Abhijit Kshirsagar
2 years ago
1 changed files with 39 additions and 0 deletions
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Name: Swakath |
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1. Question text: |
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Design a system using this Honeywell ammonia sensor (https://drive.google.com/file/d/164WvPD7GauvseOfH-K3v8iZ4YYmQFkq-/view?usp=sharing ) to detect when ammonia concentration in ambient atmosphere exceeds 100 ppm an alert an operator in a control room about 100m away. This device will be mounted in various sections of an industrial processing plant. The complete plant will need a fairly large number (~20) of sensors so unit costs needs to be kept under control. Also, once mounted it will be very difficult to remove/service/repair the sensing devices. |
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2. Design summary: |
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Overall approach is fine. |
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Good work finding th module that has a 4-20mA output directly |
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3. Block diagram |
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Why is there a common supply for both the sensor module and the receiver module? |
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They might be physically very far apart! |
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4. Power supply design |
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The brick module may end up being underpowered for what you need. |
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Also, why design a rectifier filter and then use the module? |
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Power in a current-driven system is indeed tricky - you need to factor in the worst case |
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voltage drop and times the current is power. |
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5. Industrial Design: |
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6. KICAD Design |
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Schematic: |
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All good - good use of decoupling caps. |
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No Power on LED? |
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How exactly is the fault opamp working? |
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Also the OpAmp outputs are +/-12V. If you're connecting this to the uC you need to scale down to 5V or 3v3. |
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PCB: |
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No Mounting holes? |
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Good use of pours |
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7. Pricing / BOM / Assembly |
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The question asked for 2 prototypes - meaning two systems with about 20 sensor modules each. |
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But I guess this interpretation is fine too. |
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