Tuesday, 15 March 2011

Practical Workbook. Experiments on resistors, diodes and capacitors.




Experiment1
 Resistor Colour Code helps to identify resistors; and several simple circuits in series and parallel connection refreshed the Ohm's Law application. I've found that even funny proverb helps to keep in mind row of numbers and write down tha table of resistors value . It's easy to remember and can be usful.






From the table above which is based on the resistor value calculations and experimental measurements I concluded that only one resistor failed because of poor quality.


Experiment2-Experiment4
All our experiments on diodes from the practical workbook showed that voltage drop across diodes is essential feature of this electronics components.Applying this for the calculation from the data sheet or measuring this in particular circuit and studying diagram we can read the whole picture about what is happening with electrical signal at the moment.
Another fundamental rule which is known as  Kirchhoff's current law we applied in Experiment 3.
Along with Kirchhoff's voltage law and voltage drop these are three the most offten applicable rules for circuit reading in electrical and electronics engeenering.








R= (Vs-Vz)/Is; Is=Iz+Il  where Iz from the data sheet. Il=Vz/Rl.




V1=Vz; V2=Vknee(0.7v or 0.6 v depending on the diode properties) and V4=Vs-Vz-V2.


Experiment5 The experiment on the capacitors not only reminded us that this device is used for timing but also demonstrated how the charging time can be changed. The smaller resistor rating the faster capacitor will be charged. Once the capacitor was changed onto the bigger one the charging time increased. The patterns on the oscilloscope screen demonstrate how the charging process goes. It's easier to see 5 stages as well as percentages of charge. The hihger charge the longer it takes because it's harder to move electrons.
Depending on the capasitors construction charge can be stored either for a long time or for a while due to leakage.
R*C*5=T where R is resistance in Ohms, C is capacitance in Farads and T is time in seconds.















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