Wednesday, July 22, 2009

ROBOCOM electronic team (day1)

Last night,I attended my first ROBOCOM meeting at Power Lab (7pm-9pm).Honestly,I felt so noob when I first went because I realised I have many things that I dont know and I felt a little ashame yet willing to start learning from zero.The class was conducted by a senior student named CS.However after class,I learned many things and I would like to summarize everything I learned yesterday to share with all engineering students.

Realization 1
First of all,what is a test pen?
Test pen is use to measure voltage of an element in an electronic circuit.Take note,when you use a test pen,remember to put at least one finger on the top of the test pen.This is to ensure that there will be a reference voltage level which is the ground.The voltage at ground is assumed to be zero(abitary value).
Do you know?
When measuring a normal switch,don't poke at the wrong 3 holes right?? poke at the hole which is live!!!..usually on the bottom right..otherwise,the values measured are always zero.

Realization 2
Generally,a multimeter can be used to measure voltage,current,resistance (ohm is pronounce as "ohh-hemm"),test for short circuit/small resistance,voltage drop,produce a small signal with very low frequency,capacitance(nowadays seldom to have this function).

Realization 3
What's the difference between electrical potential and difference potential???Remember,both units are also in voltage(V).
Electrical potential is the voltage at any point of a circuit with respect to a refernce point (usually ground).Potential difference is the difference in potential between two points.Current will only flow when there is a potential difference.

And does an LED lights up when our voltage is 500V???Will it over burn???Why???
The answer is Yes and No because LED is current depedent.It only depends on current and current only.Therefore,it depends on the value of resistor we connect to it.

Realization 4
How to understand V=IR easier???
Just imagine V=IR as a mountain with water fall.The height of the mountain is V while I is the current flow of the water.R can be the rocks at the waterfall.
Take note,that's why current is theelement that kill people and not voltage.Height doesnt kill.At what height from ground you stand you wont die.But no matter what height you stand,as long as u are at a point where the water flows,when the flow water is large,u will did.So larger flow=die faster!!!
p/s:larger area exposure will cause resistance to become lower.don't save a person who is touching a current element.

Realization 5
Grounding is very important.It serves as a reference level to measure potential difference.

Realization 6
Decoupling is to disconnect an element from a circuit.
Eg. That's why during analog communication assignment we have many decoupling capacitor.Since we need DC current only,we apply a capacitor which is connected to the ground.Capacitor only allows AC current to pass through.
Remember,current will take the route where distance=shorter,resistance=lower.

Realization 6
How to read resistor values???
Basically,a resistor will have 4 slots with colours.
No1,no2,no3 and tolerance , no1=number 1,no2=number2,no3=number of zeros
So just follow this sequence..

Realization 7
How about capacitor??? No1,no2,no3 also.. same as resistor..but the values are always in pF.Behind sometimes got J,K and etc..those are temperature coefficent. (in %)
Also..the availability of capacitor values in the market can be refer to E6..and the values are 1,1.5,2.2,3.3,4.7,6.8 and 10... ><

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