One of my favourite subjects. The lecturer is fun, and the projects are tough but they are exactly what I like to do. Lucky for me, I did not take this subject in my third year (this subject is a third year subject) but I opted to do it this semester as an elective instead. Last year it was taught by another lecturer, one who wasn’t as fun as my current one. Even so, he’s gonna be teaching us for the second half of the semester. You can’t have everything can you? Hehe.
This year, Graeme (my lecturer) had this great idea of giving us a project that we have full control of. Of course, datelines are controlled by him, just that we have free reign on our project design. We were asked to design an audio amplifier with the following specs:
- operate from a single 15V external power supply
- have input impedance > 10k ohms
- have a 3dB frequency response (nominally) 400Hz – 18kHz
- have mid pass-band voltage gain with magnitude of (nominally) 18
- be capable of driving an (external) 68 ohm load with at least 10Vpk-pk
- AC coupled input and output
Following components are available:
- LM741 op-amp + socket
- 2N3904 (NPN BJT)
- 2N3906 (PNP BJT)
- 1N14148 (small signal diode)
- 47 uF 25V elec. Capacitors
- 68 ohm 0.5 W resistor
- PCB pins
After preliminary design on PSpice, a simulation tool for circuits, I managed to build up a circuit that fit the required categories. Actually implementing it on the breadboard gave me lots of grief though. As usual, a lot of things are idealised in simulations, and this ‘idealisation’ sometimes kills the design. After many optimisation processes, I finally am able to construct a circuit that is barely able to meet all required criterias.
After that stage, PCB design came. Implementation was fairly easy (for me) and I handed in my design last Tuesday. The PCB boards came in on the following Monday (technically yesterday since it’s 12.48am for me now) and I completed soldering the thing that day itself. I have not tested it yet though. *Shudder* Knowing the problems that plagued me when I worked on the breadboard, I hate to think the debugging issues associated with this. Ah well, these are the pics of my completed project on PCB.
PCB is missing the op-amp, which is supposed to sit here: (the op-amp is still on my breadboard) – Finger looks fat (check out the PCB size on the next pic)
Size of the PCB as compared to my Sony Ericsson Z800i. For those who haven’t seen the Z800i, the size of the board is 1.95″ x 1.7″. Use a ruler. Small eh?
Now you know what actually sits in those big ass speakers around :) Implementation and design might be slightly different, but the idea is the same.
KW
Hehe… Finally pictures for my temperature sensor!! Unfortunately i don’t have the luxury of friends taking photos during or after my presentation, so I can’t show you a picture of me in smart clothes. Nevertheless, here’s the project picture. :)
Picture of the components (lower layer):
KW
Hehe thanks so much to Sian Siew for updating my blog theme. The old one was nice, but the column width a little too small to do any serious blogging. (I don’t want my blogs to be merely 3 lines thick =/ )
Ok… Back to topic. Being a final year student, I’m allocated a project to work on. Along with 2 other teammates, our project will be a year long thing with a final year presentation to the public as well to our supervisors.
Project Name: High Speed Vision System. Project code: RC2 (RC standing for Robocup). Below is a project description by Robert Li, one of my group members:
“One of the most important aspects of a robot is its sensing/vision system.
This project is to realise sophisticated object recognition algorithm on hardware which is designed to be used on robotic platform but will also be compatible with a board range of industry applications. Highly accurate ball tracking and moving target recognition at high speeds is the ultimate goal of this project.
By using a high resolution video camera and a specially designed mirror, robots are able to “see†a 360 degree image (essentially a top down view of a defined area). A Field Programmable Gate Array (FPGA) is used as a primary mean of speeding up the process of object detection. It’s extraordinary concurrent processing feature allows processing different coloured objects simultaneously and pipeline processing each pixel as it comes into system. External Synchronous RAMs are used to support large volume of data while maintaining high speeds.”
Since we were needed to submit our own project descriptions, I believe the text above neatly summarises our project aims in a nutshell. That being said, the complexity of it is enormous as we are going to integrate the algorithm into hardware (the algorithm being realised last year by a group of students, Ni Ma and Nathan Williams. Their project website: http://fpga-vision.sourceforge.net/
Current issues that we are addressing:
- Bus size to interface with the processor board. (which is managed by Boon Chong Khor, Nicholas Seng Tatt Yeoh and Shubham)
- Building our very own development PCB board since the RAM chips used in the stock dev board is DDR-RAM and we’ll be using SRAM.
- Timing issues with processing frames ‘as they come’ (hence high speed) as well as application consideration (the speed which is required by the application)
The vision system that we will develop will ultimately be used in the robots that are representing my university in future Robocup tournaments. As I go along with the project, I will post some pictures of our progress as well as the actual robot itself.
