Laser tripwire alarm system uses mirrors to increase coverage

laser_tripwire_alarm

Instructables user [EngineeringShock] has been hard at work building a laser trip wire security system, complete with a combination lock. The security system works just like you see in the movies, employing an array of mirrors to bounce the laser across an opening several times in order to secure the space.

A PIC18F1220 micro controller sits at the center of the alarm and handles the majority of its functions. It takes input from the laser detection circuit, triggers the buzzer, as well as arms and disarms the entire alarm system. An LS7222 digital lock handles the passcode verification side of things, taking input from a 16-button matrix keypad, and telling the PIC when the proper code has been entered.

As you can see in the video below, the alarm system works and the buzzer is quite loud. There is one small problem however – the alarm only arms itself after the proper code has been entered and the lights have been turned off. The light sensing circuit he uses is too sensitive and can only operate in darkness, though he discusses the ability to add a more accurate sensing solution.

If you are interested in reading more about laser tripwire security systems, check out this similar passcode-based system, this alarm system built into a toy, and this Arduino-based alarm system.

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Power-sipping MSP430 mini alarm clock

msp430_alarmclock

[Markus] had a TI MSP430 sitting around from the LaunchPad kit he bought a while back. He didn’t know what to do with it, but eventually decided that it would make a great miniature alarm clock.

He added a shift register to the mix in order to drive his 7-segment LCD display, using two of the MSP430’s output pins in the process. Four more pins were tied to the display’s cathodes, while the remaining two pins are connected to push buttons which register user input.

He crammed the clock’s logic as well as an alarm tune into the chip’s scant 2KB of memory space, literally occupying everything up to the last available byte. The clock is quite a power-miser, using just 2 µA in standby mode. According to [Markus'] calculations, that should enable the clock to use one set of batteries for 10+ years.

While this isn’t the first MSP430 clock we have seen, it certainly is the smallest and most simple.  Stick around to see a quick video of his clock in action.

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Passcode protected laser tripwire alarm system

laser_tripwire

Sometimes security doesn’t need to be overly complex to be effective. Instructables user [1234itouch] recently built a simple laser tripwire alarm that can be mounted virtually anywhere, complete with a keypad for disarming the device.

He mounted a photo cell in a project box, along with an Arduino and a 12-button key pad. A laser pointer is aimed at the photo cell from across a gap, which results in a steady voltage being read by the Arduino. When the laser beam is broken, a drop in voltage is detected, and the alarm sounds until you enter the proper pre-configured passcode. Entering the passcode triggers a 15 second grace period during which the the alarm cannot be tripped again.

It might not be built with triple-thick steel doors and thermo-sensors, but it’s a simple device for simple needs. In its current form it could be pretty useful, and with a little reworking, there are a wide range of things it could be used for.

Continue reading to see a demo video of the tripwire alarm, and be sure to check out these other tripwire-based security systems.

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Edison clock uses Ammeter plus bulbs to set alarm

This is the Edison clock, designed by [David Krawczyk]. It shows time in the same way as the multimeter clock, regulating power to two analog needle meters. The feature that makes this one a bit different is the alarm. You can see the series of holes on the front of the base. These have a small light bulb socked in each, and correspond to hours and 5-minute increments. Insert two bulbs to set the alarm time, and make sure that the alarm knob points to ‘on’. As you can see above, the alarm has been set to 8:15. Hidden on the last image of the article above is a PDF with just a bit more explanation. Still, much has been left out so if you replicate this clock we want to hear about it.

[via Gizmodo and Walyou]

Alarm and wake up light

On the shortest day of the year wouldn’t it be nice to wake up to a bright room? This alarm clock with an integrated wake-up light is one way to do just that. It has some nice features, like a wood veneer that allows the seven-segment display to shine through, but hides it when the display is turned off. There’s also a feature to adjust the color based on ambient room temperature (another way to dwell on how cold it is in your bedroom).

A CC1101 RF chip came to the party, but we can’t figure out what it’s purpose is in this circuit. If you can shed some light on its involvement please do so in the comments.

[Thanks Eric]

Alarm clock learns new trick, opening doors

Waking up at 5:30 in the morning. [Mark Stead] didn’t like the idea either when his chickens started crying to be let out. One simple solution obviously is to eat the chickens build an automatic door opener. The mechanism starts out with an old style mechanical alarm clock, add a geared motor with some creative switch work to pull open the door, weather proof the entire thing, and done. [Mark] even modified the setup later to work with vertical doors. No MCU required for either.

Pair this with an automated feeder system, egg gathering and cooking setup, and you’re half way to having your breakfast ready for you when you wake up in the morning – around noon like the rest of us.

[Thanks MS3FGX]

Burglar alarm in a zippo lighter

surprisingly awesome

[Madmanmoe64] has really done a fantastic job with this burglar alarm built into a zippo.  He crammed a picaxe microcontroller, some IR LEDs, an IR sensor, a battery and various switches in there quite well. It almost closes perfectly, something we think he could remedy if it really bugged him that much.

It has several modes, all initiated by a different sequence of button presses. There is the proximity alarm, which sounds when something moves very close. The reverse proximity alarm which sounds when you remove something from its immediate vicinity.  A doorbell mode, and a silent alarm mode. Check out the video after the break to see it in action.

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