you have to implement and demonstrate the use of the relay as a circuit element. Sensor is needed to detect a physical v

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you have to implement and demonstrate the use of the relay as a circuit element. Sensor is needed to detect a physical variable, a comparator stage are also needed for designing to take the decision. The output stage should use a relay to trigger the output. for the prototype,
-Output signal should be seen or heard.
- AC signals are not allowed to be used
-5V relays are allowed to be used .
What are the risk analysis may be for