Department of Electronics Engineering Circuit Simulation
CIRCUIT SIMULATION USING PROTES
Department of Electronics Engg., P.V.P.I.T., Budhgaon
can observe the simulation of circuit & analyse the waveforms taken across capacitor C2. Astable multivibrator has no stable state. It generates square wave of predetermined frequency. Hence it is a square wave generator.
Department of Electronics Engg., P.V.P.I.T., Budhgaon
Dr. V. P. Shetkari Shikshan Mandal’s
Padmabhooshan Vasantraodada Patil Institute of Technology,
Budhgaon-416304
Department of Electronics Engineering
Circuit Simulation
Experiment No. : 08 Name of Experiment: Roll Number : Date Performed : Date Checked : Signature (Batch In-charge)Department of Electronics Engg., P.V.P.I.T., Budhgaon Aim:
Design & stimulate the Astable Multivibrator using 555.
Objectives:
To understand principal of working of Astable Multivibrator.
To understand the circuit arrangement of Astable Multivibrator
To study Astable Multivibrator using IC 555.
To understand the procedure of ―Astable Multivibrator using IC 555‖ circuit using proteus.
To observe the simulation of circuit.
Outcomes:
Able to study Astable Multivibrator using IC 555.
Able to understand the circuit arrangement of Astable Multivibrator
Able to understand the procedure of ―Astable Multivibrator using IC 555‖ circuit using proteus.
Able to observe the simulation of circuit.
Programme Education Objective (PEO) Satisfied : 2,3
To enable student to analyse solve electronics engineering problem by applying basic principles of mathematics , sciences and engineering and also be able to use modern engineering techniques , skills and tools to fulfill social needs
To enable to innovate , design and develop a variety of electronic and computer based components and system for applications including signal processing , communication , computer network and control system.
Department of Electronics Engg., P.V.P.I.T., Budhgaon Introduction:
Astable Multivibrator can be designed by using 555 timer IC, Op Amps and also using transistors. The 555 IC provide accurate time delay from mille seconds to hours. The frequency of oscillation can be controlled manually by simple modification. It suitable for circuit designers with a relatively stable, cheap, and user-friendly integrated circuit for both monostableandAstableapplications.
The 555 timer IC was first introduced around 1971 by the Signetics Corporation as the SE555/NE555. This is a simple 555 timer circuit project.
Astable Multivibrator is simply an oscillator circuit that produces continuous pulses. The frequency can be controlled by changing the values of R1, R2 and C1. You can construct
Astable multivibrator using transistors also, but the 555 circuit is comparatively simple.
we have to design the Astable Multivibrator using proteus. It is easy to design on the proteus.
The Astable multivibrator generates a square wave, the period of which is determined by the circuit external to IC 555. The Astable multivibrator does not require any external trigger to change the state of the output. Hence the name free running oscillator. The time during which the output is either high or low is determined by the two resistors and a capacitor which are externally connected to the 555 timer.
Department of Electronics Engg., P.V.P.I.T., Budhgaon INTERNAL DIAGRAM OF IC 555
Department of Electronics Engg., P.V.P.I.T., Budhgaon Circuit arrangement:
The circuit arrangement of Astable Multivibrator as shown in fig. It uses one IC 555 as an Astable multivibrator. In this type of arrangement two resistors and two capacitors are used, the output is taken across pin no 3 of IC 555 as shown in figure.
Theory:
The circuit diagram for the Astable multivibrator using IC 555 is shown here. The astable multivibrator generates a square wave, the period of which is determined by the circuit external to IC 555. The Astable multivibrator does not require any external trigger to change the state of the output. Hence the name free running oscillator. The time during which the output is either high or low is determined by the two resistors and a capacitor which are externally connected to the 555 timer.
The above figure shows the 555 timer connected as an Astable multivibrator. Initially when the output is high capacitor C starts charging towards Vcc through RA and RB. However as soon as the voltage across the capacitor equals 2/3 Vcc ,
comparator1 triggers the flip-flop and the output switches to low state.
