Sallen Key Low Pass Filter, bandpass filter

Maglatron

Jul 12, 2023
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So I drew up a table there are:
19 x AD8657 , 5 quad-op-amps of the same spec in dip package two sets of two, five sets of three
3 x ADA4096-2 , 1 quad-op-amp chip again with the same specs one quad
3 x LT1637 , 1 quad-op-amp chip again with the same specs one quad
5 x LT6015 , 3 dual op-amp chips with the same specs one dual one quad
3 x OP282 , 1 quad-op-amp chip again with the same specs one quad
11 x LT6220 , 3 quad-op-amp chips with same specs three quad 1 dual

I need them all through hole in dip packages!!!
may need help on this part
 
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bertus

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Hello,

You could likely use the TL074 (you already have) for all filters and buffers.
The TL074 might have some worse specs, but you are not going to listen to the outcome of the filters.
The filtertool is likely to promote the Analog chips.

Bertus
 

Maglatron

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lol now you tell me after tabulating variables for 2 and a half hours later oh well no harm done, and I now have the capacitor values and resistors aha so back to an earlier question does it matter the order of the stages because often it doesn't say stage A stage B stage C etc
also I have the capacitor values, which type should I use the lowest value it 1nF 100nF is the greatest
 
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Maglatron

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Hello, so about the stages, does it matter which order the filters go in?
 

Harald Kapp

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does it matter which order the filters go in?
Read here.
Best to use the sequence as proposed by the design tool schematic. Don't be bothered by names liek "A", "B", "C", and "D" etc. These are only names and have nothing to do with the physical arrangement of the circuit parts.
 

Maglatron

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so im going to print out 32 blank (0 value) of the op-amps and label them with pen and paper, the first set of 16 no gain and the second set of 16 with 3dB gain (x2) I've run out of solder for the minute but getting some soon and am going to get to work asap on the filters the LM3914's should arrive today too! also got some LM3915's coming so am going to built the circuit and swap out the chips and see which one has the better desired result! I will post pictures when done that part
 
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bertus

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Hello,

In stead of making a complete series of filters twice, you could add a simple amplifier between the filter and rectifier circuit:
BP_amp.png
That would save you a lot of work.

Bertus
 

danadak

Feb 19, 2021
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For future as you get more experience, the FFT approach in post #43 was minimal
components.

For filter approach same chip can do two filters/chip, using small number chip resources. Example
of 50 Hz and 60 Hz :

1701788621723.png

1701788718530.png

Filter just done with above wizard. Note I did not show 2'ond DAC, also onchip, for the other channel,
just forgot to add it.

Put that in back of your head for future interest.


Regards, Dana.
 
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Maglatron

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Hello I have read your reply and will return to it I'm concentrating on this part as of now
capacitors values and which types to get perhaps I can buy a pack with all of the valuse needed, I really don't want to be mixing values?
all values are in nF
100 x20
91 x2
82 x2
56 x2
62 x2
51 x2
33 x2
39 x2
30 x2
20 x2
18 x2
24 x2
13 x2
15 x2
12 x2
8.2 x2
9.1 x2
6.8 x2
5.1 x2
5.6 x2
4.3 x2
3 x2
3.3 x2
2.7 x2
1.8 x4
2.2 x2
1.5 x2
1.3 x4
1.6 x2
1.2 x4
1.1 x6
1 x6
 

Maglatron

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I'm on mouser and the values are there what type am I looking for?
 
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Maglatron

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ok thank you for the tip because it has taken me litteraly hours to get the resistor valuse from E12 mixes I'm hoping that I don't need to mix capacitor values too I need to know which type of capacitor to use do you know what would work this project is big because the doubled up resistors and the capacitor add up to 384 passive componets and thats excluding the buffers and pre-amp and enveloping circuit or the quad amps and lm3914's, it's no bother though, but it is a lot of work!!
Hello,

In stead of making a complete series of filters twice, you could add a simple amplifier between the filter and rectifier circuit:
View attachment 61950
That would save you a lot of work.

Bertus

1701800882274.png
 

Maglatron

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For future as you get more experience, the FFT approach in post #43 was minimal
components.

For filter approach same chip can do two filters/chip, using small number chip resources. Example
of 50 Hz and 60 Hz :

View attachment 61951

View attachment 61953

Filter just done with above wizard. Note I did not show 2'ond DAC, also onchip, for the other channel,
just forgot to add it.

Put that in back of your head for future interest.


Regards, Dana.
Thank you Dana, I will get round to learning that too, I'm tired right now, it's been a looong day!!
 

Maglatron

Jul 12, 2023
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Hello,

In stead of making a complete series of filters twice, you could add a simple amplifier between the filter and rectifier circuit:
View attachment 61950
That would save you a lot of work.

Bertus
probably a really stupid question but do I need the 12v for power still? I think yes but just to clarify!
nevermind, it was stupid, of course it does!!
 
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Maglatron

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any way protoboard (not strip kind) has 1944 holes so more than enough 100mm x 150mm
 

Maglatron

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Hello, I'm back awake:) could you tell me which type of capacitors that I need to buy please, for the filter circuits?
 
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