Build Instructions

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• 1

  Parts list

  Magnets - each clock needs 8

   https://www.amazon.com/gp/product/B097HBZ39T/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

  Rubber Bands

  https://www.amazon.com/dp/B07849G52M?psc=1&ref=ppx_yo2ov_dt_b_product_details

  Aligator clips  (used to connect to the meters) - each clock needs 2

  https://www.amazon.com/gp/product/B09RZHCXX7/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1
  

  Silicone feet -  each clock needs 4

  https://www.amazon.com/gp/product/B087MG3G76/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1
  

  Arduino shield board - each clock needs 1

  https://www.amazon.com/dp/B01J1KM3RM?psc=1&ref=ppx_yo2ov_dt_b_product_details
  

  1/8x12x12 plywood - each clock uses 2 sheets

  https://www.amazon.com/dp/B08NC1WRW7?psc=1&ref=ppx_yo2ov_dt_b_product_details
  

  USB charging wart - each clock uses 1

  https://www.amazon.com/dp/B08T98K2LG?psc=1&ref=ppx_yo2ov_dt_b_product_details
  

  Arduino header pins - each clock will use one piece

  https://www.amazon.com/HiLetgo-20pcs-2-54mm-Single-Header/dp/B07R5QDL8D/ref=sr_1_2?crid=2N5FP0KH8FTK9&keywords=arduino+header+pins&qid=1708297732&sprefix=arduino+hea%2Caps%2C92&sr=8-2-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1
  

  Analog meter - each clock will use two

  https://www.amazon.com/dp/B01KDVU1N6?psc=1&ref=ppx_yo2ov_dt_b_product_details
  

  Wire connectors - each clock will use 6

  https://www.amazon.com/dp/B01EV70C78?psc=1&ref=ppx_yo2ov_dt_b_product_details
  

  DS3231 RTC clock module - each clock will need 1

  https://www.amazon.com/dp/B01N1LZSK3?psc=1&ref=ppx_yo2ov_dt_b_product_details
  

  USB cable 10ft - each clock will need 1

       this was the hardest part to find and keep the cost manageable.  The cable needs to be long so that you can put the clock on a shelf etc.

  https://www.monoprice.com/product?p_id=39920
  

  Faceplate material - White/Black - each sheet will support 10 faceplates

  https://www.amazon.com/gp/product/B0C4KYKB1N/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&th=1
  

  5k resistor - each clock will need 2

  https://www.amazon.com/EDGELEC-Resistor-Tolerance-Resistance-Optional/dp/B07HDFN3NV/ref=sr_1_3?crid=2AAXXCX0KQADS&dib=eyJ2IjoiMSJ9.CCOgdXyX4u5AoxvlMvOLJne8BV-BmNPdQknAq9fOUxJC1cmIDRsXUkzvCrF1tso7RdbPypec2-GFn2SCvIn8LcL6MCzdtNjLctQ8dA3fPqWrMY0SHVK1S_B2LHehh-L07BdO5CMCBPN67FO0-LA4vZ6DmBmoKg1obw0ZTx9ZPMWL6rIUR8dh8hfKfeUiFMl4v12yhZwuHaSDiEOwp4jelplUQp-Tu_cN1AWftrityaU.jLFlvv0t85Vtrkdxde5eUpkxHWIIB8RB7rrxt-QASPo&dib_tag=se&keywords=5k+resistor&qid=1708360780&sprefix=5k+r%2Caps%2C331&sr=8-3

   or  you can do 2 10k resistors in parallel   ( this is the option I did, I had better results with accuracy of the meters, and it was good practice soldering for the kids.  This was the first thing I had them solder - each clock would need 4

  https://www.amazon.com/Resistor-Tolerance-Resistors-Limiting-Certificated/dp/B08QRJZ82J/ref=sr_1_2?crid=22LM4XW3PIHEM&dib=eyJ2IjoiMSJ9.ZFTY_8RiZZgLi8YFfNVaHIHp9LajwdWlTYMUZSKljY8KLQV9E25Etr_y-yw_ibsxpMw0BFqorClcL3kAqTgfKYKoSI_cUJf-1y_Sua9vHpBvHP1LtqLvQK18QPz6Tdqd85hduY_7Bd6MWhTcmF5Cb7JPUYU_Yw2CoQk1O8dyOt-C6JljldHrNWYyoO0WKc3tnjR6Y1monwU5WKBhJ_I6e775WGJkV6EytyJqTdAQqzw.HX9moY9nTc9Xm67JgNMaUulCgf11dvUF9VY7PL0blZ0&dib_tag=se&keywords=10k+resistor&qid=1708360892&sprefix=10k+resistor%2Caps%2C115&sr=8-2-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1
  

  The clock can be built in 4 or 5 meetings with kids.  Recommend ages 10 - 18.  Younger kids will need more help.  One person can handle 8 - 10, with more you will need some help

• 2

  First meeting

  The clock can be built in 4 or 5 meetings with kids.  Recommend ages 10 - 18.  Younger kids will need more help.  One person can handle 8 - 10, with more you will need some help

  First meeting

      1.  I talk about what an Arduino is and what it can and can't do.  I have a white board and list  this.  One area it can't do it "time"

      2.  I think introduce the RTC module and explain that it has a watch battery and a crystal and keeps time.   At this point I bring up how does the Arduino talk to the RTC module?

