Time domain study of a Linear System
Frequency domain study of a Linear System using a DDS Function Generator, an extra accessory
Op-amp simulated system for greater accuracy
Flexible system configuration u Full details of experiments included
Additional experiments possible


The most important performance aspect of a practical system is its response to known inputs.
The analysis of such systems therefore includes time and frequency domain studies, the former has direct relevance to most practical situations while the latter offers a relatively smoother experimentation with no sharp transients. Both these methods form part of any curriculum of control systems.
The setup offered is a variable configuration simulated system designed for the study of both open loop and closed loop systems.
Selection at block diagram level eliminates the need to bother about the details of electronic circuitry and its assembly. Thus time and efforts could be directed towards
understanding and experimenting with the basic aspects of linear control systems.
Schematic diagram of the simulator shown includes transfer functions of the form 1/s and 1/(sT+1), a calibrated variable gain K and an error detector.
These could be combined to form a variety of system configurations. The unity gain uncommitted amplifier can be used to ensure negative feedback for any combination. The time constants have been selected such that the system response may be observed conveniently on a CRO. This avoids the need to use an expensive and delicate X-Y recorder for the experiment. Built-in square wave and triangular wave generators provide test inputs to study both transient and steady state responses. Provision is also there to observe the effect of disturbances.
Frequency domain study can be performed using an external sine wave source. A DDS signal generator, Type 6600, offers a convenient and accurate phase measurement and is strongly recommended for this purpose.
An exhaustive literature is supplied with the unit to enable the students to understand and appreciate the intricacies and importance of time and frequency response studies of linear systems.
Correlation between the results of both the techniques is highlighted. The description includes mathematical analysis, procedure for experiments, typical results and suggestions for additional experimentation.


• Open loop step response of First Order type-0 system for various values of gain • Closed loop step response of First Order type0 system for various values of gain • Open loop step response of Second Order type-0 and type-1 systems
• Closed loop step response of Second Order type-0 and type-1 systems
• Steady-State errors for closed loop configuration through triangular wave input
• Response of third order system • Frequency response (Bode diagrams) of open and closed loop systems.
In each of the above, the experimental results obtained by measurements of the response curves can be compared with theoretical calculations
The number of experiments possible on the unit is not limited to those suggested above. Subject to the availability of time many more variations of the above are feasible

Features and Specifications
• Simulated first, second and third order system
of type-0 and type-1 (4 combinations)
• Calibrated variable gain amplifier
(Resolution 1 : 1000)
• Built-in signal sources: Square wave and Triangular
Frequency : 45-90Hz
Amplitude: 0-2.5V approximately
• Trigger output for perfectly steady display on CRO
• Uncommitted amplifier for phase adjustment
• Provision for disturbance inputs
• 220V±10%, 50Hz mains operation
• Complete in all respect, except a measuring CRO


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