Thursday, September 17, 2015

How to add intelligence to our homes? - Part 2

This is the long overdue update of the house project conceptualized a while back with my kids.  In this project, a model house was wired for simple lighting using LED's.
The USB home
Each part or room in the model house will be lit by a dedicated LED and each LED will be directly connected to the pins of the microcontroller, in this case, the Arduino Uno.
The Arduino Uno wired using a recycled IDE cable

The Arduino being wired
The Arduino will act as a hardware controller/driver to power up the LED's but commands will come from a PC.  This whole architecture can be ported to a real, full sized house and control is not limited to lighting only but for the purposes of demonstration, the model house should be sufficient to illustrate.
The GUI in a Windows PC

The GUI showing the check boxes and sliders as control inputs

The model home is connected to the PC via the USB port.  The Uno will function as a slave unit with the PC as the master.  If a user clicks on the GUI, the corresponding LED will light up (or toggle off) in the actual model home.  This therefore illustrates how a real USB controlled home can be made possible.

The power through

Power lines
High tension power wires bring electrical energy across vast distances for distribution to the end users.  They play as the major energy conduits of today's civilizations.  With the advent of information technology, the world's hunger for electrical power became even more resounding.  So what makes this system work?

1.  AC is used instead of DC.  AC allows voltage transformation.  This means that the voltage can be varied with the use of a device called a transformer.  A higher voltage is used for transmission versus the lower voltage used in distribution.  Why is this so?  This leads us to point number 2.

2.  As power (P) is the product of voltage (E) and current (I), for the same power transmitted, the current can be lower by using higher voltage (P= IE).  A lower current means smaller diameter transmission cables.  This translates to lower investment costs for the cables.

3.  The consequence of higher voltage however is the difficulty of isolation or insulation.  If the cables are too near each other, it can cause arcing much like a lightning bolt.  Thus the cables are raised high above ground and are spaced far apart enough.

Modern electrical transmission systems are more complex than it seems.  There is normallty a grid designed to take in power from many source generators and distribute the power across multiple load points.  All these complications are taken cared of by engineers so that we can live our lives comfortably and with all the power we need.