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USER MAUAL FOR : L C R BOARD

AIM: - To study the series and parallel resonance circuit and to find frequency and quality factor.

MICRO BOARD COSISTS OF: -Set of resistors, Capacitors, Inductors and Milli ammeter.R = 150 R = 150 R = 330

C = 0.01 C = 0.1 F C = 0.22 FL = 2.5mH L = 5mH L = 7.5mH

PROCEDURE: -

SERIES RESOACE: -

1. Connect the circuit as shown in the circuit diagram.2. Apply input signal using signal generator. The output should be 10V only.3. Take the output across the resistor and feed it to Ammeter input sockets.4. Vary the frequency till the Ammeter records a sharp rise and fall, adjust the signal such

that the Ammeter deflection is the maximum possible. This is the resonant frequency of

the connected combination of the circuit.5. Adjust the signal generator amplitude such that to get full-scale deflection. In Ammeter

now reduce the frequency till the deflection falls considerably. Then increase thefrequency in regular intervals & note down the Ammeter readings.

6. Plot a graph between the meter deflection divisions and frequency.7. Repeat the procedure using different combinations of L, C & R and study how Q is

affected. Also study how Resonant Frequency depends upon different combination ofL.C.R.

PARALLEL RESOACE: -

1. Connect the circuit as per the circuit diagram.2. Apply input signal, from a reliable signal generator. The output should be 10V only.3. Take the output across the tank circuit and connect to Ammeter input sockets.4. Vary the frequency till the Ammeter records sharp fall. Adjust the signal such that the

deflection falls down considerably. Then increase the frequency in regular intervals andnote down the deflection.

5. Adjust the signal generators amplitude such that, to get full-scale deflection. Now reducethe frequency till the deflection falls down considerably. Then increase the frequency inregular intervals & note down the deflection.

6. Plot graph between the meter deflection divisions and frequency.7. Repeat the procedure for different values of R and study how Q is affected. Also study

how resonant frequency depends on different combinations of L.C.R.

CALCULATIOS: -

For series circuit Z is minimum at Resonance.

Resonance frequency of series circuit is-

1fo = Zo = R + Ro

2 LC

Io = E

R + RoEo = RIo

Ro is the resistance of the coil.

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foQo = ( = f2 f1)

f2 is the point beyond the fo (at the point Eo/2)

f1 is the point before fo (at the point Eo/2)

LWoQ is also equal to =

R + Ro

For parallel circuit Z is maximum at resonance.

1

fo =2 LC

LZo = or Qo =L Wo

CRo

EZoEo = Izo =

(R + Zo)

foQo = (=f2 - f1 as like the case of series circuit)

CIRCUIT DIAGRAM: -

L C R SERIES RESOACE GRAPH: -

L C R PARALLEL RESOACE GRAPH: -

R

L C

Im

ImI

2

f1 f0 f2FREQUECY

R

A

+

A

-

L

CI

f0

FREQUECY

SIGALGEERATOR

SIGAL

GEERATOR