Sallen Key Low Pass Filter, bandpass filter

[Maglatron]

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

 

[Maglatron]

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]

hello,

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

bertus

 

[Maglatron]

just tapping the mic, what do you think? thanks

 

[bertus]

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]

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

 

[Martaine2005]

Download the app for a tone generator, it will do the job.

 

[Harald Kapp]

Download the app for a tone generator,

e.g. audacity (see post #905).
Or you can even use LTSPICE to create a suitable wav file.
Or check this list.

 

[Harald Kapp]

@Maglatron : Have you seen this post?

 

[Maglatron]

thanks guys!

 

[Maglatron]

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]

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]

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]

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

 

[Martaine2005]

Thanks for the update.
Double check and triple check YOUR wiring !!

 

[Maglatron]

Thanks for the update.
Double check and triple check YOUR wiring !!

it's comments like that that spur me on so appreciated! thanks

 

[Maglatron]

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]

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]

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]

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