1. (Table and graph) Use the transistor by itself. The goal is to create the graph for IC (y axis) versus VBE (x axis). Connect base and collector. DO NOT EXCEED 1 V for VBE. Make sure you have the required voltage value set before applying it to the base. Transistor might get really hot. Do not TOUCH THE TRANSISTOR! Make sure to get enough data points to graph. (Suggestion: measure for VBE = 0V, 0.5V, and 1V and fill the gaps if necessary by taking extra measurements).
|Ic (mA)||VBE (V)|
Table 1: Shows relationship between Ic Vs. Vbe
Graph 1: Shows relationship IC vs. VBE
2. (Table and graph) Create the graph for IC (y axis) versus VCE (x axis). Vary VCE from 0 V to 5 V. Do this measurement for 3 different VBE values: 0V, 0.7V, and 0.8V.
|Vce (V)||Ic (mA) VBE= 0V||Ic (mA) VBE=.7V||Ic (mA) VBE=.8V|
Table 2: Shows relationship between Ic Vs. Vce
Graph 2:Shows relationship between IC vs VCE
3. (Table) Apply the following bias voltages and fill out the table. How is IC and IB related? Does your data support your theory?
|VBE (V)||VCE (V)||IC (mA)||IB (mA)|
As Ic increases so does Ib. The value of Ib starts so low because the transistor did not begin to allow current until .7 volts. But as soon as it passed that value they both increase at a steady rate.
4. (Table) Explain photocell outputs with different light settings. Create a table for the light conditions and photocell resistance.
Photocell light setting will change drastically with different amounts of light. The higher the amount of light, the higher the output should be, which also means less amount of resistance.
|No light||12 kΩ|
|Room light||1.3 kΩ|
|Flash light||100 Ω|
Table 4: Shows the resistance with different amounts of light
5. (Table) Apply voltage (0 to 5 V with 1 V steps) to DC motor directly and measure the current using the DMM.
|Motor (V)||Current (mA)|
Table 5: Shows the current through the DC motor at different voltages
6. Apply 2 V to the DC motor and measure the current. Repeat this by increasing the load on the DC motor. Slightly pinching the shaft would do the trick.
|Motor (2V)||Current (mA)|
As you increased the amount of load on the motor, the amount of tension increased causing the current to increase.
7. (Video) Create the circuit below (same circuit from week 1). Explain the operation in detail.
Video 1: Shows the circuit and how the amount light powers the photocell
Explanation in the video.
8. Explain R4’s role by changing its value to a smaller and bigger resistors and observing the voltage and the current at the collector of the transistor.
As R4 changes, so does the current. If R4 becomes a stronger resistor, then the current will go down. If R4 decreases in strength, then the current increases. Since resistance and current are inversely proportionate, this makes sense.
9. (Video) Create your own Rube Goldberg setup.
This is the start to our Rube Goldberg circuit. The way its supposed to work is that when the motor is activated the the gears will begin to turn which turns the belt and begins to lift up the platform where the photocell is hidden in the dark, once exposed the photocell should have less resistance which turns on the diode. Unfortunately we were unable to locate a working diode. It is a work in progress but has a lot of promise for the rest of the semester.