For the third and fourth activity in my TCOM 121.2 Telecommunications laboratory class, I asked the students to prepare a 200 gain (46 dB) audio amplifier using the LM386 with a bandwidth of 20-20kHz.
I required the students to perform simulations by creating a SPICE netlist. The learning curve required is very steep to meet a 1-2 week deadline for performing the activity. I pointed them to the sci.electronics.cad Usenet newsgroup to search from the SPICE .subckt model since the IC cannot be found by default in the library components of MultiSim or Electronics Workbench. There were sample demonstrations on how to generate the netlist and use the model file using LTSpice in the laboratory. My classes’ were very resourceful. To accomodate the steep learning curve, they were able to find an LTSpice symbol associated with the LM386 subckt model and was able to generate simulations using the conventional schematic capture method.
They implemented their audio amplifier circuits on a standard issued prototyping breadboard. Some were able to get gains of up to 190+ but others are still struggling to exceed a 3dB gain (hence the lab extension). After reaching the 43-46 dB gain milestone, they celebrated their accomplishment by playing with the circuit. Most of the students plugged the output of the amplifier to a speaker. Thus sounds were produced based on the frequency input in the function generator. One of my students, Dale Dy played a rendition of “Happy Birthday” using various frequencies from our signal generator and his groups’ LM386 Audio Amplifier:
I just arrived in our department from a VoIP appreciation seminar in the Advanced Science and Technology Institute (ASTI). Sir Paul, our secretary said that Dr. Toby Dayrit (the Dean) is looking for some faculty in the ECCE department to explain the relationship of the probability of being struck by lightning by wearing an iPod. Apparently all our PhD faculty were not yet available so they sent me (Yay!).
An article was posted in the Manila Standard and in other online news sites. Sol Aragones of ABS-CBN News interviewed me to shed some light. My blockmate, Gim uploded snippet of the TV Patrol report on YouTube.
Sol said I speak in Filipino because TV Patrol is a show for the masses. I was very tempted to say nadagitab (to be electrocuted). Just as the news article said, electronic/ conductive devices in your body excarbate the damage done by being struck by lightning. I also gave a precautionary message about being in lightning prone areas. Avoid them during stormy weather specially today in the Philippine’s rainy season. To get out in case of such a situation (e.g an open field), drop and lie down to decrease your probability of being struck by lightning.
Edit: The report seemed to stress that there is an increased probability in getting hit by lighting when one has an electronic device (e.g. an iPod). There is no correlation between the two. If you are in a open field, most likely you will be struck by lightning whether you are wearing an iPod or not.
Thank you to Dr. Dayrit who referred the Electronics, Computer and Communications Engineering Department’s knowledge and Sir Paul for sending me to the Dean’s office.
For my CE 21 class. The problem discussed earlier was, draw a triangle of stars given the length for a side of the triangle n. It can be illustrated as follows for n = 3.
*
* *
* * *
The next task is to center the triangle:
*
* *
* * *
Then we want to be able to print a diamond
*
* *
* * *
* *
*
This C++ code is one of the solutions to the problem:
#include <iostream>
int main()
{
int n;
std::cin >> n;
int i = 1;
// upper triangle
while( i <= n )
{
int space = n - i;
for(int j = 1 ; j <= space ; j++ )
{
std::cout << " ";
}
int j = 1;
while( j <= i )
{
std::cout << "* ";
j++;
}
std::cout << std::endl;
i++;
}
// lower triangle
i = n - 1;
while( i >= 1 )
{
int space = n - i;
for(int j = 1 ; j <= space ; j++ )
{
std::cout << " ";
}
int j = 1;
while( j <= i )
{
std::cout << "* ";
j++;
}
std::cout << std::endl;
i--;
}
return 0;}
For the homework, answer the Challenge section of the lecture slides on iterations:
Draw a pine tree with 3 sections
Each section should have n lines of stars
The start of the next section should have one less star than the end of the previous section
cThese are installation instructions for my CE 21: Introduction to Computing class so that students will be able to install the compilers on their systems at home.
Download the following files from the MinGW website:
MSYS-1.0.10.exe
binutils-2.16.91-20060119-1.tar.gz
gcc-core-3.4.2-20040916-1.tar.gz
gcc-g++-3.4.2-20040916-1.tar.gz
mingw-runtime-3.12.tar.gz
w32api-3.9.tar.gz
Assuming that the students downloaded them on their desktop as described in the screenshot above, the video below shows the details of installing MSYS. Take note the the installation directory is c:\msys and not c:\msys\1.0.
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