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Today I will introcude you a hobby motion detection based alarm circuit which you can construct from basic components you can find from market.
This is a simple door alarm which can be found from market (you can use your own alarm circuit)
Our circuit's power voltage is 9 V. This is a 9V battery.
The important part of the circuit is this motion sensor (PIR-555-2807)
This sensor has its own control unit so ready for direct control.
No need for an extra integration effort.
Firstly,
Those kind of sensors does not have enough output current to drive such an alarm circuit.
So we design a simple switch based on BC546 transistor.
Connect a 4.7K-ohm resistor to the transistor base.
Connect transistor emitter to the ground.
Connect transistor collector to the alarm circuit's input voltage pins.
Motion sensor has 3 pins (Ground, Input, Output)
Connect Ground and Input pins to the 9 V battery's -+ pins.
Connect the sensor Output pin to the 4.7 K-ohm resistor which we connected to the transistor's base.
Lets try
Here the only left connection is the sensor's connection. I connect it to activate the system.
Our circuit is active now.
This motion sensor operates up-to 10 meter range.
Let's stop.
Let's move
We stopped moving
Let's move
As you see it immediately detects our motion and the alarm is activated.
In my next study I plan to design a remote control circuit in order to switch on/off the alarm circuit.
Thanks for your time.