hi in this tutorial i am going to show you how i made a ir motion sensor alarm.
this is a simple transistor based circuit here i use two ir led and one ir photo diode.second ir led IS CONNECTED with buzzer parallel through a switch.
this ir led creates a latch because of it our buzzer continuously on even after object is not available.
as i mentioned if we want to stop alarm we need to reset it
with this switch.
here is the circuit diagram for better understanding
now we can test it. you can watch video to understand how it works.