Archives: March 2015

Update for the week of March 15 – March 21

On Tuesday, we finished our connection from the main PCB to the Arduino shield. Originally, we were going to to striped the IDE ribbon cable and solder it on the Arduino shield. However, we found out the wires are to weak to be secured on the shield. Instead, we connected the IDE ribbon cable to a IDE socket on the shield. This is more secured and easier to disassemble and reassemble the connection.  In addition, we purchased a 3 meter long L shaped aluminum from the machine shop and attached to our platform as it will be our side guard.

 

On Thursday, we fully tested our PCB circuit with all components attached to it. It is fully functional, however, we need to re-collaborate our scale to obtain a new equation. Furthermore, we also received our ramp from the machine shop. We still need to buy the side guard for the ramp and  multiple hinges to attached the ramp to the base.

 

On Saturday, we finished the design for our circuit box and attached it to the pole. We also filmed the remaining part of our video. We still need to put in some ppt slides in the video, and we are expecting to be done by next Tuesday. In addition, we also started preparing the draft for poster, and it will be sent by next Tuesday.

 

 

 

 

 

Today, we also received our ramp from the machine shop

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Update for the week of March 8 – March 14

On Tuesday, we met with Navid, and gave him the following updates.

  • We will be filming our client while he answer our questions on Thursday
  • the ramp is still in progress
  • the components we bought on last Thursday
  • we will be making the holes on the box for LCD, push button and the toggle switch at the machine shop

On the same day, we went to machine shop and asked Mark for a sheet of metal that we will be covering our platform. We decided not to bend the metal, as we don’t have the proper machine that is able to do this. Instead, we will be covering the side with other material. Therefore, Mark cut the metal with a size of 800mm*1200mm. This cost of metal will be charged to our Capstone financial account directly.

After we received our invoice for the platform we had made in the machine shop. The cost was $80 for 2.5 hours of work, which brings our running total to $618.65. This does not include the ramp we are having made, or the sheet of metal we purchased from the machine shop today, since we have not been charged for those items yet. We expect to be charged another $100 for them. We also estimate that we will need another $150 for miscellaneous items such as material to cover the sides of the scale, metal to cover the ramp, sideguards, etc. Therefore, we asked the department for budget extension.

On Thursday, we met with our client and film him while he answers the following questions:

  1. Please introduce yourself.
  2. Describe who Tetra is and what they do.
  3. Why did you suggest this project to UBC?
  4. How do you think not weighing yourself can affect your health?

On the same day, we received our PCB. So we started to test the PCB one part by one part, making sure there is no short circuit or mistake. We found one mistake regarding the size of the INA. The holes for INA are too far apart. So the INA IC wont able to fit in. We solved this mistake by stacking a “right size” socket to a bigger socket which can fit into the holes. We also soldered the socket for LCD, LCD driver, IDE, and regulator.  In addition, we received a email respond from Professor Gopalakrishnan, asking for a list of the things we bought, and the things we are buying.

On Saturday, we tested the PCB with adapter, power button, INA, and the platform with the load cell, and it showed the signal has successfully being amplified. In addition, we started making our video. It is almost done. We still need to put our final product into the video.  Our budget extension has approved by the department!!!

 

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Update for the week of March 1 – March 7

On Tuesday, we met with Navid to inform him our progress:

– The PCB has been send for fabrication.

-Some suggestions regarding how to assemble the PCB were given.

  • Solder the PCB parts by parts
  • test if there is short circuit between ground and vcc
  • put the ICs after
  • it’s better to use socket than soldering the ICs directly to PCB

On the same day, we discussed our storyboard and decided the basic idea how we are going to film our video, and also decided the questions we are going to ask our client during filming.

On Thursday, we obtained the legs for our platform, and we then started to design our ramp with a height of 8.5 cm. After discuss with Mark, some designed techniques were given. Therefore, we designed the ramp with three right triangles as a stand, and a piece of a wood on top of its hypotenuse. It reduced the weight and the material used.

On the same day, we went to Lee’s Electronic after our short meeting at school. We purchased the following items:

  • plastic box for our circuitry
  • socket for LCD, regulator, and INA
  • Arduino prtotosheild
  • Solder iron

 

 

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Update for the week of February 23 – March 1

On Tuesday we met with Navid to follow up with the progress of our project. The following were discussion in the meeting :

– Address certain issues regarding about the PCB. Navid suggested that we the connector to connect all the inputs and outputs to the Adruino instead of the ATMega chip because instability and noise from the surrounding may raise concerns with the signals transmitted between the micro controller chip and the other parts of the circuit.

– To have both parts ( Main PCB and LCD PCB) to be designed on the same PCB board.

– Heat sink for power regulator- In case of too much heat dissipation due to high power, a small metal piece may be considered to be added behind the voltage regulator chip. Current has to be measured to know the power dissipated.

-Traces on the PCB to have minimum clearance of 0.4mm.

-Holes to be at least 1mm and pads to be 2mm.

We have also screwed both (top and bottom) layers of the platform.

On Friday, WengFei has scheduled with Navid to go through the PCB design again before sending it off for fabrication. Minor changes to the circuit has done and has been finalized by the end of the day.

On Saturday, PCB was ordered and the designed was sent to 3PCB in China for fabrication. The manufacturing of the PCB will take about 2-3 days and an additional few days for shipping.

 

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