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Slew rate block

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xmat

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Hello.

While working in Electronics Workbench, I have noticed a "function" block that performs a "slew rate block" function.

What u can essentially do with it is to set max rate of change of an input signal for both rising and falling parts of it. Faster rising/falling parts of a signal get filtered.

What I wanted to know is if anyone has/knows of an analog circuit that does that (used for low frequency audio signals)..

Better yet, I want to know if there is a circuit that performs a similar yet more advanced function:

U can set minimum AND maximum rising/falling rate of change to pass from the circuit without being filtered..

In that way it could "detect" the part of the signal with the bigger variation in values, and let it pass-by unaltered; while the rest of the signal would be filtered out ...

What' d u think?

Can anyone suggest a schematic?

Many thanx in advance,

xmat.
 
Do you have a short memory? I posted several slew rate limiter circuits for you here. Here's a quote from that thread:
Great... Thanx.

I'll check and report back if the schematics will be usefull.

xmat.
We never got the promised reply.
Regarding a maximum and minimum slew rate limiter: What exactly does a minimum slew rate limiter do? This conjures up a vision of a circuit that create a slope if none is present - sounds like a bad idea. :?
It seems that you are trying to filter transients from audio. Have you ever actually told us what you are trying to do?
 
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Ron H said:
Do you have a short memory? I posted several slew rate limiter circuits for you here. Here's a quote from that thread:
Great... Thanx.

I'll check and report back if the schematics will be usefull.

xmat.
We never got the promised reply.
Regarding a maximum and minimum slew rate limiter: What exactly does a minimum slew rate limiter do? This conjures up a vision of a circuit that create a slope if none is present - sounds like a bad idea. :?
It seems that you are trying to filter transients from audio. Have you ever actually told us what you are trying to do?

Oh dear..I am soo sorry for not doing what I promised..Memory black out.REALLY sorry, honestly.

So, here are some answers:

I tested the simplest of the schematics you suggested (pulse extracto1.gif), due to the fact that they are all based on the same principle (conducting diodes). Here is what I found.

(By the way, below you shall see a schematic of what I am trying to do..It has to something to do with detecting/filtering audio transients in a noisy background.)

The "pulse extractor" u suggested is actually a "limited" version of what I am trying to do to achieve the result depicted in the schematic..(likely the reason I forgot to reply..??..)

U see, it lets fast signals to pass through, yet it filters slow varying parts of the signal by making them quicker.

I don't want that..I want fast varying parts of the signal to pass unaltered, while slow (actually they are also fast but slower than a certain slew rate I can set) parts of the signal to be "smoothen out"..Does this make sense to you?

In case you need more explanations to be able to come up with a solution, please pm me..I don't want to write a 2000 words' post..It can damage someone's eyes and then I will feel guilty.

Thanx for your willingness to help (and sorry again),

xmat.
 

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"...Regarding a maximum and minimum slew rate limiter: What exactly does a minimum slew rate limiter do? This conjures up a vision of a circuit that create a slope if none is present - sounds like a bad idea. :?
...."

Min/max slew rate control I mentioned referred to the circuit's ability to pass only a certain "area" of rate of change unaltered.

The schematics proposed for instance, allow quick-varying parts of signal to pass through unaltered, filtering slow varying parts.
That implies that quicker than the initial quick signals that pass through would also pass through.
I would prefer if that would not happen.Perhaps by having the ability to set min/max rate of change (and perhaps by "narrowing" this "area" down too much it could pass only a specific rate of change....that would be awesome!) that can pass through untouched.

What'd u think?

xmat.
 
A differentiator and a window comparator would allow you to bracket slew rates. The output of the comparator would be high (or low, if you choose) only when the slew rate is between selected limits. I'm not sure what you do with the output - probably control a filter's cutoff frequency. I think Russlk was on this track in the other thread. Why do we have two threads going here?
 
Ron H said:
A differentiator and a window comparator would allow you to bracket slew rates. The output of the comparator would be high (or low, if you choose) only when the slew rate is between selected limits. I'm not sure what you do with the output - probably control a filter's cutoff frequency. I think Russlk was on this track in the other thread. Why do we have two threads going here?

