Sunday, August 19, 2007

The flight of a capacitor...

Last year of graduation, full of excitement and fun. The funniest thing is the group project. Being electrical engineers, we had chosen to conceptualise a smart home where every electrical appliance would behave as if it is a concious energy conserving human being. We had designed the circuits to build energy conserving attitude in all the electrical appliances in the home. While I won't drill down into the technical details of the endeavour, I wish to tell the story of one of the circuit components - the capacitor.

Cooling fan is almost inevitable in every house in an equatorial country like India. With it comes the fan speed regulation. We had a temperature sensor which was to be incorporated in a voltage control circuit which would eventually control the speed of the fan. This way it would keep the fan speed regulated as per the temperature and would avoid unnecessary usage of the fan(and conserve the energy). One of the electronic components to be used in the circuit was the capacitor(polarized). As most of you might know, the polarized capacitor has two legs, which serve as two opposite polarity plugs to connect the capacitor in the circuit. The rule of thumb is the positive of polarized capacitor should go to the input(positive of the source) and the negative should go to either ground or output(negative of the source). The capacitor has a certain voltage rating and it would never let the excess voltage(than its rating) to be built across the network in its presence. Ours was a small 12V capacitor and was a little corrupt in the sense that it used to build only 11.5V instead of 12V keeping 0.5V for itself. Days are bad, even capacitors are not honest. While wondering about why the capacitor might turn traitor, once I misadvertently plugged it with the opposite polarity. That means, negative to the input and positive to the ground. Without noticing this blunder, we completed the rest of the circuit and were very happy to have it ready for testing. Till then, that capacitor was thinking of taking a revenge on me. Afterall it was a great insult to it, I plugged its input to output and output to input. Okay, so the circuit was ready and we were enthusiastic to test it immediately(at 10:00PM). I was standing just next to the test board, cuz I had to take several voltage and current readings on the ammeter. My pal Kiran was my accomplice at the moment. Confirming that everything was in place, I gave a green to Kiran and he switched the circuit on and Bingo....the capacitor sensed that this is the time to inflict the most damage. With a missile's determination, it left the test board and blasted directly and exactly at the center of my right cheek. What a serious blow on my untainted reputation!! Since then I was always wary of this violent creature. For the next three weeks I was teased by my cronies for so many reasons and in so many different ways. I was so ashamed to explain the incident and people were wondering - who kissed on my right cheek so violently(my reputation was tainted in that sense too).