Week 5 - Journal

Task Description:
Design, simulate, and build a simple electronic device that performs two actions. The device may serve a need at your home, or is just fun to build! 

Ideation: "Is it urgent?" device is an attempt to stay focused at work and save the three-mins of my life that my colleagues spend cheating-chat about random work-related or non-related matters. 

By pressing the "push button" the arrow will be rotated by a motor to communicate my availability; the green area is to say "Khadija is here but here" and the red area is to say "Khadija is cheer but not here". 

When the button is pressed the motor will move to the green/red area and the LED light, on the top of the "I" will glow.

Takeaways from the video tutorials: 

This week was about building electrical circuits that have single/multiple components using a breadboard and making them functional. It is advised to use Avometer to troubleshoot problems by performing voltage measurement and continuity tests, and ThinkerCad to simulate the circuits digitally before even building them. 

Electrical circuit components can be divided into the following categories:

• Voltage source: battery (three voltage coin cell) and power adapters (five and nine voltage). 

• Wires: jumpers (male/male - male/female - female/female) and crocodiles - breadboard for wire organizing. 

• Switching devices: on/off switch with different shapes - push buttons. 

• Output components: lamp (light) - buzzer (sound) - electric motor (motion). 

ThinkerCad for simple electrical circuit simulation, or for one that has microcontrollers like Arduino. It is preferable to use color code when wiring; red for positive and black for negative. 

DC Lamp does not have a polarity. According to ohm’s law, the more voltage we have the brighter the bulb will be. It is not recommended to use the maximum voltage that the bulb can handle as this will shorten its life span.

DC motor turns electricity into motion through an internal permanent magnet and it considers to be an output device. The gears inside the motor are the components responsible for controlling the speed of the motor (RPM) and can be increased by using higher voltage.  The voltage range is between three to twelve voltage when should we use high voltage when we apply too much load and if we need to increase the speed of the motor? 

The direction of the rotation will be changed if we change the polarity (clockwise and anti-clockwise). Extra load requires extra current and might lead to the motor burn. 

Buzzer turns electricity to sound (piezo effect). It has polarity and the maximum voltage to handle is eight and the minimum is around three. (maximum voltage is equal to highest sound.

DC fan needs five voltages to rotate and it has polarity.

LED (Light Emitting Diode ) has polarity: the anode (longer) is positive and the cathode (shorter) is negative. Two voltage sources should be the limit it can handle, more than this we will need a resistor to take the extra load.

Ohm’s law is how we calculate the resistor value (R= V/I). We can use a resistor color code calculator to know a value of a resistor in the kit, or simply use google image search if we know the value but we do not know which one we pick from the kit. Resistors do not have polarity. 

Breadboard compact way to minimize the wiring. In the mini breadboard, pins are horizontally connected. A few components are not designed to be attached to the breadboard like the ON/OFF switch so we use crocodile and male jumpers in this cause. 

Potentiometers have three pins and offer an unfixed value resistor by rotating the wipers. It can be attached to a LED light to have variation in brightness or to a buzzer to produce low or high sounds. 

In the series connection, the voltage will be distributed among the components equally and might not be compatible with all of them, and the current will be fixed, unlike the parallel connection which distributes the current and provide all components with full power voltage. It is preferable that we use parallel connect as it creates independent components/ multiple devices meaning that if you decide to remove one of the components the circuit will remain functional. We use a series connection when we connect LED with a resistor and in the case of using an ON/OFF switch.

Avometer is a device used to measure current or volt or resistance mainly for the purpose of troubleshooting or debugging. Usually, we check the wiring before we start the measurement and the continuity test. 

Voltage regulators are used to reducing the input voltage, for example, I have only nine voltage adapters, and the components I am using need only five voltage so I can use the regulator to reduce the voltage. IC refers to the integrated circuit and each regulator has a data sheet that shows the maximum volt it can handle and the pins' names/labels. When we have components that need different power voltages, we use the power supply for the highest value and the regulator for the other component. Why can not we use a resistor in this cause as we did with the LED and the five voltage adaptor because the current will not be enough to run the fan or the motor?  

Steps before fabrication:

• Before starting the design on Thinkercad, I was not really sure about all the components I have in the kit that can also do the same function; I had to compare light (output) components and exclude the RGB LEDs due to the voltage value that need resistors as the other components require higher voltage source. The DC bulb was the one I chose at the end that has no polarity and it will match the DC motor in terms of the power needed. 

• For the switching devices, the selection criteria were not only related to the voltage value but also how it looks. The push button is what I am looking for as this week we only build a simple circuit and I can easily control where the rotation of the motor stops without having a smart controlling board in my circuit. 

• The motor, which can rotate both ways depending on the polarity used, I had to also test it separately with a different power source to check the speed of the motor. 

• I did two versions of the wiring on Thinkercad: one with a series of connections and the other one with a parallel connection as the series connection could not provide the bulb with enough power, however, I have to connect the push button with a series connection at the end. 

https://www.tinkercad.com/things/e5qwv0YMhZT?sharecode=it39KLZCRlNg0O_IqBuAJPHDmHw5DC09UkQD9P8YmHk

Challenges of this week: 

• The shape was really basic so it did not give me so much headache building it, however, I noticed that there are some features I have to consider when building a smart device and one of them is getting access to all components for maintenance. I left the back of the box open but this should not be the case in reality. 

• Another challenge was how to attach the motor to the body in a stable fixed connection. I had to use tape with a glue gun to make it more secure. 

• Last but not least, cardboard was not really friendly when punching a hole in it, I did this carefully with the use of the ruler and caliper to take the right measurements. I used also a circular cutter to cut the first layer then continued the rest by punching a pen into the cardboard. 

Since I am also using a motor in my final project, I do not think I can test the function by only using the cardboard model without actually trying to use the wooden sheets with the ball bearing. It was really hard making the cardboard movable without gluing (unintentionally) the upper layer with the lower body. 

Another insight is related to the distribution of the weight (upper and lower parts) and how this affected the stability of the model. Again, not everything can be tested using the cardboard model but at least the weak points of the design can be spotted easily.