# design with an op amp

Discussion in 'Homework Help' started by Kin Moon Kong, Jun 21, 2015.

1. ### Kin Moon Kong Thread Starter New Member

Jun 21, 2015
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I had a school assignment to submit i understand the two rule of an ideal and practical use of op-am. The properties of non-inverting, inverting and summing amplifier. but i am struggling with my assignment, which require your help. I was given ten option to choose i pick option 6. the question is: Given that the pressure sensor produces an output voltage (Vs :sensor output voltage) according to the equation Vs = (Px0.131)+1.683. This equation can be expressed in terms of pressure (P) versus sensor voltage (vs)i.e P=(vs – 1.683)/0.131 You are to design the amplifier circuit for this sensor using any combination of inverting amplifier, non inverting amplifier, summing amplifier together with a 1V reference voltage source. The two input signals of this circuit are sensor voltage (Vs) and an 1V reference source (Vref) and the circuit should produce an output voltage (Vo) indicating the pressure (PSI) according to the equation Vo = P(PSI) i.e When P=0PSI, Vo=OV When P=10PSI, Vo=10V When P= -10PSI, Vo= -1OV

2. ### WBahn Moderator

Mar 31, 2012
17,715
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Okay. So what is your question?

You say you picked option 6. Are we supposed to be mind readers and simply know what option 6 is?

Here's a concept: YOU need to show YOUR best attempt to answer YOUR homework.

Jun 21, 2015
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4. ### ericgibbs Senior Member

Jan 29, 2010
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Do you mean you had to choose a question from a list of 10 questions and you chose question 6 from the list.?

Can we see your attempt at the answer?

5. ### Alec_t AAC Fanatic!

Sep 17, 2013
5,771
1,103
Hint: there are two things you need your opamp(s) to do:
1) scale a value,
2) sum two values.
Consider how you will configure the opamp(s) to achieve those functions.

Jun 21, 2015
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Jun 21, 2015
5
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thanks Alec

8. ### Kin Moon Kong Thread Starter New Member

Jun 21, 2015
5
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but how do I find the RF and other resistor values?

9. ### panic mode Senior Member

Oct 10, 2011
1,318
304
you draw some circuits, write equations and solve them.

10. ### atferrari AAC Fanatic!

Jan 6, 2004
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The thread's title is wrong. He is tasked to use an op amp (or many).

11. ### atferrari AAC Fanatic!

Jan 6, 2004
2,644
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Block diagram maybe? That would help to get a schematic I think.

12. ### panic mode Senior Member

Oct 10, 2011
1,318
304
most basic opamp circuits are just inverting and non-inverting amplifier (the only simpler one is voltage follower).
circuits are simple and once the gain is derived, it is easy to see which one is to be used.

13. ### Ricky Sum New Member

May 6, 2016
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Hi, do you have any reference for your this project.

14. ### Alec_t AAC Fanatic!

Sep 17, 2013
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I doubt the OP has any interest in this now, Ricky. The thread is nearly a year old!

15. ### Ricky Sum New Member

May 6, 2016
13
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Because I same one assignment quick similar to this. So I need some reference.

16. ### WBahn Moderator

Mar 31, 2012
17,715
4,788
What kind of reference are you looking for? A complete circuit that you can copy and turn in as your own?

thumb2 likes this.
17. ### Alec_t AAC Fanatic!

Sep 17, 2013
5,771
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See post #5. Where are your efforts so far?

May 20, 2015
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Help

19. ### dannyf Well-Known Member

Sep 13, 2015
1,768
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Just decompose your equation into templates for opamp modules.

Here, it is

Vout = k x (Vin - V0).

So it is a non inverting amplifier for k > 1 (solutions exist if k is less than 1).

You just need to rewrite it to match the templates.