μA741C General-purpose operational amplifier

Thread Starter

alexandko

Joined Jan 13, 2021
3
Hello, it's the end of the semester and one of my things to do is to explain:
How does the μA741C amplifier work, what are its specs?
Where is it used?
What's the function of the offset-voltage null capability in it?

The problem is that the teacher didn't say a thing about it maybe because he gave the assignments at the beginning of the year and because of covid he had to shorten the material or maybe he just didn't want to talk about it at all, yesterday he sent me an "explanation file" from a market store like texasinstruments or something, which answered 1 question, that I didn't put in this thread. I searched in forums and in youtube, but I couldn't find anything particular. I'd be really thankful if somebody helped. I'll attach the amplifier's scheme.

Screenshot_11.png
 

crutschow

Joined Mar 14, 2008
27,210
Look up the data sheet for the 741 op amp, and look up the definition of operational amplifier.
After you've read those come back here with your questions.
 

MrAl

Joined Jun 17, 2014
8,246
Hello, it's the end of the semester and one of my things to do is to explain:
How does the μA741C amplifier work, what are its specs?
Where is it used?
What's the function of the offset-voltage null capability in it?

The problem is that the teacher didn't say a thing about it maybe because he gave the assignments at the beginning of the year and because of covid he had to shorten the material or maybe he just didn't want to talk about it at all, yesterday he sent me an "explanation file" from a market store like texasinstruments or something, which answered 1 question, that I didn't put in this thread. I searched in forums and in youtube, but I couldn't find anything particular. I'd be really thankful if somebody helped. I'll attach the amplifier's scheme.

View attachment 227668




Hello,

Well if you really want to know how the 741 works you would have to study the internal diagram. However i think that might be beyond what you actually want to do.

You can look up the specs that's not hard. The internet is wonderful for this. When i was just starting out we had physical books and books and books to look up specs for various parts. Now we have the internet and all you have to do is type the part number into a search engine and you will get lots of hits.

As to the question of what the 'null' does, you would have to read up on what an offset null for an op amp is and why it is useful. There isnt much to it really.

You could at the same time look up various applications that the 741 is used in and you will find there are a lot. There are limitations to this op amp that sometimes get in the way but you will find that out when you look up the specs on the internet. You will have a lot to read but you should find it interesting.
 

Papabravo

Joined Feb 24, 2006
16,132
Hello, it's the end of the semester and one of my things to do is to explain:
How does the μA741C amplifier work, what are its specs?
Where is it used?
What's the function of the offset-voltage null capability in it?

The problem is that the teacher didn't say a thing about it maybe because he gave the assignments at the beginning of the year and because of covid he had to shorten the material or maybe he just didn't want to talk about it at all, yesterday he sent me an "explanation file" from a market store like texasinstruments or something, which answered 1 question, that I didn't put in this thread. I searched in forums and in youtube, but I couldn't find anything particular. I'd be really thankful if somebody helped. I'll attach the amplifier's scheme.

View attachment 227668
If you are paying for education and getting less than you expect you need to take that up with the provider. As others have noted you have many resources available to you that we never did. Some combination of books internet articles or even You-tube videos should at least set you on the correct path. I will give you a couple of hints:
  1. No current flows into either of the amplifier inputs. They are very high impedance.
  2. At any node in the circuit, the sum of the currents must be zero.
For example if U1 is the voltage at the junction of R1 and R1, the currents are (U0 - U1)/R2 , and (U1 - Ug-)/R1, and 0 which goes to the amplifiers inverting input.
 

Thread Starter

alexandko

Joined Jan 13, 2021
3
To be honest I don't know if you'll get a notification for this, but you really helped me out, I'm more than 3/4 done with the assignment. The main challenge is to explain everything in Bulgarian afterwards, that's why I need someone to explain it to me correctly. I have 1 new question, which is: what is the transmission characteristic (transmission curve) called for the file I've attached.

Screenshot_12.png

The question "how do I properly explain how does the μA741C work" remains
 

dl324

Joined Mar 30, 2015
12,871
I searched in forums and in youtube, but I couldn't find anything particular.
Your instructor probably intended for you to look for the information. It's widely available on the internet if you know where to look for it.

Hint - look for a Signetics Analog Handbook from the late 70's (yes, that's how long the information has been readily available).
 

Thread Starter

alexandko

Joined Jan 13, 2021
3
Update: I answered the question about the characteristics and how is it called. Now I need a source, where I can get something like an algorithm of how the amplifier works. I'll check out everything new you've suggested.
 

ericgibbs

Joined Jan 29, 2010
12,908
I agree that the "teacher" is absolutely useless. The 53 years old 741 opamp is also useless and should be buried.
hi agu,
Where does it say in this Thread that the "teacher" is absolutely useless, that you are agreeing with.??

Its most likely not the teacher who is at at fault, they usually have to teach a predetermined curriculum, using the material resources allocated to the course.

E
 

LvW

Joined Jun 13, 2013
1,247
I agree that the "teacher" is absolutely useless. The 53 years old 741 opamp is also useless and should be buried.
You should not forget that the task is to EXPLAIN something. And it is not too bad - as a first example - to choose an amplifier topology that is relatively simple to understand.
More than that, there are hundreds (if not thousands) articles and application hints based on the 741 reference.
In case you want to develop a new electronic circuit - you are, of course, free to select another device.
 

crutschow

Joined Mar 14, 2008
27,210
The question "how do I properly explain how does the μA741C work" remains
That question is very vague.
At what level of explanation are you needing.?
Certainly if you want a transistor-by-transistor explanation of how it works internally, that's beyond the scope of this forum.

The 741 is an op amp.
Do you know how op amps work?
If not, then you need to study that.
 

Audioguru again

Joined Oct 21, 2019
3,186
I said that the teacher is useless because the semester has ended and the teacher did not teach what is needed for the assignment. Post #7 said, " Your instructor probably intended for you to look for the information" instead of teaching it. I agree with that.
 

MrAl

Joined Jun 17, 2014
8,246
Old teachers use old 741 opamps. I bet most old teachers know nothing about modern audio opamps, Cmos opamps and rail-to-rail opamps.
Certainly would not be the first time i heard strange stories about so called 'professors'. They got their degrees at Walmart University. :)
 

LvW

Joined Jun 13, 2013
1,247
Certainly would not be the first time i heard strange stories about so called 'professors'. They got their degrees at Walmart University. :)
I am 75 years old - I was teaching analog electronics for 25 years at a "University of applied Sciences". I have treated, for example, analog filter solutions based on opamps, current feedback amplifiers, current conveyors, OTAs as well as discrete transistors.
Satisfied?

Quote: "Your instructor probably intended for you to look for the information" instead of teaching it."
It is quite a challenge to find a suitable balance between "teaching" (by a lecturer) and "self-teaching" (by students). Don`t overlook the importance of the latter
 
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