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Sallen Key Low Pass Filter, bandpass filter

bertus

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Nov 8, 2019
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hello,

strange, you do have an account over there.
you made already 154 posts over there.
you likely will have to login to view the page.

bertus
 

Maglatron

Jul 12, 2023
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do all chips have similar bypass cap value or does it matter which type of chip being used?
 

Maglatron

Jul 12, 2023
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HOORAY!! One column reacting to sound forgot to take pics of the soldering, also think I soldered the LED's in wrong because the light went from the ends to the middle so desoldered the top section of the LED's and then eyes got tired so didn't have chance to solder the top one back in, but here you are results:
 

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Maglatron

Jul 12, 2023
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anyway, I used the REF GND on the amp the filters and the two LM3914, how many more circuits can I use that REF GND for?? because I know you said that one REF GND would support four filters but with the LED bar graph drivers will one REF GND still support four filters and four sets of LM3914's please, thanks
 
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Maglatron

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so I got a channel to work and nobody has even commended me for achieving this and wanted you all to know that talking me through it was not a waste of time! but thanks for spurring me on!! otherwise I don't think I'd have gotten this far!! the column/channel reacts to sound and moves up and down with volume and snapping of fingers and is working in bar graph mode! going to start channel two asap! thanks
There's 'bugger all' to the basic design of the filter section that couldn't be actually, physically constructed (on protoboard or hardwired) with sockets for the relevant resistor/capacitor values and you could play to your hearts content until you found something that worked.

How about building ONE channel that actually works?

It would be a damned sight quicker than a 700+ post regime and save some members time too.

It would also be nice for those who have taken the time and effort to assist in this thread to see something PRACTICAL from all their input. A few displays on some board doesn't cut it.

And if you haven't got a grasp of it by now then you need to reconsider your approach.
 
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Maglatron

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starting second filter now and will proceed onto the bar graph LED drivers too
 

Maglatron

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so not finished the second filter yet, I've connected the first stage of the filter, the REF GND's and the power and GND to the TL074, and went to show someone the first column lighting up with sound but the LED's of the first column just stayed on, so I snipped the REF GND's of the sectond circuit and lo and behold it worked again so left me wondering, is the second circuit interfering with the first column circuits or maybe was thinking finish the circuit and it may work?
 

bertus

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hello,

does the ref voltags change when you connect the second lm3914?

bertus
 

Maglatron

Jul 12, 2023
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hi there Mr Bertus like I said I was half way through making the second circuit when I went to show someone the lights of the first one so the TL074 I have one hooked up the fist stage of the second filter the ref and power going on it right now so will be able to tell youy if the ref has changed within 5 mins
 

Maglatron

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so the first column is working to a degree asin all leds light but not from the bottom up the intensity of sound makes ALL led go from dim to bright with volume just soldering in the wires so it's the same as before and will measure the voltage on ref
 
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Maglatron

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so I missed a solder joint on the ref from the 1st filter and now when I turn it on the led's initiate from the top down, doesn't miss any leds so I presume i've wired it right doesn't react to sound though anymore, also mesured between pin 4 and 5 of the chip one of the lm3914 and it measures 2.8v
 
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Maglatron

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any ideas?? the REF GND doesn't change when the second TL074 is powered up! still have to make the second set of LM3914's the first column isn't reacting to sound!! when the REF GND was not connected the column of LED's was reating to sound but not going upwards, all of the LED's were lighting and ALL we getting brighter with volume!!
 
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Maglatron

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Why are the bar graph LED's not lighting and reacting to sound in sequence from bottom to top for the 45Hz column please? thanks! grasping at straws here but could it have something to do with the voltage being 2.8v and not 2.4v between pins 4 and 5 on the first LM3914 chip in the circuit for column 1
 
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Maglatron

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so I'm going to proceed to making the whole of the second circuit and if it works then I know that I messed up on the first circuit! if it turns out the same then I know that there's a problem with the circuit design!
 
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Maglatron

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got a session from 1 till 3 today should be enough time to see whats going on!
 

Maglatron

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so I built the second filter and now started on the second set of bar graph LED drivers (LM3914's) my eyes got tired around 2 O'clock so coulnd't carry on hopefully get a go later!
 

Maglatron

Jul 12, 2023
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so alor THE SECOND FILTER AND BAR GRAPH LED'S ARE REACTING TO SOUND NOW, AND REACTING IN THE CORRECT WAY FROM BOTTOM UP!! so now I know that the first circuit I made was infact wrong!! and so now I can fix!!! will have pics latest tomorrow perhaps tonight! thanks as you see in the pics I've removed all the circuitry from the first column drier circuit an am going to fix next session, I know this has been a bit like boy cries wolf but I have it this time round ;)
 

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