Wireless door alarms protect your stuff from afar

wireless-shed-alarm

[Webby] had a friend named [Steve], and as the story goes [Steve] had a few storage sheds on his property that were prone to break-ins.

While the doors were all fitted with a lock, wooden doors are only so strong, and are easy fodder for intruders bearing crowbars and the like. [Steve] was looking for a good way to know when people were poking their heads where they don’t belong, so he rigged up a set of simple alarms that let him know when it’s time to break out the shotgun.

On each of the shed doors, he installed a small IR proximity sensor wired up to a PIC12F675 microcontroller. The PIC is is connected to the “call” button a medium range wireless radio, so that whenever the IR sensor detects that the door is ajar, the PIC triggers an alert on the base unit.

The solution is simple, which we figure also makes it pretty reliable – nice job!

Building a battery-powered motion alarm

[Brad] was asked by his Sister to design a motion-based alarm that would help her catch her son sneaking out of the house at night. Obviously this didn’t need to be a long-term installation so he decided to throw something together that is only active at night and can be battery-powered. What he came up with is a light-sensitive motion sensor that uses very little power.

He knew that an Arduino would be overkill, and decided to try his hand at using the Arduino to develop code for an ATtiny85. It has an external interrupt pin connected to the output of the PIR module, which triggers action when motion is detected. The first thing it does is to check the photoresistor via the ADC. If light levels are low enough, the buzzer will be sounded. [Brad] measured the current consumption of his circuit and was not happy to find it draws about 2.5 mA at idle. He spent some time teaching himself about the sleep functions of the AVR chips and was able reduce that to about 500-600 uA when in sleep mode. Now all he has to do is find a nice place behind the house to mount the alarm and there’ll be no more sneaking around at night.

If you’re trying to keep a tight leash on your own kids you could always make them punch the time clock.

Chilean teen builds automatic earthquake alarm

chilean_teen_earthquake_alarm

When an earthquake is about to strike in Chile, who do you think is first to sound the alarm? You might be surprised that it’s not the government, but rather a 14 year old boy.

After living through an earthquake in 2010 and seeing the devastation this spring in Japan, Chilean teenager [Sebastian Alegria] decided that he wanted to construct something similar to Japan’s earthquake warning system. He purchased an off the shelf earthquake detector for less than $100, and connected it to his computer via an Arduino.

Now, whenever seismic activity is detected, his sensor tweets an alert letting his 29,000+ followers know that a perceptible earthquake is 5 to 30 seconds away. Apparently the Chilean government is working on a similar system that is still at least a year away, so in the meantime his fellow citizens rely on [Sebastian] instead.

While it might seem like a relatively easy hack to pull off compared to other earthquake detectors, we’re impressed by [Sebastian’s] creativity, and his will to help others. He’s been pounding away at computers since he was about 4 years old and has several other popular Twitter-based projects under his belt already, so we won’t be surprised if we hear from him again in the future.

Tweeting home alarm system

tweeting_home_alarm_system

Instructables user [willnue] wanted to build a DIY Tweeting alarm system from the ground up, but reconsidered after taking a close look at the scope of such a project. He settled on using an off the shelf security system, taking care of the Twitter interface on his own. He bought a GE 45142 Wireless alarm and promptly disassembled it to see how he might retrieve status messages from the unit.

He figured that monitoring the alarm’s LEDs would make the most sense, so he used a bit of Ethernet cable and wired all of the system’s indicators to his Arduino board. He hooked up an Ethernet shield to the Arduino, then wrapped the pair up in a plastic project box that closely matched the look of the security system. Once that was done, he wrote some simple code for the Arduino that monitors each of the alarm system’s six status lights, sending updates to Twitter via the ThingTweet service.

With this system you might not get your status messages in time to foil whoever is carrying off your plasma TV, but at least you will know what to expect once you get home!

If you want to keep tabs on [Will’s] security system to find out the best time to rob him see how things are going, check out his Twitter feed here.

Automotive backup alarm

[Dino's] project of the week is a backup alarm for your car. This is a feature that has become popular on many large vehicles like SUVs where visibility is an issue when moving in reverse. But it doesn’t sound like he was motivated by the need to have this in his own car. Instead, he was looking for something to build using a laser range finder.

[Joe Grand] (the brains behind DEFCON badges) has been working on an inexpensive laser range finder for Parallax. He sent one of the first-run prototype boards to [Dino] for beta testing and we’re glad that [Dino] decided to show it off. It uses a small red laser diode and a camera module to measure distance in millimeters. The board communicates serially and this particular project uses an Arduino along with a character LCD and speaker to display distance and sound an alarm when the car is within a meter of an object.

Check out the video after the break to see the build in its entirety. The system works reasonably well, if the object you’re about to hit is perfectly lined up with the laser dot.

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Modular security system is portable too

diy_security_system

Hackaday reader [Oneironaut] wrote in to share a modular, portable security system he built for himself.

He likes visiting the Caribbean, but his favorite vacation spot is apparently rife with cat burglars. He enjoys sleeping with the windows open and wanted to find a way to scare off ne’er do wells. At home, there are a few different buildings on the property he owns, and he was looking to keep curious trespassers away.

The alarm system was built using a matrix keypad that interfaces with an ATMega88 micro controller. The micro controller handles all the logic for the system, triggering an attached “pocket alarm” when ever the sensor is tripped. Like most household alarms, it is armed and disarmed via the keypad, giving the user 60 seconds to enter the disarm code if the alarm has been mistakenly tripped. A wide array of trigger methods can be used, from mercury switches to motion detectors, since his alarm uses a simple plug interface that accepts any two-wire sensor.

Now, no one is claiming that this is high security by any means – the alarm addresses a couple of specific scenarios that apply to [Oneironaut], which may also be applicable to others out there. At the end of the day, the alarm is more meant to scare an intruder into fleeing than anything else, and in that respect, it works perfectly.

Continue reading to see a quick video demonstration of his alarm system in action.

[Read more...]

DIY sunrise alarm clock

sunrise_alarm_clock

As a project for an embedded systems class, [Alan] recently built himself a sunrise-simulating alarm clock. You are probably familiar with these sorts of timepieces – they gradually light up the room to awaken the sleeping individual rather than jarring them awake with a buzzer or the radio. Since many commercial units with this feature are sold for $70 and up, his goal was to replicate the functionality at a fraction of the cost, using only open source components.

An Arm Cortex M3 processor runs the show, displaying the time via a pair of 8×8 LED matrix panels on the front of the device. The clock is programmed to gently wake up its user by simulating a sunrise over a period of 5, 15, 30, 45, or 60 minutes. If the user has not woken up before the sunrise simulation is complete, the clock resorts to a traditional piezo alarm to rouse the heavy sleeper.

The project is nicely done, and after looking at his bill of materials it seems to be far cheaper than many sunrise alarm clocks you will find in stores.

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