I'm so new in analog electronics. So I stuck with one issue. Let's say I have an input signal, like blue one:It's an AC input signal

To get a DC form I can rectife it (got a grip on it). But what I need is a smooth(regulated), without spikes signal, like red onemy precious

Saturation is optional :) So to get this signal I need to use intagrated circuit with op-amp and NF, like this:s

But my question is next: how to pick values for each component (R39/R40=gain; R40*C37-integral time(not sure); all I know) and what excactly are they responsible for? Or just advise where to dig for info. Will appreciate any answer, friends.

  • \$\begingroup\$ Are you sure you need a low-pass filter or integrator? The blue signal seems to be approximately balanced so you won't see much variation at the output. You may want to use a rectifying circuit instead. \$\endgroup\$ – Sven B Apr 12 '18 at 6:53
  • \$\begingroup\$ Well, if I zoom in the X-scale, it won't be balanced at all, especially for my MC, unfortunately :( \$\endgroup\$ – Vladimir Chizhiumov Apr 12 '18 at 8:59
  • \$\begingroup\$ Well, the reason I'm asking is because this circuit will do both: rectifying + low-pass filtering: hyperphysics.phy-astr.gsu.edu/hbase/Electronic/ietron/rect3.gif You can tune how fast it goes down with R*C. \$\endgroup\$ – Sven B Apr 12 '18 at 9:16

In a nutshell, this is an active low-pass filter.

The parallel feedback RC pair (R39, C37) sets the frequency response ( 3dB cutoff freq = 1/(2*PI*R39*C37) in Hertz )

and -(R39/R40) is the low frequency gain

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  • \$\begingroup\$ You mean even if I have rectified AC signal (which is already DC, but jumping), I stil have to think that it's a low-pass filter, but not the integrator? \$\endgroup\$ – Vladimir Chizhiumov Apr 12 '18 at 8:58
  • \$\begingroup\$ Well, you don't really have a pure integrator by virtue of the feedback resistor R39. \$\endgroup\$ – mike65535 Apr 12 '18 at 13:10

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