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# Op amps

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#### axro

##### New Member
I've been trying to get a grip on op amps and I can't find anything online that's very helpful. Can some one give me a good explanation, or point me to a website that has a good explanation(with examples). I don't really want to know the math right, know just what they are good for and how to use them.

Also to use an op amp do you have to have a negative power supply? Like just a standard wall wart won't work?

wiki has a great article on op amps

I've looked at that. While it's very in depth thats not really what I'm looking for. What I really want is a something simple for right away. With some real life examples that I can relate to.

Google has plenty, try "OpAmp circuits" got plenty of hits.

Some opamp circuits use dual-polarity supply voltages so that the input is biased at half-way which is 0V then the output is also half-way at 0V and can swing the maximum positive or negative.

Any opamp can use a single supply voltage if its input is biased at half the supply voltage and its input, output and feedback 0V connection are capacitor-coupled.
Then its output is also at half the supply voltage and can swing the maximum amount in a positive or a negative direction.

Thanks audioguru.

I'm not really looking for circuits. More something like:

An opamp does ____.
We connect this to hear because ____.
If you do this then _____.

A tutorial of sorts I guess.

What would be a good op amp to purcase just to do some testing and to get familiar with them?

I plan on making an order on Goldmine Electronics, so I would like to get one that is available on there.

Quick Tutorial

An opamp does
Amplifies a voltage signal.
We connect this to hear because
A signal or voltage to the positive (Non-inverting Amp) or negative (Inverting Amp) input. The other input is connected to a reference or to a feedback element in the circuit..
If you do this then
When the positve input is increased to a value larger than the negative input the output goes higher and vise versa.

The opamp is used in many configurations so a more in depth discussion would take a lot more. For simple experiments and testing a LM741 would be a good choice.

This one is good.

Renato

The LF351 was invented by National Semiconductor a long time ago. 11 years ago they stopped making it but ST Micro still make it as a replacement.

You should use an opamp that is still made by the company who invented it so that it will continue to be available as your favourite.

The TL081 will directly replace the LF351 in most applications.

See chapter 8 here

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