LM741 OP-AMP Basics With Example Circuits

LM741 is a very common general-purpose operational amplifier IC used in many kinds of circuits; you might have already used one before. 

However, this article will provide more information about the LM741 OP-AMP, its features, typical configurations, and some example circuits.

The LM741, LM741A, and LM741C—and their application-specific relative, µA741 or HA1741—are in the 741 series of operational amplifiers. They offer great performance compared to other OP-AMP ICs. Furthermore, they come with overload protection, which makes them easier and safer to use.

The LM741 Chip

It is a relatively advanced integrated circuit packed in a plastic eight-pin DIP-8 package. The LM741 has also been around for some time now but remains popular. 

Plus, it also has an affordable price comparable to a transistor, which adds to its popularity.

General Features

The basic feature of an amplifier is that it takes an AC or DC input and amplifies the signal to a higher level at the output. However, the LM741 OP-AMP also has the following basic features:

• Overload protection—protects both the input and the output of the chip.
• Latch-up prevention—allows the chip to operate smoothly without having to power it off and on.
• Open- and closed-loop modes—LM741 can operate in open-loop configuration for higher gain or with a feedback network.

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Specifications of 741 OP-AMP

• Supply voltage range: ±5V to ±18V
• Input offset voltage: 2mV to 6mV
• Input Impedance: 300KΩ to 2MΩ
• Power consumption: 50mW to 85mW
• Supply current: 1.7mA to 2.8mA
• Power Dissipation: 0.5W
• Differential input voltage:±30V
• Max Input voltage:±15V
  (should not exceed the power supply voltage)
• Output short circuit time: none
• Operating temperature: 0 to 70°C
• Voltage Gain: 20,000 to 200,000
• Input offset voltage: 2mV to 6mV
• Input Impedance: 300KΩ to 2MΩ
• Bandwidth: 500KHz to 1.5MHz
• Slew rate: 0.5V per uS

Note that each of the variants of 741 chips, LM741, LM741A, LM741C, or even uA741, has different minor specifications. Therefore, if you are planning to use one in your project, please refer to the specific datasheet here.

Pinouts

As mentioned, the LM741 has eight pins; however, only five of those pins are typically used: positive and negative supply, non- and inverting input, and one output. This is reflected in its schematic symbol as shown below.

I think you want to use 741 op-amps. It is so easy if you know about its legs or 741 pinouts. Although there are only eight legs, each leg is important.

• Pin 1—Offset null
• Pin 2—Inverting input
• Pin 3—Non-Inverting input
• Pin 4—Negative Supply
• Pin 5—No connection
• Pin 6—Output
• Pin 7—Positive Supply
• Pin 8—Offset null

The LM741 in a schematic drawing is most often this triangular OP-AMP symbol. It is simpler than the full DIP-8 depiction while still containing most of the pins we usually use, and it is laid out in an easy-to-understand way.

The Power Supply

An OP-AMP usually requires a dual-polarity power supply to operate; for the LM741, it is recommended for a 4.5V to 18V power supply. For long-term uses, you should use a proper dual-polarity power supply such as this one. [power supply plug]

However, using two 9V batteries together as shown below also works as a temporary solution while experimenting. But in saying that, the LM741 has a very low power consumption, so using battery power long-term is not much of an issue.

Then simply connect the power supply to the OP-AMP as shown below, +9V to pin 7 and -9V to pin 4. The difference between the positive and negative power also determines the range of the output, which we will talk more about later.

Type of OP-AMP Configurations

There are many ways to configure an amplifier with the LM741. We will only cover the few types we often use, and they might also be useful to you.

However, if you have any amplifiers you would like to learn more about, then feel free to leave a comment below, and we will try our best to cover them. Anyhow, here are three of the common LM741 amplifier configurations.

Differential Amplifier

Let’s start with the differential amplifier since it is a base for many other amplifiers. As the name may suggest, it amplifies the voltage difference between the two inputs by some gain.

The graph below shows the relation between the inputs and output of a differential amplifier.

If both inputs have the same voltage, meaning there is no voltage difference, the output will be 0V. However, the output voltage will be HIGH when the positive input receives a higher voltage than the negative. 

This is also true the other way around, the output will be LOW when the negative input has a higher voltage than the positive one. In summary: higher positive input means positive output; higher negative input means negative output, as shown here:

The graph shows that the voltage difference required for the output to swing from lowest to highest is 200μV. If you recall, we are using two 9V batteries as a power supply; this means that the output voltage swing range is 18V, with a minimum of -9V and a maximum of 9V.

In this case, the OP-AMP operates in a linear range, which means that a small change in input influences a bigger change in output. So, if the positive input is within 200μV higher than the negative input, the output will be in a HIGH state and have a positive voltage proportional to the voltage difference between the two inputs.

However, suppose the negative input is within 200μV higher than the positive input. In that case, the output will be in a LOW state and have a negative voltage proportional to the voltage difference between the two inputs.

Inverting Amplifier

An inverting amplifier uses a similar idea to the differential amplifier but without the input voltage difference parts. The positive input, or the non-inverting pin, connects to the ground and acts as a reference point for the negative input.

When voltage is applied to the negative input, the output changes inverting and proportionally to it.

Non-inverting Amplifier

A non-inverting amplifier, on the other hand, works by just amplifying the input signal proportional to the gain without inverting it. In a non-inverting configuration, the negative input, or the inverting pin, is connected to the ground instead.

Using a Single Power Supply

The OP-AMP—in this case, the LM741—can also operate from a single power supply, as shown below, reducing circuit complexity by eliminating the need for a dual-polarity power supply.

