Sensors are used to monitor the pressure and the temperature of a chemical solution stored in a vat.

Question

Sensors are used to monitor the pressure and the temperature of a chemical solution stored in a vat. The circuitry for each sensor produces a HIGH voltage when a specified maximum value is exceeded. An alarm requiring a LOW voltage input must be activated when either the pressure or the temperature is excessive. Design a circuit for this application.

Answer 1

1. Each sensor provides a HIGH voltage output when its respective value (pressure or temperature) exceeds the maximum.
2. This HIGH sensor output is fed into a NOT gate (inverter) to convert it to a LOW voltage if conditions are excessive (i.e., normal sensor voltage is HIGH).
3. The outputs of the two inverters are then connected to the inputs of an OR gate.
4. The OR gate's function is to output a HIGH signal if either of its inputs is HIGH. In this case, it would be HIGH when either of the original sensors are within their normal range (meaning their inverted signals are LOW).
5. The output of the OR gate is then fed into another NOT gate. 
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7. This final NOT gate converts the OR gate's HIGH output (when both conditions are normal) into a LOW voltage. 
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9. The alarm requires a LOW voltage input to activate, so it will be triggered by this final LOW output, indicating that the normal conditions are no longer met.