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QBar Graph Quickstart Guide



The Basics:



The QBar Graph is composed of an LED Bar Graph, and two resistor networks (for the LEDs).  Basically, this is a bar graph that you can change any time with your code.  In your code, you can light up an individual segment, a few segments, or the whole bar graph.






First off, if you don’t know how to solder, go here to learn the basics so that you are thoroughly prepared to assemble your kit.



Parts in Kit:



Qtechknow QBar Graph PCB (Printed Circuit Board)

LED Bar Graph - Surprise Color

Resistor Networks - 330 Ohm (2)

Male Headers - 14 (two separate pieces of 10 and 4 pins)



Tools Needed to Assemble:



Soldering Iron

Rosin Core Solder

Safety Glasses

Safety Mask

Vice or Third Hand



You will need to get on your own:



Arduino Leonardo with micro-B USB Cable




Arduino Uno with USB-B Cable



When using lead, take precautions like:


  • Make sure to wash your hands with soap and water twice after you solder
  • Don’t eat the solder
  • Don’t touch your face or eyes after touching the solder
  • Wear a mask to prevent the solder smoke to come into your mouth, or to prevent you from inhaling it
  • When working with hot solder, you especially want to wear eye protection


Assembling the Kit:



Take out the QBar Graph PCB out of the the bag and put face up into a vice or third hand.



Insert the LED bar graph into the copper holes corresponding.  Make sure that you are putting it in the right way!  The LED bar graph should have a notch, and it should correspond to the silkscreen outline.




Flip the PCB over and put it back into the vice or third hand face down, so that all of the leads show on the back.   Bend the leads outwards in different directions.



Put your soldering iron on one of the junctions where there is a copper hole, and one of the LED bar graph legs popping through it.



Wait three seconds, and then take your solder, touch it briefly to the junction, and then take your soldering iron away.  The junction should look something like these volcano shapes:



Repeat this process nineteen more times (it will be pretty easy, though!) to the other joints with the copper hole and a LED bar graph leg popping through it.



After you are done, flip the PCB over again so that the text and LED bar graph are facing upwards.



Take your 330 ohm resistor networks out.  In red is where a black dot should be on your resistor network.  This is the GND or ground pin.



Put these into the resistor network pins on the PCB.  Make sure that you are putting it in the right way!  Make sure that you put the side of the resistor network with the black dot in the square hole, indicated in red.



Bend the two outside leads of the resistor network outwards.



Solder the six copper holes that have resistor network pins popping out of them (using the same method as before).  You don't have to use too much solder for these pins, because they are smaller.



Repeat this process twice, to solder both of the resistor networks in.  If you get too much solder on a pin of the resistor network, try reflowing the joint by holding the tip on the joint, and holding it there until the solder flows into the joint.  



Take the 10 pin male header and 4 pin male header, and put them into these Arduino pins:  The 10 pin male header goes into pins SCL through D8, and the 4 pin male header goes into pins D7 through D4 as shown below in the picture.  



Place the QBar Graph on top of these pins.



Solder in place.  But make sure that you don’t put too much solder in, because that can cause the QBar Graph to be permanently installed on your Arduino!



Wait for the QBar Graph to cool off (around 20-30 seconds), then pull out of the Arduino sockets.  Now you are finished soldering your QBar Graph!





If you haven’t downloaded the Arduino IDE, go here to download the latest version.  If you haven’t installed drivers for the Arduino (haven’t downloaded the software yet, or haven’t done this step yet), read the following table:



If you have...

Arduino Uno

Arduino Leonardo


No drivers needed, proceed to the next step

Go here, then proceed


Go here, then proceed

Go here, then proceed


Put in your QBar Graph to your Arduino like this: Put the 10 pin male header into pins SCL through D8, and the 4 pin male header in pins D7 through D4.  



Plug in your Arduino with your USB cable (USB-B on the Arduino UNO or earlier, and USB-microB for Arduino Leonardo) to your computer.  Download this zip file and unzip onto your computer.  If you are on a Mac, double click the folder labeled “FishBank-QBar-Graph-Example-Code-f78ead3”, double-click the file named “QBarGraph.ino”, then press OK when the dialogue box pops up.  If you are on a Windows computer, press Save instead of Open when you press the download button, double click the folder labeled “FishBank-QBar-Graph-Example-Code-f78ead3”, double-click the file named “QBarGraph.ino,” and then press OK in the pop up box.


The Arduino IDE should open up with the QBar Graph 'bounce' sketch.  This sketch will light up the LED segments in a pattern to make it look like it is 'bouncing' back and forth.  


First, make sure to select the board that you are using from Tools > Board.



Then, go into Tools > Serial Port, and select the correct COM/Serial Port.  On a Mac, the usual Serial Port will be /dev/tty.usbmodemfa131.  Any small variation of that will be fine.



On Windows, the COM Port will usually be COM 4, and anything lower or higher might work.


Here are the basic buttons/functions in the Arduino IDE:



Now let’s upload the sketch/code to the Arduino.  Plug one end of the cable into your Arduino, and then the other end into your computer.  Press the Compile + Upload button (Verify if there is any errors in the code, and then upload the sketch/code onto the Arduino), and the program will run on the Arduino.


You should see that the QBar Graph 'bounces' back and forth on your Arduino!


If you have any more questions on this product or how to use it, contact Qtechknow Tech Support at


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