Which resistors should I use to generate a gain of 15 on an inverting amplifier?

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Discussion Overview

The discussion revolves around selecting resistor values to achieve a gain of 15 in both inverting and non-inverting amplifier configurations. Participants explore the appropriate resistor combinations from a specified set of available values.

Discussion Character

  • Technical explanation, Debate/contested, Homework-related

Main Points Raised

  • One participant lists available resistor values and seeks guidance on achieving a gain of 15 for both inverting and non-inverting amplifiers.
  • Another participant questions the assumption of using only two resistors for the inverting amplifier and suggests that the listed resistor values may be intended to represent a broader range of values scaled by powers of ten.
  • A different participant proposes using R2 = 10 and R1 = 68 + 82 in series as a potential solution for the inverting amplifier configuration.
  • There is acknowledgment of a previous response suggesting a similar approach, indicating a collaborative exploration of solutions.

Areas of Agreement / Disagreement

Participants have not reached a consensus on the resistor values to use for the desired gain, and multiple approaches are being discussed without resolution.

Contextual Notes

There is uncertainty regarding the interpretation of the resistor values and whether they can be combined in series. The discussion also highlights the potential misunderstanding of the resistor values available.

Who May Find This Useful

Individuals interested in electronics, specifically those working with operational amplifiers and gain calculations, may find this discussion relevant.

qablos
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I have the set of values for resistors available:
10-12-15-18-22-27-33-39-47-56-68-82

And I need to get a gain of 15, which values should I use to get this?

Also, I have a non-inverting amplifier, and again, I need a gain of 15. I selected the values:
R2=12 and R1= 68+82+18=168
I assumed I was able to combine some resistors in series to solve this problem...

Is this correct?
 
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Hi qablos. There are lots of "inverting amplifier" circuits, should we assume you are using an op-amp with just 2 resistors?

You list the resistor values available, as 10-12-15-18-22-27-33-39-47-56-68-82. Are you sure those are all you have? Are they all just Ohms? If so, they are not suitable, resistors of just a few Ohms are too low for most op-amps.

HOWEVER, I think it is probably intended you should understand that the resistances available to you are those values x10n where n is any integer 0..12 or so.

So you have 10Ω, also 100Ω, and 1000Ω, and 10kΩ, and 100kΩ, and 1MΩ, and 10MΩ, etc. Also, 12Ω, and 120Ω, and 1200Ω, and so on ...
 
Quablos, why not use R2 = 10 and R1 = 68 and 82 in series?
 
Oops someone beat me to it.
 

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