Full Wave Lab.docx

M.Qasim

Physics 16

Experiment Make a circuit of full wave rectification by using diode and verify it on oscilloscope Rectification The conversion of Alternating Current (AC) is convert into a Direct Current (DC) is called retification.The circuit which can perform the process of retication is called a rectifier.The diode acts as a rectifier because one way condition property of diode that current flows during forward bias and does not flow in reverse bias.

Types They are of 2 types  Half wave rectifier

 Full wave rectifier

Diagram

Apparatus      

Oscilloscope Full Wave Rectifier Simple connector Diodes Regulated Power supply Transformer

Circuit Diagram

Explanation The conversion of ac signal into unidirectional dc signal in such a way that rectifier converts whole of input waveform to one of constant polarity ( positive or negative ) output is called full wave rectification. The full wave rectifier circuit is used in most rectifier applications because of the advantages it offers.Full wave rectifiers have some fundamental advantages over their half wave rectifier counterparts. The average (DC) output voltage is higher than for half wave, the output of the full wave rectifier has much less ripple than that of the half wave rectifier producing a smoother output waveform.The full wave rectification can be performed by two types of rectifier circuits which are  Centre tapped full wave rectifier  Bridge circuit full wave rectifier

Centre tapped full wave rectifier

Diagram Positve cycle We apply an AC voltage to the input transformer. During the positive half-cycle of the AC voltage, terminal 1 will be positive and terminal 2 will be negative potential. This will lead to forward bias in diode D1 and cause current to flow through it. During this time, diode D2 is in reverse bias and will block current through it.

D2 acts as a open circuit.

Negative cycle

During the negative half-cycle of the input AC voltage, terminal 2 will become positive with relative to terminal 2 and centre-tap. This will lead to forward bias in diode D2 and cause current to flow through it. During this time, diode D1 is in reverse bias and will block current through it.

D1 acts as a open circuit.

Output waveforms

Bridge circuit full wave rectifier A diagram of the basic bridge rectifier circuit is shown below. The circuit has the advantage over the full wave rectifier using a centre tapped transformer that there is no centre tapped transformer requirement and that the both halves of the cycle are used in the winding.

 4 diodes ( D1, D2, D3, D4 ) The four diodes D1, D2, D3, D4 are arranged in series with only two diodes allowing electric current during each half cycle. For example, diodes D1 and D3 are considered as one pair and diodes D2 and D4 are considered as another pair.

 When input AC signal is applied across the bridge rectifier, during the positive half cycle diodes D1 and D3 are forward biased and allows electric current  During the negative half cycle diodes D2 and D4 are forward biased and allows electric current while diodes D1 and D3 are reverse biased and blocks electric current.

Output waveform

Traces on Oscilloscope