Now capacitor C discharges through RB and the transistor Q1. When voltage across C equals 1/3 Vcc, comparator 2‘s output triggers the flip- flop and the output goes high. Then the cycle repeats. The capacitor is periodically charged and discharged between 2/3 Vcc and 1/3 Vcc respectively. The time during which the capacitor charges from 1/3 Vcc to 2/3 Vcc is equal to the time the output remains high and is given by
Tc =0.693(RA+RB)C
Where, RA and RB are in ohms and C is in Farads. Similarly the time during which the capacitor discharges from 2/3 Vcc to 1/3 Vcc is equal to the time the output is low and is given by
td =0.693(RB) C
Thus the total time period of the output waveform is T=td+td=0.693(RA+2RB) C
Therefore the frequency of oscillation f=1/T=1.45/ (RA+2RB) C
Department of Electronics Engg., P.V.P.I.T., Budhgaon
The Astable multivibrator generates a square wave, the period of which is determined by the circuit external to IC 555. The Astable multivibrator does not require any external trigger to change the state of the output. The time during which the output is either high or low is determined by the two resistors and a capacitor which are externally connected to the 555 timer.
Consider the flip flop is initially cleared, when the power is switched on, then the output of inverter will be HIGH.
Now the capacitor C1 starts charging through R1 and R2. (Discharge transistor Q1 is OFF)
When the capacitor voltage exceeds 2/3 Vcc, the upper comparator output will be High, it Reset the control flip flop.
So the Q output of control flip flop will be LOW and Q‘ will be High. So the final output from Inverter is LOW
At the same time, the discharge transistor Q1 turns ON and the capacitor starts discharge through R2
When the capacitor voltage less than 1/3 Vcc, the lower comparator output will be high, then the control flip flop get set to High. (Q=1, Q‘=0, Final output=1)
Now the discharge transistor Q1 if OFF and then capacitor starts charging. This process continues.
The LED connected at the output will glows according to the output status.
4th pin is Reset pin, a Low voltage at this pin resets the IC. The Low signal is applied to the base terminal of reset transistor Q2. Then it turns ON followed by Discharge capacitor Q1 and capacitor discharges.
Department of Electronics Engg., P.V.P.I.T., Budhgaon
Charging Discharging
Resetting
Advantages and Disadvantages of Astable Multivibrator:
(i)Advantages:
1. It is easy and quick to design an Astable using a 555 (also easy to troubleshoot). 2. The 555 timer can source or sink large amounts of current (some handle200mA). 3. It may require fewer devices or connections (1 IC, a cap and two resistors). 4. The 555 may have less frequency drift with temperature changes. 5. Some 555 timers have a wide input voltage range (3.5 to 18V). 555s have a large frequency range.
(ii)Disadvantages:
1.A disadvantage of the 555 is a poor rise and fall time which may cause problems for some edge-triggered devices.
Department of Electronics Engg., P.V.P.I.T., Budhgaon
Name Description Number of
components required RES Resistor 2 CAP Capacitor 2 555 Timer 1 VDC Dc voltage source 1 GND Ground 3 Specifications:
The most important characteristics which are required to be specified for a circuit are given below :
Supply voltage (VCC) 4.5 to 15 V
Supply current (VCC = +5 V) 3 to 6 mA
Supply current (VCC = +15 V) 10 to 15 mA
Output current (maximum) 200 mA Maximum Power dissipation 600 mW Operating temperature 0 to 70 °C
Department of Electronics Engg., P.V.P.I.T., Budhgaon Procedure using Proteus:
1. From main page of Proteus, click on ‗P‘ to click device from library.
2. In pick device, insert the component which has to be selected & click on ‗OK‘. 3. Then place the all components on the Proteus screen.
