Day 3 - Experiment No.5 and 6 Capacitor and Transistor

Theory
Capacitor

Capacitors consist of two plates separated by an insulator. When voltage is applied, a charge builds up on the plates. Capacitors are often used to dampen voltage spikes, or to time electronic events. Within the automotive world, capacitors are often called condensors.

Capacitors take time to charge. The charge time is dependent on the resistor and the size of the capacitor.

Transistor
Transistors are the active elements that do most of the work in circuits. Transistors act like potentiometers but instead of your hand's turning the shaft, a signal does. Transistors are marked by part number. Some of them have numbers starting with 2N.
There are two kinds of transistors which are npn transistor and pnp transistor.
1. npn transistor

pin2-1: 0.701V
pin2-3: 0.71V
the voltage of pin2-3 is greater than pin1-2 so pin3 is emitter and pin1 is collector.




2. pnp transistor

pin1-2: 0.700V
pin3-2: 0.705V
the voltage of pin3-2 is greater than pin1-2 so pin3 is emitter and pin1 is collector.



3. How can we test a transistor and identify each pin?
6 tests can be done on the 3 terminals.

Part No: TIP32C (Texus Instruments Power)
pnp transistor

pin3-1: 0.609V
pin2-1: 0.608V
pin2-3: 0L
pin3-2: 0L
pin1-3: 0L
pin1-2: 0L
pin4-1: 0.608V
pin2-4: 0 Ω













Rule of thumb -
TIP32C PNP(even number)
TIP31C NPN(odd number)

 

Experiment No.5 Capacitor

Exercise: First, calculate how much time it would take to charge up the capacitor. Then, connect the circuit as shown above. Measure the time taken by the capacitor to reach the applied voltage on an oscilloscope. Fill in the chart below. Also draw the observed waveforms in the graphs below, filling the details on each one.

Circuit No	Capacitance	Resistance(KΩ)	Calculated Time(ms)	Observed Time(ms)
1	100	1	500	500
2	100	0.1	50	50
3	100	0.47	235	235
4	330	1	1650	1650

Label the axis of each graph:

Circuit 1: Capacitance 100uF, Resistance 1kΩ

Circuit 2: Capacitance 100uF, Resistance 100Ω

Circuit 3: Capacitance 100uF, Resistance 470Ω

Circuit 4: Capacitance 330uF, Resistance 1KΩ

How does changes in the resistor affect the charging time?
The more large resistor, it takes more time to charge.

How does changes in the capacitor affect the charging time?
Capacitors take time to charge. The charge time is dependent on the resistor and the size of the capacitor. The larger size capacitors, it takes more time to charge.
Experiment No.6 Meter check of a transistor

Diode test (V) meter readings
Transistor number	VBE	VEB	VBC	VCB	VCE	VEC
NPN	0.732V	0L	0.726V	0L	0L	0L
PNP	0L	0.732V	0L	0.730V	0L	0L