Hello again,
Here is a circuit.
The calculations for R1 and C1 are:
R1*C1=1/(4*F)
where F is the frequency (33Hz) so if you are using R1=1.1k then you need C to be 1/145200 Farads.
C2 is selected to have reactance less than 1 percent of R1 at 20 times the frequency F (F=33Hz).
This value is not critical as long as it is large enough.
Note R2 was made to be 1 megohm (1000k) and the output still looked decent even though there is a small output offset. You may have to go lower than that though in the real circuit.
If you still get those spikes then try using the post filter shown in the lower right hand corner of the drawing. Connect it to the output, and you may end up needing a buffer or you could try lower values of R4 with proportionally higher values of C4.
Note the output shown in the drawing though, using the LM358 spice model i had did not show any spikes, but in real life there probably will be anyway so consider the output filter if so.
Here is a circuit.
The calculations for R1 and C1 are:
R1*C1=1/(4*F)
where F is the frequency (33Hz) so if you are using R1=1.1k then you need C to be 1/145200 Farads.
C2 is selected to have reactance less than 1 percent of R1 at 20 times the frequency F (F=33Hz).
This value is not critical as long as it is large enough.
Note R2 was made to be 1 megohm (1000k) and the output still looked decent even though there is a small output offset. You may have to go lower than that though in the real circuit.
If you still get those spikes then try using the post filter shown in the lower right hand corner of the drawing. Connect it to the output, and you may end up needing a buffer or you could try lower values of R4 with proportionally higher values of C4.
Note the output shown in the drawing though, using the LM358 spice model i had did not show any spikes, but in real life there probably will be anyway so consider the output filter if so.
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