4. Right clik the component properties to change the required value 5. Add voltage probe at input and output of diagram.
6. Select the graph mode & choose AC sweep analysis option
7. Right click in the graph window and elect add traces(input & output trace). 8. Right click & activate simulate graph
9. Observe input & output waveforms and analysis the results.
CIRCUIT SIMULATION
Department of Electronics Engg., P.V.P.I.T., Budhgaon Conclusion:
We can understand the working of Astable Multivibrator as well as the detailed circuit of IC 555.By using proteus we can observe the simulation of circuit & study the waveforms taken across pin no.3 of IC 555.
Department of Electronics Engg., P.V.P.I.T., Budhgaon
Dr. V. P. Shetkari Shikshan Mandal’s
Padmabhooshan Vasantraodada Patil Institute of Technology,
Budhgaon-416304
Department of Electronics Engineering
Circuit Simulation
Experiment No. : 09 Name of Experiment: Roll Number : Date Performed : Date Checked : Signature (Batch In-charge)Department of Electronics Engg., P.V.P.I.T., Budhgaon Aim:
To simulate RC circuit (low pass filter) using Ac sweep analysis. Objectives:
• To understand principal of working of RC circuit. • To understand the circuit arrangement of RC circuit. • To study simple RC circuit using Ac sweep analysis.
• To understand the procedure of simple RC circuit using Ac sweep circuit using proteus.
• To observe the simulation of circuit.
Outcomes:
• Able to understand principal of working of simple RC circuit. • Able to understand the circuit arrangement of simple RC circuit. • Able to study simple RC circuit using Ac sweep analysis.
• Able to understand the procedure of simple Rc circuit using Ac sweep analysis circuit using proteus.
• Able to observe the simulation of circuit.
Program Education Objective(s) (PEO) Satisfied: 2, 3
• To enable student to analyse solve electronics engineering problem by applying basic principles of mathematics , sciences and engineering and also be able to use modern engineering techniques , skills and tools to fulfill social needs
• To enable to innovate, design and develop a variety of electronic and computer based components and system for applications including signal processing, communication, and computer network and control system.
Principle:
An simple RC circuit in which output taken across capacitor ‘c’. At low frequencies capacitor will occur maximum reactance hence acts as an open circuit. Resulting in transferring low frequency signal to the output at high frequencies capacitive reactance is negligible hence it act as an short transfer to the output.
Department of Electronics Engg., P.V.P.I.T., Budhgaon Circuit Diagram: Circuit arrangement:
The circuit arrangement of simple RC circuit as shown in fig. it consists of resister and capacitor. Output taken across capacitor as shown in fig. in these circuit Vr is voltage across resister and Vc is voltage across capacitor.
Theory:
A capacitor is a device for storing charge. The ability of a capacitor to hold a charge is measured by its capacitance C. For a capacitor, Q = CV, where Q is the charge on one of the capacitor plates, C is the capacitance of the capacitor, and V is the potential difference maintained across the capacitor plates. The unit of capacitance is the Farad (F), where one Farad equals one Coulomb per volt (1F = 1C/V).
If a capacitor is connected to a battery, it will cause a charge +Q to develop on one plate and a charge -Q to develop on the other. If the battery is removed from the circuit the capacitor is connected to a resistor, then the capacitor will discharge through the resistor. The voltage across the resistor is given by V = IR, where I is the current through the resistor at a given time, and R is the resistance of the resistor. Since V = Q/C, = we can also write
I = V/R = Q/RC
As the capacitor discharges, Q becomes smaller, and I also become smaller. The current at any time t is given by:
I = I0e-t/RC = I0e-t/τ
Where I0 = initial value of the current, ti = time elapsed in seconds since the discharging began τ = RC = capacitive time constant for the RC circuit, and e = 2.71828... .
AC Sweep:
In simple RC circuit we can apply AC sweep. For Ac sweep analysis is nothing but it is going to calculate to frequency response of the circuit. over range of frequencies the frequency response is nothing but the magnitude Vs frequency and phase Vs frequency. If
Department of Electronics Engg., P.V.P.I.T., Budhgaon
-20 and the slope of magnitude block is -20db/dc there are different type of sweep analysis. We have to consider following certain parameter in the frequency sweep. i.e. starting frequency and ending frequency. We have to specify the scale both linear, octave and decade.
