Wednesday, January 20

biscuit-tin-alarm




Someone is stealing the biscuits! Your mission, should you choose to accept it, is to design a circuit which will give an audible alarm as soon as the biscuit tin is opened. The circuit provides a delay of around 10 seconds when the power supply is first connected during which the circuit can be placed in the tin. After this, if the LDR is exposed to light the alarm is triggered and remains ON, producing a penetrating high pitched sound until the power is disconnected.
Prototype board testing leads eventually to a complete circuit for the device being developed. You can continue to make small alterations until the circuit behaves in the way you want.

The sensor detects the opening of the tin. The output of the sensor triggers the latch so that its output goes HIGH. The reset subsystem provides some way of silencing the alarm.

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