# LM741 Integrator and Audio Amplifier circuits

Discussion in 'Audio' started by Integrator741, Nov 25, 2013.

1. ### Integrator741

125
4
Jun 16, 2013
Hello, I am trying to gain some theoretical knowledge about the operation of LM741 in "Integrator circuit" and "Audio amplifier circuit".

Circuit 1. Integrator:

Circuit 2. Audio Amplifier:

Now I understand what components do in the circuits. I know what components are in the 741, but what I don't understand how 741 works itself. What is happening inside that thing, when the circuit in ON?

I would be more than happy if somebody would offer me some reading material.

Thanks

2. ### BobK

7,673
1,684
Jan 5, 2010
An operational amplifier takes the difference in the voltage of it's two inputs (+ and -) and multiplies it by a very large number (like 100000) and then outputs that voltage.

All of the magic in using them comes from applying feedback from the output to the - input, which gives you great control of how much amplificiation, and of what frequencies.

Bob

3. ### Integrator741

125
4
Jun 16, 2013
okay so we use 741 in amplifier circuits because it gas huge gain and input/output always voltage.
But why do we use 741 (in my case LM741) in integrator circuit that generates triangle wave. What is the purpose of choosing 741 IC? To what specifications I should pay attention?

4. ### BobK

7,673
1,684
Jan 5, 2010
In an integrator, the op amp is used to charge a capacitor with a current that depends on the input voltage. The voltage on the capacitor then follows the integral of the input voltage over time.

Bob

5. ### duke37

5,297
739
Jan 9, 2011
A 741 is usually chosen because it has been around since the beginning of time and everyone knows it.

Op amps are not ideal so other op amps may be more suitable for:-
Power voltage range.
Inputs down to negative line
Very low input current
High frequency operation.
Multiple amps on one chip
Power capability
Low noise
Size
Others that I havn't thought of.

Note that C1, the integrating capacitor must be a bipolar capacitor not an electrolytic.

6. ### BobK

7,673
1,684
Jan 5, 2010
rail to rail outputs

Bob