what is the purpose of C2 in the following example (b)
.... (snip from https://www.nutsvolts.com/magazine/article/op-amp-cookbook)
.... (snip from https://www.nutsvolts.com/magazine/article/op-amp-cookbook)
Any practical op-amp has a so-called offset voltage. That is, when you apply feedback around it, it regulates to some small DC voltage difference between its inputs. If the op-amp circuit has a large gain, the amplified offset may reduce headroom, or burn out your woofer if the path from the op-amp to the woofer is completely DC coupled. Reducing the DC gain to a small enough value prevents that.
At DC, the circuits are both followers, with the positive input connected to ground, so the output is 0VDC.
Except for any DC offset due to imperfections in the op amp.
The capacitors serve to block incoming DC voltage, and to avoid amplifying the inherent DC offset in the op amps.
Also they can reject incoming low frequency disturbances.
Except for any DC offset due to imperfections in the op amp.
The capacitors serve to block incoming DC voltage, and to avoid amplifying the inherent DC offset in the op amps.
Also they can reject incoming low frequency disturbances.
No. The diagram is mislabelled, and the gain shown is incorrect. If the top resistor is taken as R2, the gain (to simplify) is 1+R2/(Z(C2)+R3). At DC, Z(C2) is infinite, so the gain is 1.
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Here is headphone amp project113 which has blocking cap in the feedback. It is flat for 10hz to 100khz
https://sound-au.com/project113.htm
The unity gain mod would be useful for random generators in audio test gear.
https://sound-au.com/project113.htm
The unity gain mod would be useful for random generators in audio test gear.
If you want to be precise, |Z| = 1/(2πfC), but X = -1/(2πfC), and Z = -j/(2πfC). I doubt if that helps fubar3, though.
Thanks for the replies. I like to put these results in a spreadsheet which I can resuse in future. Else I forget and have to reinvent. Here is an example of 3db cutoff.
B8 = 15000 .... R
B9 = 2 .... C
B10 = 1E+06 .... as in 2uf
B11 = 6.28 * B8 * B9 ... calculation #1
B12 = 1/(B11/B10) ... answer = 5.307 ; same as online calculator
I would like to do something similiar for the gain capacitor mystery.
B8 = 15000 .... R
B9 = 2 .... C
B10 = 1E+06 .... as in 2uf
B11 = 6.28 * B8 * B9 ... calculation #1
B12 = 1/(B11/B10) ... answer = 5.307 ; same as online calculator
I would like to do something similiar for the gain capacitor mystery.
I am wondering what this gain-capacitor thing is called so I can look for it on the web. And how is the cap value determined.
Here is a snippet from Rod Elliot Project-11. The gain capacitor (C7) is not discussed on the project page ...
https://sound-au.com/project11.htm