91.548 Robots
Assignment
Paper
Assignment No. 1
Due Date:
Course: 91.548 Robots 2003 Spring
Student: Jianping Zhou
Instructor: Prof. Fred Matin
1. Go through the lab kits from the 91.305 class and test the functionality of the dev board (using the checklist).
By following the checklist, my working UML91.305 development board was tested and functions with all checked.
2. Read Chapter 1 of The Art of Electronics Student
Manual, including the in-class notes, the lab, and the worked examples.
Chapter 1 of The art of electronic student manual introduces several very basic fundamentals of analog circuit. The introduced electronic components include resistors, capacitors, RC, LC, filter, Diode, and power supply circuits. This chapter demonstrates Ohm’s Law, Kirchhoff’s Law, Thevenin Model. The concept and calculation of equivalent resistance, input and output impedance, and voltage divider are covered in this chapter. The experimental equipments, such as voltmeter, oscilloscope, are also mentioned.
The two CHI ACM articles: PegBlock: a Learning Aid for the elementary Classroom and Pinwheels: Visualizing information of flow in an Architectural Space demonstrate two very successful and interactive system with the purpose of education and entertainment. They give us much inspiration of how to use robotic technology to develop educational and attractive device.
The manual of UML 91.305 Development Board gives a detailed description about how this board provides useful features for basic digital logic circuit prototyping.
3. Investigate V= IR with the limited test equipment you
have available (i.e., shared oscilloscopes). Measure the voltages on the
batteries. Build voltage divider circuits and measure the voltages across the
different legs.
This experiment was made on following circuit. The purpose of different resistor R is for getting different current flowing through 10Ω resistor in order to verify the Ohm’s Law working on it (assuming those resistors obey ohm’s law). The R also demonstrates the effect of voltage divider by looking at the measured voltage VB.
|
R |
VAB(V) |
VB(V) |
I cal (mA) (VB / R) |
VA(V) |
|
0 |
2.35 |
|
|
4.74 |
|
60 Ω |
0.81 |
4.03 |
67.1 |
4.91 |
|
333 Ω |
0.14 |
4.78 |
14.4 |
4.93 |
|
500 Ω |
0.09 |
4.85 |
9.7 |
4.94 |
|
1 K |
0.05 |
4.90 |
4.9 |
4.95 |
|
10 K |
0 |
4.96 |
0.5 |
4.96 |
The linear feature of drawn VAB - I cal curve demonstrate the 10Ω resistor almost obeys the Ohm’s Law in the relationship V = IR.
Another fact of the 4.8% (4.74v – 4.97v) variation of measured volt source VA under different R suggests the volt source is just a fairly good one. Actually the UML91.305 Dev Board does nothing to improve its volt source, just simply uses alkaline battery.
4. Refer to Experiment 1–3 on page 27. Rather than plotting the VI curve of a diode, plot the curve for the light bulb in your lab kit. Measure at least four voltage/current points, including one with full brightness (approx 60 ma), one with the lamp dim, and one with no light at all. Characterize the graph.
The experiment was made on following circuit.
|
R |
VAB(V) |
VB(V) |
I cal(mA) (VAB / R) |
Itest(mA) |
Light |
|
10 Ω |
0.56 |
4.34 |
56.0 |
56.7 |
On |
|
60 Ω |
2.51 |
2.50 |
41.8 |
41.0 |
Dim |
|
333 Ω |
4.81 |
0.62 |
1.86 |
13.9 |
Off |
|
500 Ω |
5.02 |
0.13 |
0.26 |
9.7 |
Off |
|
1 K |
5.11 |
0.05 |
0.05 |
4.9 |
Off |
The VB - I cal curve of lamp shows the lamp does not obey the Ohm’s Law
In this exercise, I used digital multimeter TENMA 72-4025 to measure voltages. The digital meters usually have better performance to measure voltage than current. By comparing the measured currents of this exercise with the calculated ones (assuming the used resistors obey the Ohm’s Law), the differences especially for bigger resistor citations indicate that using digital ampmeter to measure the current in this case is not appropriate.
5. Understand basic NPN transistors used as a switch.
Figure out how to get a 7400 series chip to drive an NPN transistor and thereby
turn a lamp on and off.
NPN transistor can function switching on a device
connected to its E or C port by sending a faint control current t into its B
port. The following circuit uses a N-and gate of 7400 chip to code two input
signals, the encoded signal control NPN to drive on or off a lamp.
