Motion Activated Alarm for your Bag

Many of us carry around a bag with our expensive personal belongings. It can be a pain to carry a bag around with you all day though. If you want to set it down for a while, you often have to try to keep an eye on it to ensure that no one steals it. [Micamelnyk] decided to build a solution to this problem in the form of a motion sensing alarm.

The device is built around a Trinket Pro. The Trinket Pro is a sort of break out board for the ATMega328. It’s compatible with the Arduino IDE and also contains a USB port for easy programming. The Trinket is hooked up to a GY-521 accelerometer, which allows it to detect motion. When the Trinket senses that the device has been moved, it emits a loud high-pitched whine from a piezo speaker.

To arm the device, the user first holds the power button for 3 seconds. Then the user has ten seconds to enter their secret code. This ensures that the device is never armed accidentally and that the user always remembers the code before arming the device. The code is entered via four push buttons mounted to a PCB. The code and code length can both be easily modified in the Trinket software.

Once the code is entered, the status LED will turn solid. This indicates to the user that the device must be placed stationary. The LED will turn off after 20 seconds, indicating that the alarm is now armed. If the bag is moved for more than five seconds at a time, the alarm will sound. The slight delay gives the user just enough time to disarm the alarm. This parameter can also be easily configured via software.

Adding WiFi and SMS to an Alarm System

[Don] wanted to bring his alarm system into the modern age. He figured that making it more connected would do the trick. Specifically, he wanted his alarm system to send him an SMS message whenever the alarm was tripped.

[Don] first had to figure out a way to trigger an event when the alarm sounds. He found a screw terminal that lead to the siren. When the alarm is tripped, this screw terminal outputs 12V to enable the siren. This would be a good place to monitor for an alarm trip.

[Don] is using an Arduino nano to monitor the alarm signal. This meant that the 12V signal needed to be stepped down. He ran it through a resistor and a Zener diode to lower the voltage to something the Arduino can handle. Once the Arduino detects a signal, it uses an ESP8266 WiFi module to send an email. The address [Don] used is the email-to-SMS address which results in a text message hitting his phone over the cell network.

The Arduino also needed power. [Don] found a screw terminal on the alarm system circuit board that provided a regulated 12V output. He ran this to another power regulator board to lower the voltage to a steady 5V. This provides just the amount of juice the Arduino needs to run, and it doesn’t rely on batteries. [Don] provides a good explanation of the system in the video below. Continue reading “Adding WiFi and SMS to an Alarm System”

Arduino-Powered Alarm System Has All The Bells And Whistles

Put aside all of the projects that use an Arduino to blink a few LEDs or drive one servo motor. [IngGaro]’s latest project uses the full range of features available in this versatile microcontroller and has turned an Arduino Mega into a fully-functional home alarm system.

The alarm can read RFID cards for activation and control of the device. It communicates with the front panel via an I2C bus, and it can control the opening and closing of windows or blinds. There is also an integrated GSM antenna for communicating any emergencies over the cell network. The device also keeps track of temperature and humidity.

The entire system can be controlled via a web interface. The Arduino serves a web page that allows the user full control over the alarm. With all of that, it’s hard to think of any more functionality to get out of this tiny microcontroller, unless you wanted to add a frickin’ laser to REALLY trip up the burglars!

5 Digit Security Code Activated Relay Using Mostly Discrete Circuitry

alarm keypad

Let’s rollback the hobby electronics calendar a few decades with [myvideoisonutube’s] alarm activation control circuit using a matrix style phone keypad. The circuit is quite old using CMOS 4081 with 4 ‘AND’ gates to hardwire the access code. [myvideoisonutube] references [Ron’s] “Enhanced 5-Digit Alarm Keypad” schematic for this build changing the recommend keypad with a more common matrix style keypad found in touch pad phones. These types of matrix keypads wouldn’t work outright for the input so he cut some traces and added hookup wires to transform it into a keypad with common terminals and separately connected keys. We love seeing such hacked donor hardware even when it requires extensive modifications. [Ron’s] source circuit included a simple enough to build tactical button keypad if you can’t find a suitable donor phone.