RonH, can you be more specific about the usage of the differentiator in conjuction to the window comparator?I did not quite get HOW the comparator is high or low depending on the slew rate.

Also, I would not want to deal at all with frequency, just rate of change.

That is why the "slope limiter" circuit I showed you in the link

https://www.electro-tech-online.com/threads/opamps-from-everyone-from-ti.16993/


was soo good..Cause it dealt with rate of change and not frequency.

Bottom line, all I want is fast parts signals to pass through and slow parts to become smoother.

Is there an addition to the "pulse extractor1.gif" you can suggest that can do that?That's all I want.

Thanx for your help,

xmat.
 
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xmat said:
Ron H said:
A differentiator and a window comparator would allow you to bracket slew rates. The output of the comparator would be high (or low, if you choose) only when the slew rate is between selected limits. I'm not sure what you do with the output - probably control a filter's cutoff frequency. I think Russlk was on this track in the other thread. Why do we have two threads going here?

RonH, can you be more specific about the usage of the differentiator in conjuction to the window comparator?I did not quite get HOW the comparator is high or low depending on the slew rate.

Also, I would not want to deal at all with frequency, just rate of change.

That is why the "slope limiter" circuit I showed you in the link

https://www.electro-tech-online.com/threads/opamps-from-everyone-from-ti.16993/


was soo good..Cause it dealt with rate of change and not frequency.

Bottom line, all I want is fast parts signals to pass through and slow parts to become smoother.

Is there an addition to the "pulse extractor1.gif" you can suggest that can do that?That's all I want.

Thanx for your help,

xmat.
A differentiator produces a voltage which is proportional to rate of change. This only relates to frequency because, for a given amplitude (sine wave), slew rate increases proportional to frequency. You can't avoid this (with strictly analog processing), no matter how you detect slew rate.
 
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Ron H said:
xmat said:
Ron H said:
A differentiator and a window comparator would allow you to bracket slew rates. The output of the comparator would be high (or low, if you choose) only when the slew rate is between selected limits. I'm not sure what you do with the output - probably control a filter's cutoff frequency. I think Russlk was on this track in the other thread. Why do we have two threads going here?

RonH, can you be more specific about the usage of the differentiator in conjuction to the window comparator?I did not quite get HOW the comparator is high or low depending on the slew rate.

Also, I would not want to deal at all with frequency, just rate of change.

That is why the "slope limiter" circuit I showed you in the link

https://www.electro-tech-online.com/threads/opamps-from-everyone-from-ti.16993/


was soo good..Cause it dealt with rate of change and not frequency.

Bottom line, all I want is fast parts signals to pass through and slow parts to become smoother.

Is there an addition to the "pulse extractor1.gif" you can suggest that can do that?That's all I want.

Thanx for your help,

xmat.
A differentiator produces a voltage which is proportional to rate of change. This only relates to frequency because, for a given amplitude (sine wave), slew rate increases proportional to frequency. You can't avoid this (with strictly analog processing), no matter how you detect slew rate.

So, what with the statement below the picture..Is it false and in what sense?

Have you by any chance thought any solutions?
There must be a way to solve this problem and you were close....I don't even want to think about the potential of you not knowing how to do that.

Thanx for your willingness to help.

xmat
 

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The circuit is a lowpass filter with a -3dB bandwidth of 1/[2*pi*(R1+R2)*C]. In the equations on that schematic, I don't know what Vf means.
I don't know enough about music waveforms to contribute intelligently to this topic, and I am frustrated by what has seemed like just a lot of what we call beating around the bush. I'm gonna bow out of this whole thing unless and until I have an epiphany.
 
Ron H said:
The circuit is a lowpass filter with a -3dB bandwidth of 1/[2*pi*(R1+R2)*C]. In the equations on that schematic, I don't know what Vf means.
I don't know enough about music waveforms to contribute intelligently to this topic, and I am frustrated by what has seemed like just a lot of what we call beating around the bush. I'm gonna bow out of this whole thing unless and until I have an epiphany.

Vf refers to the diodes, the best performance is achieved by using low Vf diodes (Schottky type).

I respect your opinion.

Yet you are free to ask me anything for the circuit that might disolve that sense of "beating arounf the bush".

And many thanx for your help.

xmat.
 
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