Experiment no.2 diode

Experiment NO:2

DIODS

First I would like to explain about diodes . Diode is an electrical device that allowing current flue in one direction with far greater easy than other. The most common type of diodes in modern circuit design is semi conductor diode.And also diode an insulator to

current flow the opposite direction. Diodes are used for regulate voltage, switching applications, current guides, tuning device, circuit mixing can say protect the circuit. There are several types of diodes we have, some of semi conductor diode zener

diode. Dioode Light-emitting diode (LED) and silicon controlled

diode rectifier which we use in a upcoming experiment.
Forward voltage drop.The electricity use up a little average pushing its way through the diode. There is a small voltage across a conducting diode, it’s called forward voltage drop in normal diode about 0.7v.Reverse voltage is applied perfect diode

does not conduct but real diodes leak very tiny current a few ua or less. This can characteristic of silicon diode in the most circuit it would be very small amount of current. In the forward direction most diode have maximum reverse voltage (50v) or more. If this exceeded the diode will fail and a large

current pass in the reverse direction, this is called break down.

Testing Diodes
We can test a diode with a multi meter.Diode must be connected the correct way anod (a) and cathode (k) the cathode is marked by line printed on the body anod (+) and cathode (-). Diodes are level with their code number. In

the next experiment i used rectifier diode (large current) which are used in power supply to convert (AC) to (DC) in alternator also used in circuit where a large current must pass through the device.

Component : 1*diode, 1*LED

	Voltage drop in forward biased direction.	Voltage drop in reverse biased direction.
LED	1.8 v	oL
Diode	0.67 v	0.0L

Explain how you could identify the cathode without a multimetr.

Without meter the cathode (K) side of diode is colure with silver strip.

The LED cathode side is short lead and slight flat on the body of round leads. Inside the LED the cathode is the larger electrode

Component: 1* resistor , 1* diode. 1 LED.

Exercise: For Vs= 5v, R= 1Kohms, D =14700 build the following circuit on a breadboard.

Calculate first the value of current flowing through the diode,now measure and check your answer?

Show working

Calculated                                                                                 Measured

I = V/R = 5-0.7 = 4.3/1000 Ohms = 4.3 mA                                   4.3 mA

The reading is which I expected, because the calculation and the reading is the same , at this experiment i follow the ohms law.

Calculate the voltage drop across the diode, now measure and check your answer?

Calculated                                                                                  Measured

V= I*R= 4.3 mA * 1k Ohms = 4.3                                                   0.65 V

VD = VS - V1 = 5 - 4.3 mA = 0.7 V

The maximum current that can flow through the given diode is 1.0 Amps .

For R= 1Kohms the maximum value of VS so that diode operates in safe region is 

VS = IR      1 * 1000 = 1000 = R = 1K Ohms

Now replace the diode by an LED & calculate the current , then measure and check your answer?

Calculated                                                                                  Measured

A = VR = 5 - 1.8 / 1000 = 3.1 / 1000 = 0.0031 Amps                     3.1 mA

The voltage across diode is less than the voltage drop across LED, so LED has more current flowing then diode.