Automotive Backup Alarm

June 26, 2011 by Mike Szczys 11 Comments

[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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An Alarm For Every Day Of The Week

May 19, 2011 by Mike Szczys 27 Comments

If you don’t have a 9-to-5 type of job you might find yourself constantly resetting your alarm clock as your calendar commitments change. [Lucas] finally got fed up with the nightly ritual and decided to build his own alarm clock which has unique settings for each day of the week (translated).

The display itself is an LM044L 20×4 character display. This provides a viewing area that is about 3″x1″ and since it’s an HD44780 compliant LCD screen, writing data to it takes very little effort (and RAM) compared to a graphic LCD. A PIC 18F2550 drives the device, taking input from a half-dozen buttons, driving the display, and turning on the enclosed buzzer when it’s time to get up. There’s a backup battery which will keep the settings when power is lost. The daily alarms, current time, and back light brightness can all be adjusted from the four screens that make up the settings menus. The only thing that it’s missing is a precision timekeeper, but that should be easy to add either by measuring the frequency of the mains or by using an RTC chip.

DIY Sunrise Alarm Clock

May 4, 2011 by Mike Nathan 15 Comments

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.

Laser Tripwire Alarm System Uses Mirrors To Increase Coverage

April 18, 2011 by Mike Nathan 15 Comments

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

April 4, 2011 by Mike Nathan 12 Comments

[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

March 11, 2011 by Mike Nathan 13 Comments

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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IR-controlled Musical Alarm Clock

February 15, 2011 by Mike Nathan 11 Comments

Forum user [Frank] shared with us his recent project, a musical alarm clock. More than just a simple alarm clock, his creation allows the user to load music onto a micro SD card, has alarm settings for each day of the week, and best of all, can be controlled using an IR remote. He uses a Teensy++ to control most of the clock’s functions including the display, delegating the time keeping to a DS1307 real-time clock. All of the audio playback is handled by a separate music decoder mounted on a breakout board.

His Instructables writeup is extremely detailed, with tons of annotations, pictures, diagrams, and source code available. He walks through each step in detail, making this a great learning guide for others looking to start in on AVR programming.

His final presentation is a great lesson in recycling, though unfortunately a bit lackluster, as the clock is packaged in an old SparkFun cardboard box. He does mention that there were some time constraints towards the end, which may explain this choice – it would be nice to see a revised version of this clock packaged in a nice plexi case.