diff --git a/Balu/Comments.txt b/Balu/Comments.txt new file mode 100644 index 0000000..ea0cd67 --- /dev/null +++ b/Balu/Comments.txt @@ -0,0 +1,26 @@ +Balu Mahesh +1. Design a system using a conductive water sensor (basically two metal probes that are very close together - when water is present between the probes it conducts) to detect when water level in a tank falls below 20% and when that happens, turn on a pump. The pump is a 3-phase 3-wire 1kW rated. This is for an industrial application where the water is being used for a chemical process. Design the system with some fail-safe such that the tank should never become empty. + +2. Design summary is ok but could have been a little more detailed. Where is the fail-safe to prevent the tank from being completely empty? + How do you prevent overflow? How do you prevent the motor from running when input supply is not present? What about when the pump fails? + Basically there is no mention of the failsafe requirement. + What are the tadeoffs? How are you balancing cost, efficiency, and reliability? + What is the meaning of "Zero PCB or card board"? + +3. Block diagram: what is roof of the tank? The top of the tank? Or is the tank on the roof of a building? + The block diagram is confusing: what is the meaning of "exception?" Which of thse lines are signal and which are power?? + +4. Power supply design is totally absent. + +5. Industrial Design: + Your text is directly lifted from https://sg.rs-online.com/web/c/enclosures-server-racks/enclosures/pcb-mounting-enclosures/ + +6. KICAD Design + Schematic: + Did you use this circuit? even the values are identical: https://easyelectronicsproject.com/wp-content/uploads/2020/10/Water-Pump-Auto-Switch-Pic-12.jpg?x56667 + + PCB: + Layout seems ok + DRC is not passing because there is no outline. + +7. Pricing / Assembly: Items costs are ok although grossly underestimated. No mention of materials for the actual probes, wiring, etc ??? diff --git a/Lokesh/Comments.txt b/Lokesh/Comments.txt new file mode 100644 index 0000000..e21363f --- /dev/null +++ b/Lokesh/Comments.txt @@ -0,0 +1,41 @@ +Name: Lokesh + +1. Question text: + 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. + +2. Design summary: + Your design is well thought out. Using the cascaded power supply for local boards and wireless link to control room is also a good point. + In reality you will have to check if the industry allows wireless, which bands, or whether they want some MODbus type system. + One major issue in your design is that you are using a FET as the frontend - how will you account for variations in the FET gm? Each board + will have a different gain which you need to calibrate. Similarly each sensor has a different gain and sensitivity which you need to calibrate, + you should have mentioned that. + + +3. Block diagram + Block diagram is fine. + Some details are missing - for example what are the protocols / signal levels between the boards? + What happens when multiple sensors go off - are there some ways to tell the control room wchich sensors have gone off? + Or how many? + + +4. Power supply design + Why have you chosen a rectifier supply? Can you not choose an off the shelf switching sypply? + Are you gonig to supply different PSU for every different voltage level in industry? + +5. Industrial Design: + Mostly ok - dimensioning could be better. Also, are there wires coming out of the box? + Or are there connectors on the edge? or are there some cable glands? + +6. KICAD Design + Schematic: + Major flaw in circuit design - your 5V regulated is not ground referenced. So any noise / disturbance in the power line will make it into the output. + + PCB: + Board outline is missing and DRC fails + Why mix SMT and THT components? Also interesting that your THT components are on the back. Why? + Some unconnected stubs on your board - e.g. + +7. Pricing / Assembly