An active amplifier or operational amplifier or op-amp is a high-gain direct coupled negative feedback amplifier. It is used in linear and non-linear operations. Currently manufactured in the form of integrated circuits. It is a type of integrated circuit. In this post, we will start with a basic operational amplifier IC and a 741 operational amplifier. Which is so basic that it is used first when teaching someone to the op-amp. So, hope we learn it with lots of fun and seriousness.
Operational Amplifier IC Introduction: uA741 Op-AMP
This is an operational amplifier IC. The total number of pins is 8. But here all 8 pins are not used for the same purpose. Hope we all know the pin identification of the IC. And those who don’t know can click here to see how to determine the PIN of the IC.
What is inside this 741 IC?
If we separate this IC and make it on a PCB then we can see in the circuit-
- 20 Transistors
- 11 Registers and
- There is 1 Ceramic Capacitor
Below you can see such a picture created by Adafruit Company-
Then you can understand how much this huge operational amplifier circuit has been reduced to a 741 IC shape. The actual size comparison of a 4-pin IC as you can see in the above picture compared with a coin.
uA-741 Operational Amplifier IC Pin Introduction:
Below are the various pin contacts of this IC-
PINs 2 and 3 of this operational amplifier IC we use for the input signal. That is, if we want to amplify any signal, then we have to input the signal on PINs 2 and 3.
Pin 2 is used as an (Inverting) pin and pin 3 is used as a (Non-Inverting) pin. That is, the IC manufacturing company has specified it this way.
PINs 1 and 5 are used for offset-null (Offset null). This eliminates any unwanted voltage at the output of the operational amplifier IC.
And PIN 8 is not connected to anything. It is only part of this DIL8 package.
The supply voltage of this IC is a minimum of 15 volts. But will it turn on by applying 15 volts directly? Of course not. So now the way?
Now come to the most important thing. That is generally we know that for the input power supply of any power amplifier IC we use the positive and ground pins of the supply. But it is very different with this IC. This means if we want to enable it for use then we have to bias it and use a split power supply as power supply.
Power Supply and Biasing of 741 IC:
Biasing is the process of applying an external voltage to an electronic device to operate it. In other words, the mechanism by which the variation between the output impedance or resistance and the input impedance or resistance in the transistor circuit of the electronic equipment is called biasing.
How to bias op-amp 741 IC?
For this, we will need 3 ends of 2 cell batteries or a split power supply ie plus-minus and ground. If it is a cell battery or a supply with 2 different outputs then the negative (-) end of one of the 2 power supplies and the positive (+) end of the other should be used as ground. The other 1 positive (+) end and one negative (-) end will go into the IC pins. And the aforementioned 741 op-amp IC has –
Positive (+) 15 volts, which is PIN 7, and Negative (-) 15 volts should be given as input with PIN 4. Only then can the IC be turned on.
Note here that in some special circuits the 741 IC can be driven by a normal power supply. In that case, its efficiency is also reduced significantly or the complexity of the circuit is increased if we want to use it at full efficiency.
The Basic Difference Between Op Amp IC Lm741 and uA741
The LM741 and UA741 both are DC-Coupled high gain electronic voltage amplifier IC. But the LM741 series Op-amp are general-purpose operational amplifier and the UA741 series Op-amp is a high-performance monolithic operational amplifier constructed on a single silicon chip.
The UA741 IC is a single package operational amplifier that can be used in a wide range of applications, especially by students as well as engineers.
Both are made of silicon and both can be used in general-purpose applications such as buffers, voltage followers, adders, amplifiers, comparators, etc.