Analog Filters AAAAAAAAAH!! AWWWWWWWWW! Ouuch!

Noise is a real pain especially when you are dealing with signals so weak to speak for themselves. And so are designing filters for them. Searching on the internet I came across a very old IC by Burr-Brown Corp. "UAF42" or the universal filter IC. Now sold by TI. Its a real good IC. you can design all sorts of filter with minimum componets. Comes with a free DOS based software for components calculation. And the best part TI gives free samples :)

http://focus.ti.com/docs/prod/folders/print/uaf42.html

http://focus.ti.com/docs/toolsw/folders/print/filter42.html

Once you get the sofware....these are the steps to follow:

 This is the most important section. Here you enter all the requirements. Depending upon your order of filter number of ICs increase. Now press F3

 The component values here are for a fixed type of circuit. for example here it indicates subcircuit PP3. goto http://www.ti.com/lit/an/sbfa002/sbfa002.pdf and search for PP3 subcircuit diagram.

The above diagram is at page 6 fo the stated pdf

Important notes:

If you are making filters with higher order, more IC are required. In taht case the software with make the circuit as combination many subcircuits. Go through teh datasheet for more details. Enjoy!

Building Autonomous machines / Robots

The world is changing fast and so are the definitions. Robotics, now has so many definitions today, but we still think a robot should look like human and could do more than we can do. Some definitions also say that any machine that can run on its own and make work easier is robot. But than in this case a washing machine is also a robot. Leaving the definitions aside, we would talk about making a very simple autonomous robot today. One that can guide itself and will not need human help in making decisions.

I'm talking about a line follower. A line follower is a machine that can be guided by just a line drawn on its path. Simplest of its kind can be built on a differential drive system, i.e, independent actuators (motors) for each wheel.   Plus we need 2 pair of Light sensors (Tx and Rx).

This image here is of a black line follower. Currently both the sensors are sensing white colour ( A '1'). We can say that M1 and M2 are tied to these sensors and are being driven by them. But when this follower will move a little further, the right sensors will encounter black or a ZERO. Stop the right motor on sensing this, and let the Left motor rotate. This will turn the machine to the left following the line.
There could be more modifications to build a better line follower, which I'll introduce in next post, also I'll introduce how to build the required circuit for it.