Inverting Op Amp Low Output (What am I missing?)

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Eet3m
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Post by Eet3m »

Hi,
I'm trying to make an inverting op amp buffer as I want to flip the phase and buffer the signal. I've attached a photo of my breadboard and the circuit I'm trying to follow.
When I connect it all up, the output is super low, -30dB or so from where I started, and it looks like my signal is being low passed. I've tried a few different resistor values from 1M to 10k for both resistors with more or less the same result. Also tried a TL072 op amp, also no luck.
I assume I'm missing something pretty obvious here since the circuit is pretty much as simple as it gets.
Should I be using a different op amp, different resistor values? Have I wired it backwards or am I missing some other key component altogether?

Thanks in advance!
Dan
IMG_0912.jpg
Op amp.png
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blackboarcult
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Post by blackboarcult »

I think you should have the noninverting input connected to Vbias and not ground, since you are not powering the opamp with a bipolar voltage source.
Also, I'd put a coupling cap (100n to 10u depending on what resistor values you have or what comes before) between input and Rin.
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Eet3m
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Post by Eet3m »

Great thanks for that, I’ll give it a try this afternoon.
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