A doorbell loud enough to wake the dead

really_loud_doorbell

[Ed Nauman] runs a machine shop, which we imagine can be quite loud at times. Sick of never hearing the doorbell when he was busy working on things, he decided that the solution to his problem was a new doorbell…an incredibly loud doorbell.

His Really Loud Doorbell (RLD for short) is actually a pretty simple device. We imagine he could have wired up an old alarm bell instead, but where’s the fun in that? The doorbell was built using a PIC16F876 uC, which is used to control the air flow through a pneumatic valve. When someone rings his doorbell, the pneumatic actuator pulses up and down, rapidly striking a piece of 1/4” thick steel pipe. As you can see in the video below, it is quite loud and likely to cut through any shop noise without much trouble.

We have seen some extremely loud doorbells before, but we figured that at least a handful of you work in similar environments – have you implemented any inventive ‘notification’ systems in your workspace? Let us know in the comments.

[via Adafruit Blog]

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Detecting muscles with electromyography

The folks at Advancer Technologies just release a muscle sensor board with a great walk through posted on Instructables describing how this board measures the flexing of muscles using electromyography.

Using the same electrode placement points as the remote controlled hand we covered earlier, the muscle is measured by sensing the voltage between the muscle and its tendon. The result is a fairly fine-grained sensing of the output – more than enough to provide some analog control for a project.

The board itself is relatively simple – an INA106 differential amp is used to sense if a muscle is flexing or not. This signal is then amplified and rectified, after which it can be connected to the analog input of your favorite microcontroller. The video demo shows the board connected to a Processing app running from an Arduino, but it wouldn’t be hard to adapt this towards remote Nerf sentry turret controlled by your biceps.

Check out the video after the break to see the muscle sensor board in action.

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Tesla coil bullet-time photography

tesla_coil_bullet_time_photography

One thing we can all probably agree on is that Tesla coils are one part high-voltage electricity and two parts pure awesome. [Rob Flickenger] thinks so too, and he built a pretty nice one in his workshop some time ago. He took a bunch of pictures showing off the coil’s capabilities, but he thought that one photo taken from a single angle didn’t do much to relay just how fantastic it is to watch a Tesla coil in action.

Taking a cue from the Matrix movies, he bought a stack of Canon point and shoot cameras and constructed a bullet time rig in his workshop. In order to get the pictures just right, he flashed each camera with a customized version of the CHDK firmware that allowed him to trigger all ten shutters with a single button press. A few scripts help facilitate collecting all of the images for processing, after which he identifies the good shots and stitches them together. You can see the awesome results in the video below.

[via LaughingSquid]

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Maker Faire KC 2011: In Photos (Part 2)

Be sure to check out Part 1 of the KC Maker Faire photo series. In this post, we explore some of the big hitters of the show, including crowd favorites ArcAttack, as well as battling robots. Read on to see the wonders!

[Read more...]

Tour of Advanced Circuits – A PCB Manufacturer

Although not a hack in itself, many of you may be interested in seeing how a printed circuit board is made in the manufacturing world.  This tour of Advanced Circuits does a good job of explaining the process. The article explains how a PCB will go through a CAD/CAM review, drilling, deburring, and the various chemical etch, plating, and curing processes.

Although many hackers make their own PCBs, having it professionally done can be a good option depending on how many copies are needed. One benefit of this is that PCBs can be checked by an optical inspection process, or even by a “flying lead” machine which works by contacting leads automatically in a computer controlled setup.

A video of this incredible machine is included after the break.  Around 0:26 is when it really starts to get going. [Read more...]

PossessedHand controls hand with electrical stimuli

[Emi Tamaki], [Miyaki Takashi] and [Jun Rekimoto] at the University of Tokyo came up with a device called the PossessedHand that electrically stimulates muscles to train someone to play a the koto, a Japanese stringed instrument.

The PossessedHand ‘triggers’ individual fingers with precisely placed electrodes. Sixteen joints in the hand can be controlled independently by placing one electrode on the muscle that controls the joint and a ground electrode on the tendon of that muscle. Users of the PossessedHand reported no pain from the device when 30 Volts were sent though the electrodes.

The paper (PDF warning) goes into detail about the reactions of the users of the PossessedHand. While a few subjects thought the PossessedHand was scary, many enjoyed it – one subject even thought it was possible to fly a helicopter without training. While this isn’t downloading a rotary wing licence into your brain like The Matrix, the PossessedHand did prove to be a useful tool for learning the fingering for the koto. You can see a video of the PossessedHand in action in the New Scientist story.

[via New Scientist]

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