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# NonInverting Amp

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#### herbymcduff

##### New Member
I need help with this one. I'll give parts needed and a description of what I need.

Parts:

1 op amp
1 cap
Resistors
1 POT

Can you draw me a noninverting amp that will take a 500mV p-p low level signal and amplify it to 100mV p-p to 2V p-p (adjustable)

I was just wanting to see what any of you guys or girls come up with. I want to compare it to mine and see if mine is correct or not.

The trouble I have, is that in my mind I don't think you can get out 100mV p-p. Mainly because gain is determined by RF/R1 +1 right. So even if you had a gain of .1 on the inverting, +1 you would get 1.1. With an output voltage of .550mV p-p.

After thinking about it for awhile, I finally came up with putting a voltage divider on the noninverting input. If I am right, I don't know. That's why I am asking you.

Thanks.

Potential divider will work just fine as you want. Just keep the gain of op-amp to 4 so that when the input is 500mV and the potential divider is set for minimum attenuation, the output will be 500*4=2000mV=2V.
To get 100mV for 500mV input, adjust your potential divider such that the input signal to NI pin is 25mV. The output is this case will be 25mV*4=100mV.

Bye the way where are you going to use that capacitor which you mentioned in your list?

Since I'm putting in a AC signal, I'm using the cap to block DC coming in on the noninverting input.

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