Op Amp Gain

S

smudge

New Member

• Apr 7, 2004

• #1

Hi

I am new to Op Amps so could anybody help me with a question regarding this please.

I need to create a circuit wherethe output is ten times the difference between its two input signals. I think this could be realised using just two operational amplifiers and five resistors.

could anybody help please??? :lol:

 

Phasor

Member

• Apr 7, 2004

• #2

Only one opamp is required, and four resistors.

Like so:

 

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S

smudge

New Member

• Apr 7, 2004

• #3

Sorry I forgot to mention the equation I would like to base my circuit around.

Vo=10(V2-V1)

Would a second op amp be required to get rid of the -

 

Phasor

Member

• Apr 7, 2004

• #4

Yes, you could use an inverting amplifier, with a gain of -1, on the output of the above circuit.

Or you could just swap the inputs.

 

Roff

Well-Known Member

• Apr 7, 2004

• #5

The circuit Phasor posted has the gain you want. No inversion is required.

 

S

smudge

New Member

• Apr 7, 2004

• #6

I have used the search engines to find information regarding OP AMPS and indeed the example given above is used in many instances. However, the question I have requires me to find any information I can to obtain the same results using 2 Op Amps & 5 Resistors. I would also like to find any relevant equations to find the resistor values. This is proving rather difficult, I have been on many sites!!!

 

Roff

Well-Known Member

• Apr 7, 2004

• #7

See National Semiconductor's Application Note 31, pages 15 and 16.