AVR Guardian Filters Out Dogs

Cats and dogs can get along quite nicely when they are raised up together. The problem with this type of arrangement tends to be keeping dogs out of the cat box and away from the cat food. [Ryan Meuth] tried out a simple electronic barrier to keep the dog away. It uses an IR transmitter and receiver to shine a beam of invisible light across the doorway to his cat room. In the demo after the break you’ll see that he took steps to make sure the cats don’t set off the alarm. The beam of light is set high enough that their bodies don’t get in the way, and the firmware measures the amount of time the beam was broken in order to avoid false positives caused by the cats’ tails. If the dog does try to get into the room it will break the beam and set off a high-pitched alarm sound.

It’s interesting that the dog doesn’t like the sound but the cat’s don’t seem to be scared of it. Also, we’ve got a less-than-ferocious feline that would love to chew on the cord that connects the two modules. Still, it’s a solution that works for [Ryan] and could be incorporated into an automatic feeder to keep the dog away from feedings while you’re out of the house.

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Waking Up With The (fake) Sun

[Bogdan] has some trouble getting up in the morning. A blaring alarm will do the trick but that’s no way to start the day. To get him through the dark winter months he wanted to try a sunrise simulator. He patched into the alarm signal of his bedside clock, intercepting the command from the clock’s microprocessor and using it as an input for his own ATtiny13. From there, the tiny13 gradually brightens a 150W halogen lamp using a triac until his room is as bright as a July morning. A signal is then sent to the alarm clock’s audio amplifier to turn on the audible alarm. He’s got the system set for a 20-minute sunrise so it’s just a matter of programming his alarm 20-minutes early than the ‘I absolutely have to get out of bed now’ time.

Intruder Alarm McDonald’s Toy Hacking

[malikaii] needed to set up some kind of tripwire style alarm system for his office. His bosses kept sneaking in to find him slacking. So, like any loyal hacker, instead of just working harder he built an alarm system. After a failed attempt to recreate an IR alarm circuit he found on the web and built from old appliance parts, he found the Hack a Day article about harvesting McDonald’s toys. The end result was a fully functional IR detecting alarm for the office doorway. This is pretty simple really, the best kind of hack.

PC Fan Failure Alarm

[youtube=http://www.youtube.com/watch?v=Jznl8U9zzKM]

Need to monitor not only if a fan is running, but if it is running fast enough? Check out this PC fan failure alarm circuit. After several failed attempts using various circuits, they settled on a Schmitt trigger. They even show a couple variations including a manual reset and a relay instead of a buzzer.

[via HackedGadgets]

Time Delay Door Alarm

Ever accidentally left your front door ajar and had a pet escape? [BlackCow] came up with a simple solution to this problem. The circuit is fairly rudimentary but a great example of using the basics to get the job done. Now, instead of having an alarm that sounds as soon as the door is open, he has a 30 second delay. This helps avoid the “boy who cried wolf” effect also known as the “vista security warning” effect of being bothered too many times for a non issue.  We also have to say that we like his taste in blog layouts.

[via Hacked Gadgets]

Gentle Wake Up Alarm

[Michiel], unsatisfied by his Phillips wake up light, decided just to make his own. He really wanted programmable weekend alarms as well as an easier to find snooze button. At first, his circuit was not reliable enough, losing several minutes per hour, but he gutted another alarm for the 1Hz crystal. After some carpentry, his final alarm ended up quite nice.  After so many aggressive alarm clocks, it’s nice to see that not everyone needs to be assaulted out of bed.

Correction: apparently, there’s no 1Hz crystal. That was a guess on my part. -[Caleb]

[via Hacked Gadgets]

Clocks That Only A Geek Could Love

Alpha-Geek Clock

Oh this one’s good! This clock has a built-in WWVB receiver to make sure the time is always accurate. But with just one LED as the display we wish you good luck when reading it! A whole bunch of info (time, day, year, etc) is blinked out in binary encoded decimal. [Thanks Tymm]

Standard Time

Manual labor. This clock is an art installation in Rotterdam. In the video you can see that workers changed the segments of a four-digit display every minute over a twenty-four hour period. Since they filmed it we’d expect the ability to turn this into a video clock like the one we saw last week. [Thanks David]

International Clock

Low-tech but highly creative. The instructional video uses basic geometry and the workings from a cheap clock to craft an international clock. There are twelve labels corresponding to different time zones. Put the zone you want up and read the clock as normal. [via Red Ferrett Journal]

Princess and the Pea

There are few who will agree to have an air tank as part of an alarm clock. The Princess and the Pea concept uses compressed air to inflate an exercise ball in between the mattress and the box spring. Watch this video to see how it will roll you out of bed if the hissing air sound didn’t wake you first. At least it’s more gentle than the pneumatic alarm clock from last June. [via Neatorama]