          This is when I bring up the I2C bus.  and how each module on the bus is required to have a unique number.

     3.  Then its time to talk about the meters, again I list Pro/Cons on white board

             Pro -  Nice clean look

                      Don't cost to much

                      Easy to work with

             Con -  They will not work with the Arduino out of the box

                        Need to change the faceplate  (the original faceplate, 0 - 30v)

       4.  This is when I take one apart and show everyone the resistor inside, and I explain what it does.   I show measuring the original resistor with a multimeter, and let them all see the measurement.

               I explain that the Arduino wants to work at 5v.  I introduce Ohms law.

                I do the calculations on the white board.

        5.  I have everyone take one meter a part (only do one at a time).  IMPORTANT make sure they keep the screws in the plastic cover they take off, and tell everyone its important not to lose them.

        6.  I have everyone cut out the original resistor.  I show them how to do it first, cut close to the resistor so you have points to solder on to.

       7.   Ohms law says to use a 5k resistor.  I used 2 x 10k resistors.  I explain that if we put resistors in parallel their value is cut in half.  So 2 10k equals 5k.   I show measuring 2 10k resistors that have been soldered together and the value being 5k.  Then I have them solder the 2 10k resistors together.  I have three soldering irons and helping hands.  For many of them this will be the first time soldering.  This is great first time easy to do and builds confidence.

      8.  I then show them how to solder in the 2 10k resistors.  I explain why we "tin" things and how it helps.   Soldering in the new resistor is a bit tricky, tight spot.  This can take some time.  I didn't get all the meters done the first night.

      9.  encourage them to ask questions.

     10.  I only hand out the two meters the first night.   I remind them to bring these back for the next meeting and that they should keep them in a box or bag

• 3

  Second meeting

  Second meeting

    1.  Hand out the Arduino, RTC module, wires, alligator clips, USB power block and USB cable

  2.  I ask them how we are going to have the Arduino control the meters ?  I explain what PWM signal is and how we can use it.  I draw a PWM signal on the white board.

  3.  I then give a demonstration with an Arduino, RTC and Oscilloscope.  First I show them how to connect the Arduino to a computer.  I explain what a IDE is and why we need it.  I tell them it's easy to use and free to download (I also send out email with the download and how to setup).  I show them how to select the board and the port.  Then show them test code I have to PWM.  I walk through the code, asking them questions while I do (the goal is to have them ask you questions).   

  4.  I then explain that the oscilloscope will show us the actual signal that is being sent.  I connect the Oscope.   At this point we have the code running (it cycles through 0 to 100%), the meter needle is moving and the Oscope wave form is changing.   An area of confusion is often around the time being 0 - 12 hours and 0 - 60 minutes and the PWM values being 0 - 254.  I had good luck talking about conversions between Fahrenheit and Celsius temperature.  I ask them if they want the meter to be in the middle, 6 hours or 30 min what PWM value would then need.  They give different answers and I show the updating the code and sending it and then we watch the results.

  5.  RTC module.  First we are going to connect it with wires and then on another day we will solder it to a shield board.  I have a print out of the pins I show them.  I tell them the module supports 3.3v or 5v, we are going to use 3.3v.  I ask them can they find 3.3v on their arduino.  I do the same for ground.  Then I have them connect these, I tell them its good practice to use Red color for power and Black for ground.  Then it's time for I2C bus, I explain there are only two wires SCL and SDA again I ask if they can find these on the Arduino.  Then I have them connect these wires.  

  6.  I then  explain that we need to set the time.  I talk about many different ways this could be done.  I tell them for this project we are going to take the "Easy Way" and we are going to set it from the code.  We talk about how we could have buttons to do this, and this would be a great follow on project.  I challenged someone to do this, and I offered to help ( I told them I would design a new box for the buttons).  I showed them the commented out code in the setup section.  I explained that the different parameters and importantly when this section of code would run.  I asked them what happens if we turn the power off and back on again.......  It time setting would run again and set the wrong time.   Then we set the time and immediately commented this line out and uploaded.

  7.  I then showed them how the serial console works and talked about how the serial.print and serial.println worked.  I told them they could use this to check on their program.  I showed them some examples of printing out to the serial console.

  8.  Finally I had them look at the information being sent to the serial console.  I asked them if they could tell what part of the code it was coming from, main or the function.

  9.  I gave everyone the final code.   I gove them to programs 

         1.  Test code for PWM

         2.  Final code

  I told them for home work to see if they could get both meters working with the PWM test code.

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