Learning how to use mostly discrete components instead of a microcontroller would be the core objective to build this circuit outside of needing a key-code access point or other secure 12 V relay activated device. Such a device would be quite secure requiring a 4 digit “on” code and 5 digits for “off”. You couldn’t just pull off the keypad and hotwire or short something to gain access either. The 4 digit on “feature” does knock the security down quite a lot. However, all keys not in the access code are connected to the same point so you could increase your security by using a pad with more keys.

On [Ron’s] site you will find a detailed construction guide including top and bottom view for placement of all the components on veroboard. Join us after the break to watch [myvideoisonutube] demo his version.

Continue reading “5 Digit Security Code Activated Relay Using Mostly Discrete Circuitry”

Cloning an infrared disarming remote of a $8 home security system

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[Sylvio] decided to buy one of the cheap alarm systems you can find on the internet to have a look at its insides. The kit he bought was composed of one main motion sensor and two remote controls to arm/disarm it.

Communication between the remotes and the sensor is done by using infrared, requiring a direct line of sight for a signal to be received. Modern alarm systems typically use RF remotes with a typical frequency of 434MHz or 868MHz.  In his write-up, [Sylvio] first tries to replicate the IR signal with one of his ‘learning remote controls’ without success and then proceed to reverse engineering the remote circuit shown in the above picture. Hackaday readers may figure out just by looking at it that it is a simple astable multivibrator (read ‘oscillator’). Its main frequency is 38.5kHz, which is typical for IR applications. Therefore, if one of your neighbours had this ‘security system’ one could just disarm it with any of the same remotes…

[Sylvio] then explains different ways to replicate the simple IR signal, first with an Arduino then with a frequency generator and finally using the USB Infrared Toy from Dangerous Prototypes. We agree with his conclusion: “you get what you pay for”.

Zappo the robot mixes tone generator, sensors, alarm clock and more

zappo-clock-bot

Now [Kevin] claims he built this robot for his 3-year-old son but we know he just used that as an excuse to spend way too much time in his workshop. The robot is a roundup of all the interesting things you can do with hobby electronics. It’s a great example of what you can teach yourself in one year, as [Kevin] only started tinkering with electronics about fourteen months ago.

The robot centers around an Arduino which manages to control a plethora of auxiliary boards. The alarm clock part of the build has a readout in the center of the robot’s chest. There are a bunch of sounds which can be played as the alarm, including a lot of iconic movie sound bytes. Add to that some playful features — like a tone generator which is altered by the column of potentiometers on the left, motion activated eyes, and sound activated ears — and you’ve got a dream-come-true of a toy for your kid.

As a side note, we wrote this several days ago, but ended up bumping it a couple of times in the publishing schedule. We reached out to [Kevin] to let him know a feature was on the way. When he learned that we bumped it in order to feature [Jamie Matzel’s] giant robot he had to laugh. The two met at a mini Maker Faire about a year ago and that interaction is what gave [Kevin] the confidence to start the project.

Continue reading “Zappo the robot mixes tone generator, sensors, alarm clock and more”

Water tank level meter prevents overflow

roof-water-tank-level-meter

Most of the homes in the area where [Raikut] lives have tanks on the roof to hold water. Each is filled from a well using a pump, with gravity serving as a way to pressurize the home’s water supply. The system isn’t automatic and requires the home owner to manually switch the pump on and off. [Raikut] made this process a lot easier by designing an LED bar indicator to monitor the water level.

The sensor is very simple. Each LED is basically its own circuit controlled by a transistor and a few resistors. A 5V signal is fed from 7805 linear regulator into the tank. The base of each transitor is connected to an insulated wire, each extending different depths in the tank. As the water rises it completes the circuit, illuminating the LED.

[Raikut] is conservation minded and built a buzzer circuit which is activated by the LED indicating the highest water level. If someone walks away from the pump switch while it’s filling the alarm will sound as it gets to the top and they can turn it off before it wastes water.

[via Reddit]