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Sallen Key Low Pass Filter, bandpass filter

Maglatron

Jul 12, 2023
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so not had chance to go on my project for a while but not given up, will hopefully update soon!
 

Maglatron

Jul 12, 2023
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so I swapped out the resistors on filter two and still cant get the 45Hz column to react to sound so I'm progressing on to the 3rd column
 

bertus

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Nov 8, 2019
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hello,

what are you using as sound source?
it could be there is no 45 hz in the sound source.

bertus
 

Maglatron

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just tapping the mic, what do you think? thanks
 
Last edited:

bertus

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hello,

do you have speakers on your laptop?
generate a sweep sound in audacity and play that through the speakers into the mic.
the distance between the speaker and mic will change the level.

bertus
 

Maglatron

Jul 12, 2023
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I'll try it speakers on laptop are rubbish though might take a krk speaker with me for the sweep test!
 

Maglatron

Jul 12, 2023
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So, alor, I fixed circuit 1 (I missed two solder-joints and found them when I was duplicating it on the third filter circuit) and now have two columns reacting to sound! making column 3 now.! Work has been extra slow recently due to time constraints but still progressing :) and getting there!! thanks
 

Maglatron

Jul 12, 2023
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now having trouble with the 3rd filter, tut right when I thought I had it! checked and re-checked resistor values and I'm using correct value caps so not sure whats going on atm
 

Maglatron

Jul 12, 2023
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a thought just occured, I may not have put in the ground wire on the envelope detector on filter 3, see later on hopefully
 

Maglatron

Jul 12, 2023
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so I missed two REF ground wires soldered them in and working now!! must have been tired! thanks
 

Maglatron

Jul 12, 2023
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so done half the 4th filter; not missing any wires or things in a step by step methodical manner, just need to do the last stage of the filter and put in the envelope detector - after that make the LM3914 bar graph driver circuit again for the 4th column and that will be 1/4 done!! will make another REF GND circuit because it was suggested that the 1st one would only support 4 filters and LED drivers, will take pics soon, thanks
 

Maglatron

Jul 12, 2023
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so soldered up the rest of the 4th filter and put in the envelope detector, built the 4th set of LED driver chip circuits just have to solder in the LED's power cables the signal wire and a REF GND wire then completed the 4th column will take photo's soon!!!
 

Maglatron

Jul 12, 2023
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something is not right at the moment with the 4th column think I put in a power lead in an incorrect place from the bar graph driver to the LED's, also problem with its filter so I'll go over it again today and take pics when fixed! thanks
 

Maglatron

Jul 12, 2023
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think I know where I gone wrong on the filter, we'll see might not get chance today though
 
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