Presented here is a window alarm annunciator based on Arduino Uno board.
Circuit and working
The circuit diagram of the window alarm annunciator is shown in Fig. 2. It is built around Arduino Uno board (board1), seven LEDs (LED1 through LED7), three tactile switches (S1 through S3) and a few discrete components.
This annunciator has seven inputs connected across connectors CON1 through CON7 for initiating the alarm through normally-open (NO) contacts. There are also three input switches (S1 through S3) for test, acknowledge and reset. There are eight outputs, out of which seven are connected with LEDs, corresponding to seven input alarm contacts, while the eighth output is provided for the buzzer. (The buzzer can be replaced with a hooter using additional circuitry.)
All alarm inputs are designed for NO contacts. Apart from digital pin 2 through pin 13 of Arduino, analogue pin A0 through pin A5 are also used as digital I/O pins to monitor the seven different input conditions.
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