Sameer Graded

Sameer/Comments.txt

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+1. Your scans are very poor quality and hard to read.
+2. Correctly identified that reliability is so important that price of unit is not important.
+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...
+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: 
+/*
+        ┌───────────┐      ┌────────────┐
+        │ transf.   │      │Linear      │  
+───────►│ rectifier ├─────►│regulator   ├────┐
+        │ filter    │      │7805        │    ▼
+        │           │      │            │    5V Regulated
+        └───────────┘      └────────────┘    VCC
+
+
+
+
+        ┌─────────┐    ┌────────┐   ┌───────────┐    ┌─────────┐
+        │         │    │ Signal │   │Comparator │    │  LEDs   │
+        │Sensor   ├────► Cond.  ├──►│           ├───►│         │
+        │         │    │        │   │           │    │         │
+        └─────────┘    └────────┘   └───────────┘    └─────────┘
+ */
+ 
+ 
+5. Design notes:
+	Opamps cannot driver LEDs and buzzers directly - you need some buffering / current boost - maybe a transistor stage.
+	What kind of components should be chosen? precision resistors, some trimpots / variable Rs to calibrate in the field right?
+	Buzzer will be loud enough when mounted in the same "box"? Why not mount it externally?
+6. Power supply efficiency is poor, which means heat will have to be dissipated. Where is the heat sink / thermal management?
+	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. 
+7. Industrial Design:
+	The environment is humid - what is the plan for keeping the inside of the box free from condensation?
+8. KICAD Design
+	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.
+	LEDs are connected wrongly - they are both in parallel with the buzzer.
+	No decoupling caps for the pwer supply?
+	What is the buzzer current? Won't it sag the power rails?
+	
+	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
+	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.
+	If the buzzer is inside the water-tight housing, will enough sound come out?
+
+9. BOM and Pricing:		
+	Unit pricing seems a little high, but that is ok.
+	Have you accounted for shipping handling, import duty etc?
+	what about cost of assembly - manpower, solder, housing, materials for housing, etc?
+	You said power supply is external, but you have only counted the parts cost.
+	
+