at local electronics and hardware stores. [jorgegunn] went to great lengths to make this hack accessible to any amateur hobbyist  and even includes links to relevant tutorials, schematics, and online parts vendors where applicable.

The actual speech recognition is accomplished with an Images Scientific Instruments model SR-06 circuit kit, capable of recognizing up to 40 different predefined words across multiple languages. Any time a correct match occurs, a value corresponding to the memory slot for that word is displayed on a pair of 7-segment displays. A separate decoder circuit based on a 74LS373 D-Type Latch and 4028 IC Decoder CMOS determines if the value being displayed constitutes a valid response and then drives a solenoid via a Darlington transistor in order to release the latching mechanism. Once opened, the device is simply pushed closed again to await its next finder- we are guessing that finding it might actually be the easiest part as judged by its size!

Although the real-world battery life has not yet been determined, a single coin cell for memory retention and a 9V battery used to drive the circuit and for latch release lasted through a full month of testing without any issues. Battery life could be extended almost indefinitely with a simple solar cell and rechargeable battery setup, but this would also obviously increase the likelihood of vandalism and/or theft.

We can imagine many different applications for such a device as-is including automated door lock  mechanisms and even access control to things such as the controls on a computer case.  It should also be fairly easy to increase the security by stringing multiple words together into a password or by instituting a “time out” period after a certain number of incorrect guesses.

Let us know of any other applications or build variations in the comments below and make sure to see how it all came together in the short videos after the break.

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