Topics mentioned in this week
-A.C. and D.C.
-Using multi-meter
-Building circuit on breadboard (LM386 amplifier), base on the schematics here
*Classwork: Building circuit on breadboard, remember to show me the finished circuitry to me and make sure I've marked it on the record.
A.C. and D.C.
Alternate current
As the name suggests, the direction of current flows in this kind of circuit alternate all the times. it is usually indicated by "Hz", you can see it on the information on the fluorescent lamp. In Hong Kong the frequency of A.C. is 50Hz.
The image below shows the direction of current
Direct current
Opposite to direct current, current flow in D.C. are stable, thus there's always a "+" and "-" side for battery. The image below shows how current flow in D.C.
Using multi-meter
Most multi-meter can measure Voltage (A.C. and D.C.), Current (D.C.), Resistance and continuity. Images below shows how these values could be measured using multi-meter. By turning the central knob to the corresponding position, you can do the measurement easily.
Voltage measurement (D.C.)
Voltage measurement (A.C.)
Current (D.C.)
Resistance
Continuity
Beware when reading the unit, when there's a "k" or "m" on the corresponding position. The reading on the digital meter should also be read with that unit. For instance, when the knob is turned to 20k for resistance, and the reading is 0.123kΩ which means the resistance of the object/resistor is 123Ω.
Breadboard
Breadboard is used for building prototype of circuit. The structure of a breadboard is illustrated in the image below.
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