741ce OP amp help..

Thread Starter

chunkmartinez

Joined Jan 6, 2007
180
Some of you may know, I'm working on a clipping detector circuit...Well I haven't used OP amps before in the real world and I cannot ge a simple expiriment to work.

Heres what I tried:

9 volt or 7 AAs in series for the power supply, a non split power supply just 0v GND and the pos of the batt...

I tried Grounding the inputs in common mode from the power supply GND so that I can see the offset..I get the full saturated output though. If I attatch a negative feedback lead I believe I get .40ma but a potentiometer dosn't change the value when I turn it and I have it connected to the null pins. So is it possible that without a negative feedback lead I will get saturation at the output while the inputs are grounded? And why dosn't the pot change the offset value?
 

Papabravo

Joined Feb 24, 2006
21,226
RTFDS!! The 45-year old, totally obsolete 741, needs dual supplies or a single supply with a virtual GND at Vcc/2

Get a modern part that can run with a single supply and stop wasting your time.
 

Audioguru

Joined Dec 20, 2007
11,248
I would also like to say that to nOObs but what does it mean?

I agree that only teachers and school kids use the obsolete 741 opamp today.

Look at the MC34071 single, MC34072 dual and MC34074 quad opamps. They have inputs that work at ground and have an output that goes almost down to ground with a single positive supply. They go very well as high as 100kHz.
 

Papabravo

Joined Feb 24, 2006
21,226
I would also like to say that to nOObs but what does it mean?

I agree that only teachers and school kids use the obsolete 741 opamp today.

Look at the MC34071 single, MC34072 dual and MC34074 quad opamps. They have inputs that work at ground and have an output that goes almost down to ground with a single positive supply. They go very well as high as 100kHz.
It means "Read the datasheet, before using the part". No matter what you think it says and no matter what the textbooks tell you the only authoritative source is the datasheet. For this part I'm not even sure there is a manufacturer that publishes a current one. That, in and of itself, is a huge clue that you need to find a more current part lest everything you learn be rendered useless.
 

thatoneguy

Joined Feb 19, 2009
6,359
MC30472 Dual Op Amp Datasheet

That is a decent single rail Dual Op Amp that outclasses the 741 in every aspect. The biggest differences are that it is has 2 op amps in one package, and runs from a single supply. The slew rate is also higher so that it can work with higher audio frequencies than the 741 can.
 

Audioguru

Joined Dec 20, 2007
11,248
Lazy teachers who do not teach and lazy students who do not learn should be shot, set on fire then drawn and quartered.

Many students today are not interested in ANYTHING so they select a career at random. They do poorly in the career. Like many teachers.
 

SgtWookie

Joined Jul 17, 2007
22,230
The TL082 also requires a dual power supply; it can't get within about 1.5v of +V nor within about 3v of -V. As has already been said, you should learn how to read the datasheet.

It's not easy at first, but the more you read and try to understand them, the more sense they will make.
 

Thread Starter

chunkmartinez

Joined Jan 6, 2007
180
Well I'm going to use a simple resistor dual power supply first When I recieve my rail splitter I will use it. I'm going to use a high resistance load to try and insure balance..
 
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