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To do this I will use a very common Operational Amplifier (or Op Amp for short) the UA741CD. The main purpose of an inverting amplifier circuit is to take an input signal and increase it by the gain value that you have chosen as well as to shift the signal by 180 degrees with respect to the input signal. Working of an Operational Amplifier: Here we used an operational amplifier of LM358. Usually a non-inverting input has to be given to a biasing and the inverting input is the real amplifier; connected this to a feedback of 60k resister from output to the input.
This instructable will show you step by step how to build an inverting amplifier circuit. To do this I will use a very common Operational Amplifier (or Op Amp for short) the UA741CD. The main purpose of an inverting amplifier circuit is to take an input signal and increase it by the gain value that you have chosen as well as to shift the signal by 180 degrees with respect to the input signal.
This circuit takes about 10-15 minutes to build and test and it requires a beginner level experience to build this circuit. The inverting and non-inverting amplifier circuits are the basis for a wide variety of circuit and they are fun to build. Before building your inverting circuit you must first decide on the value of the gain that you wish to amplify your input signal. Since the equation for the gain of this circuit is very simple you can obtain your desired gain value by setting values for Rf and Rin. There are a variety of materials that can be used to create an inverting amplifier but these are the ones that you will use for the experiment:Materials:. 1x 100,000 ohm resistor (to be Rf).
1x 10,000 ohm resistor (to be Rin). 1x UA741CD op amp.
1x wire. 1x breadboard. 5x red connector cords. 4x black connector cordsEquipment:. 1x Tetratonix AFG3012B Function Generator.
1x Agilent E3631A Power Supply. 1x Agilent InfiniiVision DSO-X 2024A OscilloscopeNote: The Equipment pictures will be shown with their corresponding steps. Tip: Use the beveled edge of the op amp as the top. Place UA741CD op amp in the middle of the breadboard so that it has its pins inserted on both halves of the breadboard. Insert wire from the third pin (+) of the op amp to the ground terminal of the breadboard. Insert Rin (10,000 ohm resistor) from the second pin (-) of the op amp to an arbitrary point on the breadboard that is not connected to anything. Connect one end of Rf (100,000 ohm resistor) to the second pin (-) of the op amp with the other end connected to the sixth pin (output) of the op amp.Caution: Make sure none of the pins on the op amp are bent or it could be damaged when an input signal is applied.
With the input signal established you now need to bias your op amp so that it will not be overloaded. The best piece of equipment to do this is the Agilent E3631A Power Supply. Using the power supply you can set the biasing voltages to be what you want but for this experiment chose them to be +15V and -15V. The biasing will restrict the output signal from going above them.
With the power supply set up you can now connect it to the circuit.Caution: Do not turn on the output of the power supply until you are at the end of the instructions and you are sure you have everything hooked up correctly or you could burn out your op amp. Connect the +25V port of the power supply with a red cord to the seventh pin (+V) of the op amp. Connect the -25V port of the power supply with a red cord to the fourth pin (-V) of the op amp. Connect the COM port of the power supply with a black cord to the ground strp of the breadboard. Now that the circuit is built you will add an input signal to the circuit for it to amplify and invert and you will use the Tetratonix AFG3012B Function Generator to do so.
The input signal that you will establish for this experiment is a 1V peak to peak Sine wave with a 1000Hz frequency. With the new input signal you will connect the function generator to the breadboard.Caution: Do not turn on the output of the function generator until you are at the end of the instructions and you are sure you have everything hooked up correctly or you could burn out your op amp.
Connect the positive cord (red) from the function generator into the arbitrary pin that was established for the end of resistor Rin. Connect the ground cord (black) from the function generator to the ground terminal of the breadboard. With all the input signal and bias voltages hooked up to the circuit the last thing to connect are the cord to measure your output signal. The piece of equipment you will use to do this is the Agilent InfiniiVision DSO-X 2024A Oscilloscope.
