Wien Bridge Op Amp Oscillator

This paper (lab report) is also in french, I’ll translate it soon. The maths are obvious though (transfer functions, gain, etc…)

It can be read or downloaded here         (case sensitive link)

The files (Multisim & LT Spice) are here:

For the other reports

For any feedback, correction, addition, feel free to comment.


Op Amp Signal Generator

This college paper is in french for now (April 7th, 2012) like the previous one. I’ll translate it as soon as possible.

This one is about signal generating (ramp). There is a part where I didn’t count the voltage drop of the two zener diodes (when they are direct biased), so you’ll have to include that.

You can read it directly or download it from :

The files for the simulation and the schematics (LT Spice & Multisim are here:

For all the other reports:

Multivibrators with NE 555 (Astable & Monostable)

This college paper (lab report) is in french for now (April 7th 2012), I’ll translate it as soon as I find some time.

It’s pretty much detailed, 11 pages talking about monostable and astable modes, with schematics, and ways to tweak the duty cycle. (making an astable with 50% duty cycle), reducing and eliminating the recovery time in monostable mode, etc…

You can either read it or download it from here:

You can find all my reports here : .

PCB Etching Tank With Temperature Control & Bubbly Bubbles..

This is a college project, I opened a thread about that on detailing the things to be done and getting great feedback, spot on advice.

The thread is here :

The main points are:

-The heart and brain of it will be a 16F88, it has got an Analog to Digital Converter which is very handy, for I’ll be using an LM135 (temperature sensor) and maybe I’ll have a pressure sensor for volume.

-Aquarium heater & pump. For temperature and agitating the fluid (to increase reaction speed).

All remaining details are in that thread, and I’ll update it when I get some things done.

How To Share Your Internet Connection on VirtualBox: Ubuntu Guest on a Windows XP Host

This was very frustrating for me. Really frustrating. I searched on different fora but nothing worked.

First, you need to have some sort of benchmark. For me, it was being able to connect to the Speedtouch modem (Gateway). If you can’t even connect to the modem, there is a problem.

To know the IP address of your gateway on Windows, execute a “tracert” in the command prompt, and it will be the first IP on the list. Or “ipconfig /all” and search for it. Most likely

Here is the configuration which worked for me.

On the left panel of VirtualBox, click on “Settings”. Then “Network”.

You will find a drop box called “Attached to”, chose “Bridged Adapter”..

Just below, you will find “Name”. For me, it was “Intel(R) PRO/100 VE Network Connection”. Chose “Allow All” in “Promiscuous mode” and check “Cable connected”. And then OK.

It doesn’t matter if your guest box is running or not. If it’s not, launch it. If it is, go to the upper right corner of your screen, you will find two arrows.

Click on that icon, and then click on “Connection Information”.

Do it again and click on “Edit Connections”.

Click on whatever connection is offering itself to you, usually it is “Auto  Ethernet” or “Wired Connection 1” or “eth0”. Double-click on it, or click on it, and then click on “Edit”.

Click on the “IPv4 Settings” tab.

In “Method”, chose “Manual” instead of “Automatic (DHCP)”

In “Netmask”, enter “”. (Without the quotes)

In “Address”, chose an IP address. For example “” (Without the quotes).

In the “DNS servers” tab, you will enter a list of IP addresses separated by commas. For example, you can enter,  (Which are two of the OpenDNS IP addresses). You can add more if you wish. I added two others that are proper to my ISP. Don’t forget to separate IPs with commas.

You will have something like this

Click on “Save” and close the other window. Click on the two arrows and then click on the name of your connection. This should disconnect you and reconnect you.

You should be done. Open a browser and try If it doesn’t work, try your Gateway’s IP address. If this doesn’t work, you probably got it wrong or your cable is disconencted OR you can go to VirtualBox, click “File” then “Preferences”, “Network” and tinker with the parameters there.

If there’s still a problem, feel free to comment here and we can work things out.

The Operational Amplifier In Commutation

This discusses the operational amplifier in commutation (monostable and astable configurations more precisely).

It also contains a part about reducing the recovery time in the monostable, and the effect of an impulse while it is in the unstable state.

The paper is in English, here’s the link (Rev 5):

There’s a French version I’ll upload later,



Stepper Motor Control Using PIC16F84A & ULN2003 – v1.5 – TEC 585


This is a very simple circuit and  its code (PIC Assembly)

Here are EAGLE3D images of the board (TOP & Bottom)


Notice how good looking this board is. Compare it with the ugliness of my  first (embarrassing) board.

Due to the gear used in the university lab, I had to increase the width of the tracks to 50 mils, and make big fat Pads. I had to Edit the libraries of every component to make big Pads, as when I used the standard ones and etched the board, I totally ate away the pads copper when I drilled. Actually, fine tracks aren’t that much of a problem, but PADS are.

Note to self: Don’t be afraid to super-size.

The one without varnish is the second one, but then I did one more iteration (I was wrong in the tactile switch) and got a last one which was varnished.

The tactile/push-buttons that were available didn’t have their library in Eagle, so I had to create them (it’s .3 inches long and .2 inches wide). I had some problems doing that, but I was helped on the ETO forum. (Thanks Inquisitive).

You’ll notice on the TOP view that there are some missing parts.

You can download the whole project (.rar archive containing Eagle schematics & custom libraries + board files + .asm source code): HERE

The two ports are pulled high via a 10K resistor (9.8K on the actual board), and each sequence is launched as soon as we pull the pin down (held down).

PORTB is configured as output, RB0 through RB3 go into a ULN2003 7 Darlington Array, outputs of the ULN go to the stepper motor.