Introduction: Laser Beam Sensor Security Alarm
Maybe we've seen the movie scene, when a thief walks down the hall, when he steps past a laser and instantly the alarm goes off. We think it's very sophisticated, but you know it's really easy to make, how to make it, follow the steps below.
Step 1: Make Receiver Circuit
First step we make receiver beam Laser sensor. Transistor BC 547 have a 3 pin, you need connect the pin 2 and pin 3 with LDR modul. Pin 1 Transistor connect to the (-) pin LED, instaling resistor pin 1 connect to the vcc LED, and another pin to pin 2 transistor, look at the picture (1) for more clearly.
Buzzer is attached to both LED pins, adjust the location of Vcc pin and Gnd pin, n the Vcc Pin LED soldering the red wire connected to the On/Off Switch button, and black wire soldering to the pin 3 transistor.
Instal the Charging module look at the module data sheet how to connect the module to a output power and battery.
Re-check all connections and try turning on, if the switch is pressed in the lit state then the led will light up and the buzzer will sound, because there is no laser beam that shoots into the LDR, if it works well, then we will make a case, you can use any used box that is the right size, but here I will make it from cardboard, maybe I no need to explain in detail to make a cardboard case because it's quite easy to make and can be understood by looking at the pictures from this step, you need cardboar, cutter tools and hot glue gun.
Step 2: Make a Laser Beam
For beam laser, i use a cheap laser pointer, to be able to use longer for the laser to beam, so we need changethe battery with rechargable battery, for doing that, open the battery cap, and take out all battery, inside the bady tube pointer there are spring conector we need to make a wire extention so take the black wire and soldering to the spring conector inside pointer, that's a GND wire pin, the Vcc of the pointer is located in the body tube itself, so we only need to solder the red wire to the inside of the pointer body.
Now we have a wire input from laser pointer, install the on/off switch to the red wire, then connect to the Charger module and battery, the the method is the same as installing the charger module in the previous sensor. don't forger using tape press the ordinary button on laser pointer and hold with installing tape around, so the swith change to the On/Off swith button that we installed before.
Re-check all connections and try turning on, when you press the button to on position the laser will light up. for a case same with previous step, you can use any used box that is the right size, but I will make it from cardboard, maybe I no need to explain in detail to make a cardboard case because it's quite easy to make and can be understood by looking at the pictures from this step, you need cardboar, cutter tools and hot glue gun.
Step 3: Testing and Finish
You has made the laser beam sensor for activated alarm this is very easy to build with little cost. So to use this Laser beam alarm, you need to keep these two tools facing each other, for distance, is can be a very long distance, all you need to do is shoot a laser beam at the receiving sensor or LDR module, if the laser beam is blocked then the LDR will not be exposed to the laser beam which will result in activation alarm. Don't forget to charging if the battery out of power.
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