You will also be hooking the function generator up to the oscilloscope so that you can view the input and output signals at the same time. Repeat Step 4 with the connections being from the oscilloscope instead of the function generator. Connect the red output cord from the oscilloscope to the sixth pin (output) of the op amp. Connect the black output cord from the oscilloscope to the output strip of the breadboard. Now that everything is connected to your circuit and that it is correct you can turn on your input signal and your bias voltages. Once this is done hit the auto scale button on the oscilloscope and view your results. Notice that the amplitude of the output signal (green wave) is about ten times that of the input signal (yellow wave) and that it is the inverse wave of the input.
Congratulations you have just built an inverting amplifier circuit and can now go on to building bigger and more complicated circuits.
Main article:This article illustrates some typical operational amplifier applications. A non-ideal operational amplifier's equivalent circuit has a finite input impedance, a non-zero output impedance, and a finite gain.
A real op-amp has a number of non-ideal features as shown in the diagram, but here a simplified schematic notation is used, many details such as device selection and power supply connections are not shown. Operational amplifiers are optimised for use with negative feedback, and this article discusses only negative-feedback applications. When positive feedback is required, a is usually more appropriate.
See for further information. Contents.Practical considerations Operational amplifiers parameter requirements In order for a particular device to be used in an application, it must satisfy certain requirements. The operational amplifier must. have large open-loop signal gain (voltage gain of 200,000 is obtained in early integrated circuit exemplars), and. have input impedance large with respect to values present in the feedback network.With these requirements satisfied, the op-amp is considered, and one can use the method of to quickly and intuitively grasp the 'behavior' of any of the op-amp circuits below.Component specification Resistors used in practical solid-state op-amp circuits are typically in the kΩ range. Resistors much greater than 1 MΩ cause excessive and make the circuit operation susceptible to significant errors due to bias or leakage currents.Input bias currents and input offset Practical operational amplifiers draw a small current from each of their inputs due to bias requirements (in the case of bipolar junction transistor-based inputs) or leakage (in the case of MOSFET-based inputs).These currents flow through the resistances connected to the inputs and produce small voltage drops across those resistances. Appropriate design of the feedback network can alleviate problems associated with input bias currents and common-mode gain, as explained below.
The heuristic rule is to ensure that the impedance 'looking out' of each input terminal is identical.To the extent that the input bias currents do not match, there will be an effective present, which can lead to problems in circuit performance. Many commercial op-amp offerings provide a method for tuning the operational amplifier to balance the inputs (e.g., 'offset null' or 'balance' pins that can interact with an external voltage source attached to a potentiometer).
Alternatively, a tunable external voltage can be added to one of the inputs in order to balance out the offset effect. Main article:Operational amplifiers can be used in construction of, providing high-pass, low-pass, band-pass, reject and delay functions. The high input impedance and gain of an op-amp allow straightforward calculation of element values, allowing accurate implementation of any desired filter topology with little concern for the loading effects of stages in the filter or of subsequent stages. However, the frequencies at which active filters can be implemented is limited; when the behavior of the amplifiers departs significantly from the ideal behavior assumed in elementary design of the filters, filter performance is degraded.Comparator. Main article:An operational amplifier can, if necessary, be forced to act as a comparator. The smallest difference between the input voltages will be amplified enormously, causing the output to swing to nearly the supply voltage. However, it is usually better to use a dedicated comparator for this purpose, as its output has a higher slew rate and can reach either power supply rail.
Some op-amps have clamping diodes on the input that prevent use as a comparator. Integration and differentiation Inverting integrator. Main article:Simulates an (i.e., provides without the use of a possibly costly inductor). The circuit exploits the fact that the current flowing through a capacitor behaves through time as the voltage across an inductor. The capacitor used in this circuit is smaller than the inductor it simulates and its capacitance is less subject to changes in value due to environmental changes.This circuit is unsuitable for applications relying on the property of an inductor as this will be limited in a gyrator circuit to the voltage supplies of the op-amp.
Main article:The voltage drop V F across the forward biased diode in the circuit of a passive rectifier is undesired. In this active version, the problem is solved by connecting the diode in the negative feedback loop. The op-amp compares the output voltage across the load with the input voltage and increases its own output voltage with the value of V F. As a result, the voltage drop V F is compensated and the circuit behaves very nearly as an ideal ( super) with V F = 0 V.The circuit has speed limitations at high frequency because of the slow negative feedback and due to the low slew rate of many non-ideal op-amps.