The circuit of this exercise is as follows:
|
R1 |
R2 |
VBC (V) |
IAC (mA) (VBC / R2) |
VDE |
IDE (mA) (VDE / R1) |
VAB (V) |
|
10Ω |
0 |
|
|
0.40v |
40.0 |
4.74 |
|
10Ω |
10Ω |
0.55 |
55.0 |
0.40v |
40.0 |
4.19 |
|
10Ω |
30Ω |
1.46 |
48.6 |
0.40v |
40.0 |
3.30 |
|
10Ω |
60Ω
|
2.13 |
35.5 |
0.40v |
40.0 |
2.64 |
|
10Ω |
333
Ω |
4.57 |
13.7 |
0.41v |
41.0 |
0.28 |
|
10Ω |
500
Ω |
4.74 |
9.0 |
0.41v |
41.0 |
0.11 |
|
10Ω |
1K |
4.83 |
4.83 |
0.41v |
41.0 |
0.05 |
|
10Ω |
10K |
4.88 |
0.5 |
0.41v |
41.0 |
0 |
|
500
Ω |
0 |
|
|
3.70 |
7.4 |
4.8 |
|
500
Ω |
10Ω |
0.56 |
56.0 |
3.70 |
7.4 |
4.26 |
|
500
Ω |
30Ω |
1.47 |
49.0 |
3.73 |
7.5 |
3.36 |
|
500
Ω |
60Ω
|
2.44 |
40.7 |
3.75 |
7.5 |
2.42 |
|
500
Ω |
333
Ω |
4.74 |
14.2 |
3.81 |
7.6 |
0.24 |
|
500
Ω |
500
Ω |
4.86 |
9.7 |
3.82 |
7.6 |
0.12 |
|
500
Ω |
1K |
4.93 |
4.93 |
3.84 |
7.7 |
0.05 |
|
500
Ω |
10K |
4.99 |
0.5 |
3.86 |
7.7 |
0 |
|
10
K |
0 |
|
|
4.13 |
0.4 |
3.82 |
|
10
K |
10Ω |
0.49 |
49.0 |
4.13 |
0.4 |
3.51 |
|
10
K |
30Ω |
1.36 |
45.3 |
4.14 |
0.4 |
2.69 |
|
10
K |
60Ω
|
2.36 |
39.3 |
4.15 |
0.4 |
2.29 |
|
10
K |
333
Ω |
4.62 |
13.8 |
4.23 |
0.4 |
0.29 |
|
10
K |
500
Ω |
4.81 |
9.6 |
4.26 |
0.4 |
0.11 |
|
10
K |
1K |
4.92 |
4.92 |
4.27 |
0.4 |
0.05 |
|
10
K |
10K |
5.02 |
0.5 |
4.34 |
0.4 |
0 |
The curve VAB - IAC shows the lamp feature, which almost matches the curve got from exercise 4, and consequently concludes the same result.
6. Experiment with various DC motors in the lab. Figure out how much current they draw under no load and full load (that is, stalled).
In this experiment, by using a 10 Ω resistor shown in the following circuit, and measuring voltages on its both sides under no load and full load conditions, we can calculate the currents drawn by the DC motor under respective condition based on ohm’s law, which is applicable to the 10 Ω resistor.
|
R |
No Load |
Full Load (stalled) |
||||
|
VB
|
VAB
|
I cal (VAB / R) |
VB
|
VAB
|
I cal (VAB / R) |
|
|
10 Ω |
5.08v |
0.08v |
8.0mA |
4.80v |
0.3v |
30.0mA |
|
10 K |
5.18v |
0 |
0 |
5.18v |
0 |
0 |
Through the experiment we can see that the current drawn by motor increases with the increase of motor output torque (saying from no load to full load). We also know the voltage drop on the motor decreases with the increase of motor output torque; apparently this doesn’t obey ohm’s law.
7. Under controlled conditions, blow up at least one of: LED, transistor, or electrolytic capacitor. Do NOT blow up a tantalum capacitor unless you want to pay me $2 to replace it.
When directly applied UML305dev ideal volt source 5V to LED, it immediately was blew up. This is because the maximum allowed current of LED is about only 2mA, its resistance is small enough to make the passing current under 5V exceed 2mA.
8. Do something else cool with the parts in the lab kits and around the lab.