• Linear sweep :
The frequency is sweep linearly from the starting frequency to the ending frequency with a step (number of step) the next frequency generated by a constant to a present value.
• Octave sweep :
The frequency is sweep logarithmically by octave the next frequency is generated by octave the next frequency is generated by multiplying a present value by a constant the larger than the unity octal sweep is use when frequency range is wide.
• Decade sweep :
The frequency is sweep logarithmically by decade. Decade is used if frequency range is widest.
How to do the AC Sweep Analysis using Proteus Simulation Tool? Introduction:
• AC sweep analysis is nothing but a frequency response analysis. • It is a linear analysis (small-signal analysis).
• It means it only considers the gain and phase response of the circuit; it does not limit voltages or currents.
• The non linear devices (like transistor amplifier) must be liberalized to run the analysis. To do this conversion, we have to
a. Compute the DC bias point for the circuit
b. Compute the complex impedance and/or transconductance values for each value for each device at this bias point.
c. Perform the linear circuit analysis at the frequencies of interest by using simplifying approximations.
• The Proteus tool will take care of all these activities.ie,
• The Proteus tool calculates the small-signal response of the circuit to a combination of inputs by transforming it around the bias point and treating it as a linear circuit.
Department of Electronics Engg., P.V.P.I.T., Budhgaon Working of a Simple RC Circuit:
When the toggle switch is in the open position shown in the diagram, the capacitor is not connected the Electromotive Force, emf, and, unless the capacitor was previously charged, there will be no charges stored in the capacitor (i.e., q = 0) and the potential difference between the plates of the capacitor will correspondingly be zero as well. If the switch is toggled so that it connects the capacitor to the Electromotive Force, charges will tend to accumulate on the plates of the capacitor, + on one plate, _ on the other. This will continue until the accumulated charge creates a potential difference (Vc) between the two plates that is numerically equal to the electromotive force. That
is, when: Vc = ,
Current flow through the connecting wires will cease (i.e., I = 0). When the switch is toggled to its alternate position, (i) the emf is bypassed, (ii) the two plates of the capacitor are connected, and (iii) the charges stored on the capacitor will tend to pass through the connecting wire to the opposite plate. In other words,
the charged capacitor will discharge.
There are 2 important things to remember about the electrical properties of R-C circuits:
1. When the capacitor (C) is fully charged, the following relationship holds:
q = C Equation 1a
Where q is the total amount of charge stored by the capacitor, C is the capacitance of the capacitor, and is the electromotive force that is actually charging the capacitor. Note that q = 0 when the capacitor is discharged. Also note that the equation may be rearranged thus:
q/C = = Vc Equation 1b
Meaning that placing excess + on one plate of the capacitor and excess – on the other plate will generate a potential difference between the plates.
2. Because of the presence of a resistance (R) in the circuit, current flow through the circuit is slowed. As a result, changing the amount of charge stored on the plates of the capacitor requires time. For example, if you were to start with a completely
Department of Electronics Engg., P.V.P.I.T., Budhgaon
qt = C(1 e-t/RC) Equation 2a
And if C = 1, = 10 and R = 1, the graph of qt vs. time would look like this:
Simple RC Circuit using AC sweep circuit using proteus.
Component:
Name Components Used Description Number of
components required
RES RC05 Resistor 2
CAP CAP Capacitor 2
Department of Electronics Engg., P.V.P.I.T., Budhgaon Procedure using Proteus:
• From main page of Proteus, click on ‗P‘ to click device from library.
• In pick device, insert the component which has to be selected & click on ‗OK‘. • Place the all components on the Proteus screen.
• Right click and select edit properties & select the proper value. • Add voltage probe at input and output of circuit.
• Select the graph mode then add trace in graph window. • Right click & select add traces (input & output trace). • Right click & activate simulation graph
• Observe the input & output waveforms.