October 5th, 2022

## Lab: Using a Transistor to Control High Current Loads with an Arduino

As suggested, I tried simplifying the code down and just worked with the transistor before adding in the potentiometer and motor directed in the lab.

The lecture in class on transistors and relays really solidified my understanding of how these components work. Using that understanding and visualizing how current runs through the transistor helped a lot in figuring out how to program and wire just the transistor on its own.

I’m also realizing how much of a visual learner I am. The diagrams we do in class have been very helpful. I know Jeff suggested drawing schematic diagrams of our circuits, but I always have a hard time knowing how to do it and figuring out where to start, especially when faced with circuits of building complexity. However, seeing the benefit of the diagrams in this week’s labs and overall trying to find what works for me (i.e., simplifying code and wiring) motivates me to try adding in simple schematic diagrams.

I found Jeff’s suggestions to simplify and work with just the components very helpful and plan on approaching new material in this way.

### Connect a Motor and a Power Supply

I continued by checking to see if the motor works with the transistor.

IMG_6920.MOV

Why does ground/black wire of the motor go to the transistor instead of the voltage/red wire? I would assume that the black wire connects to ground, while the red wire connects to voltage through the transistor, which also controls the flow of current to the motor. However, when I tested the assumption by connecting the red wire to the transistor, it didn’t work. I also tried connecting the red wire to ground and kept the black wire connected to the transistor, which also didn’t work. I tested the second configuration in the case that my assumption about the color interpretation for the motor wires were wrong, and black is for voltage while red is for ground.

Why do I need 1N400x diode? What function is the 1N400x serving?

1N400x Diode, Collector to Ground

1N400x Diode, Collector to Ground

1N400x Diode, Collector to Voltage

1N400x Diode, Collector to Voltage

Even though my motor was running the code with no error, I attached a 1N400x Diode because I saw the lab manual also doing it. When I connected the diode from the collector pin to the ground bus on my breadboard, the motor ran continuously and did not perform the delays. When I connected the diode from the collector pin to the voltage bus, there were no noticeable changes in how the motor was running the code I programed.

1N400x Diode, Collector to Ground

1N400x Diode, Collector to Ground

1N400x Diode, Collector to Voltage

1N400x Diode, Collector to Voltage

I also noted that the lab specified connecting the anode of the diode to both the ground and collector pin (presumably a type where one of the anode is supposed to refer to the cathode), but regardless, I couldn’t really tell which side of the diode was the anode. In these two clips, I tried flipping the 1N400x diode and tried seeing if there was a difference in how the motor would behave. When connected to the voltage bus, the motor moved much slower. However, when connected to the ground bus, there was not much difference.

It’s entirely possible that this isn’t the right part. Although the component looks similar to the visual representation on the lab manual, the specific part is labeled 1N4006 instead of 1N400x.