49 lines
3.3 KiB
Plaintext
49 lines
3.3 KiB
Plaintext
1. Your scans are very poor quality and hard to read.
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2. Correctly identified that reliability is so important that price of unit is not important.
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3. Why did you not consider adding some kind of remote signalling? What if the attending person is far away and does not hear the buzzer? Some SMS / wireless based alert would have been good. Also, what about a graded approach - e.g. Alert Level 1 when humidity is 5% outside range, alert level 2 when 10%, etc...
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4. File #2 should have had the blok diagram. You have drawn a mix of circuit and block diagram - even within the power supply for example:
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/*
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┌───────────┐ ┌────────────┐
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│ transf. │ │Linear │
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───────►│ rectifier ├─────►│regulator ├────┐
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│ filter │ │7805 │ ▼
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│ │ │ │ 5V Regulated
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└───────────┘ └────────────┘ VCC
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┌─────────┐ ┌────────┐ ┌───────────┐ ┌─────────┐
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│ │ │ Signal │ │Comparator │ │ LEDs │
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│Sensor ├────► Cond. ├──►│ ├───►│ │
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│ │ │ │ │ │ │ │
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└─────────┘ └────────┘ └───────────┘ └─────────┘
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*/
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5. Design notes:
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Opamps cannot driver LEDs and buzzers directly - you need some buffering / current boost - maybe a transistor stage.
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What kind of components should be chosen? precision resistors, some trimpots / variable Rs to calibrate in the field right?
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Buzzer will be loud enough when mounted in the same "box"? Why not mount it externally?
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6. Power supply efficiency is poor, which means heat will have to be dissipated. Where is the heat sink / thermal management?
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If the power supply does fail, how does it alert the user? There is no power "on" LED to show that the device is awake.
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7. Industrial Design:
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The environment is humid - what is the plan for keeping the inside of the box free from condensation?
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8. KICAD Design
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Schematic: Why choose OPA op amp instead of something more generic like LM328 or LM741 or perhaps OP07? The LM2904 is just Rs4 per piece - this op amp is ~Rs300.
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LEDs are connected wrongly - they are both in parallel with the buzzer.
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No decoupling caps for the pwer supply?
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What is the buzzer current? Won't it sag the power rails?
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Layout: is not compact, could have planned a little better. Also, buzzer and LEDs could have been closer. How do you plan to label the LEDs? Someone walks up
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to the unit whn it is buzzing - how do they know what is the problem? Some kind of labelling should have been mentioned on silk screen or on outer cover.
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If the buzzer is inside the water-tight housing, will enough sound come out?
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9. BOM and Pricing:
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Unit pricing seems a little high, but that is ok.
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Have you accounted for shipping handling, import duty etc?
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what about cost of assembly - manpower, solder, housing, materials for housing, etc?
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You said power supply is external, but you have only counted the parts cost.
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