components. The main part of the circuit is a PIR sensor module that is available readymade in the market. The circuit is also using two transistors and a UM66 melody generator IC.
Working of the circuit is simple; the PIR sensor module detects the changes in the body heat generated through the movement of the body and whenever this change is detected by the sensor its output goes high and switches ON the 2N4401 transistor due to which the melody IC become activated and starts generating the melody. The output of the IC is fed in the BC547 transistor through a 1K resistor to amplify the output of the UM66 to drive an 8 ohms speaker.
This motion sensing melody alarm circuit can be used for variety of security and indication purposes. For example it can be used to detect the entry of a person in the prohibited area. It can also be used for many other security purposes. The circuit is simple to build and using very few
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