However, because of the lack of a negative rail, the point at which there is no difference in input voltage shifts up from 0V to the ½ point of the supply voltage instead. The swing range remains the same at 200μV. Therefore, depending on the situation, using a single power supply may not be feasible.

Recommended: How to use op-amp in the power supply

Thanks to the Wise Cr: Learn op-amp working as power supply on the Talking Electronics No.9 page 25 to 29

10 Example 741 circuits

Throughout the years, I have collected many small LM741 amplifier circuits, both for use in actual applications and as inspiration for future projects. 

The list I compiled below includes the majority of the circuit types I frequently see, and, despite their age, many of them are still applicable today.

Inverting Amplifier Circuit Using LM741

This circuit is a practical implementation of the inverting amplifier we mentioned earlier. Its core function remains the same; the output is amplified inversely to the input. 

The two components are resistors, the resistance of which controls the gain of the amplifier. We can see their relation clearly through the following formula:

Vout = -Vin(R2/R1)

Non-Inverting Amplifier Circuit Using LM741

Similar to the inverting amplifier circuit above, this is a functional version of the non-inverting amplifier. It amplifies the input to the output but does not invert the signal.

The two resistors work similarly to the one in the inverting amplifier. However, as the circuit does not invert the input, we use a different formula to calculate the output:

Vout = Vin(1+ R2/R1)

Basic Summing Amplifier Circuit Using LM741

The summing amplifier is another handy amplifier circuit. As the name may suggest, it will output the sum of multiple inputs. But since this circuit is in an inverting amplifier mode, it will output the negative of that sum.

This means we could combine multiple voltage inputs. However, the example circuit here has only two inputs, and its output is as follows:

Vout = -R4 ((Vin1/R1) + (Vin2/R2))

When R1 = R2, but not R4:

Vout = – R4/R1 (Vin1+Vin2)

Whereas when R1 = R2 = R4:

Vout = – Vin1 + Vin2

An audio mixer, for example, is an excellent application for a summing amplifier, which sums multiple sounds from different channels before sending the signal to another amplifier circuit.

You can read about Summing Amplifier HERE.

The Clipping Amplifier Circuit

When an amplifier is overdrive output waveform of voltage and current distortion. it is limit size value.

This is the Clipping Amplifier Circuit using LM741(popular op-amp IC. It is a basic clipping amplifier. If the input is sine wave to distorted square wave type waveform.

Vout = -Vin(R2/R1)

But the Vout not up to Vz+0.7V

The D1 and D2 are a Zener diode. If we use 6V values, have already the output voltage not exceed +/- 6.7V.

Read also: Learn ON-OFF Light and Temperature Controller using 741 op-amp

Vout = -Vin(R2/R1) But the Vout not up to Vz+0.7V

D1 and D2 are Zener Diode if use 6V values have already the pressure output not exceed +/- 6.7V.

Basic Integrator using LM741

This is the basic integrator circuit used IC op-amp 741 is an important part. The following by ranges of input into the R1. It is Element Input and the C1 is the feedback element.

This circuit has a different form of differentiator circuit. The relationship of the incoming signal frequency. It has the effect of changes in voltage output as well.

So increased in parallel with R2 to control C1 (Low-Frequency Resistor).

When the frequency changes.When the frequency changes, and increased leg R3 Non-Inverting. To reduce the voltage Voi.

Read next: Universal Preamplifiers using | NE5532 | 741 | LM382

Single Polarity Supply circuit using LM741

This is a simple Single polarity (negative to positive polarity) power supply circuit.

For education, the work of a series op-amp. Since we use the input pin is a pin non-inverting. It is an important condition.

We try to come to see this circuit use op-amp IC LM741, be usable easily.

And, It can change R1, R2 for fix the expansion ratio has of the circuit with.

See the detail in the circuit.

The input power must be negative only. As a result, the output voltage.

However, if the input is positive, it will not delete the output.

Because we used the power supply terminal positive and negative only.Or 4 pin connection with the ground.

This circuit may be adapted to the negative circuit. Or to converter a negative voltage to positive voltage.

Unity Gain Follower Or Buffer Circuit Using LM741

The buffer op-amp circuit. We use it for coupling two circuits together. Or the Unity Gain Follower Voltage Follower is used to transfer or copy a voltage from a first circuit (Vin) to a second circuit (V out).

The input has a high impedance, and the output is low impedance. such as the differential family of the IC or transistor that’s not good impedance matching.

The op-amp IC objects have the output low impedance and input high impedance.

When connected to other circuits, so there is no effect. The gain is equal to 1 always. Does not to change any signal.

Vin = Vout

This circuit is an example of a buffer op-amp circuit, use IC Number LM741 performs this function very well, does not require any additional equipment.

We can use signals with any format, but the frequency response up to 1Mhz.

And limit the maximum voltage level power supply circuit is about 18V. This circuit voltage power supply is +/- 5V to 18V.

Simple Level Voltage Detector Circuit

Simple Low Pass Active Filter Circuit

When you want to filter low frequency gives can change only. I thinks the Low Pass Active Filter circuit help you. Because of it uses IC LM741,then usable easy follow circuit image. We can fix the frequency is cut off get, by equipment value R1=R2 = R , and C1=C2=C When fix give 50Hz frequencies low only that can change. Values Show be valuable about 0dB = 50Hz , -3dB = 250Hz , -50dB = 10kHz

Then will see tall frequency 50Hz more cut give until less is finished. This circuit should use dual power supply positive,negative,GND +/- 5V to 18V in order to get a signal that is appropriate most.

Here are a few related posts you might want to read next:

• Automatic Night light circuit using LDR and IC-741
• Active bass booster circuit using 741
• Automatic Op-amp night light circuit using 741

 

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