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Simple lpf filter
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urbanspaceman



Joined: Feb 26, 2008
Posts: 67
Location: italy

PostPosted: Wed Jul 01, 2009 6:03 pm    Post subject: Reply with quote  Mark this post and the followings unread

Ok, 2nd Round.
Talk!


Low pass filter pcb_v3.jpg
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Low pass filter ExpressPCB.rar
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urbanspaceman



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PostPosted: Fri Jul 03, 2009 2:20 pm    Post subject: Reply with quote  Mark this post and the followings unread

no comment?
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Adam-V



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PostPosted: Sun Jul 05, 2009 4:54 pm    Post subject: Reply with quote  Mark this post and the followings unread

I would make the pads and traces much fatter. Bigger pads will make it easier to solder and reduce the risk of the pads lifting with excessive heat.

The pads on the IC could be made twice their current size and the pads for the other components slightly bigger. Leave the hole size the same though. I would make the traces as wide as the current pad size.

Other than the size of the pads and traces it looks like a nice little layout.

Cheers,
Adam-V

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urbanspaceman



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PostPosted: Mon Jul 06, 2009 4:12 am    Post subject: Reply with quote  Mark this post and the followings unread

ok, I have increased the size of the tracks and some pad (the pad of the components are not able to increase them with ExpressPCB)


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Adam-V



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PostPosted: Mon Jul 06, 2009 3:53 pm    Post subject: Reply with quote  Mark this post and the followings unread

Looking good!.

For the components where you can't change the pad size (there probably is a way to do it but I can't say - I'm a protel person) maybe you can place larger single pads over the top of the existing ones to increase their size?

Cheers,
Adam-V.

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urbanspaceman



Joined: Feb 26, 2008
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PostPosted: Tue Jul 07, 2009 12:57 am    Post subject: Reply with quote  Mark this post and the followings unread

the program does not let me enter.
should modify the component in the library
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Adam-V



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PostPosted: Tue Jul 07, 2009 3:49 pm    Post subject: Reply with quote  Mark this post and the followings unread

That would be the best solution then the components will be correct when you do your next board.

Cheers,
Adam-V

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urbanspaceman



Joined: Feb 26, 2008
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PostPosted: Tue Aug 18, 2009 3:24 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi, this is my first attempt to design a veroboard version of this filter.

What do you think?
I used a free DIY layout creator by Storm Software, his website is down. This is the best free software for vero?
Tnx


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comrade_zero



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PostPosted: Thu Aug 27, 2009 10:08 pm    Post subject: Reply with quote  Mark this post and the followings unread

If you (or anyone) is still playing with this circuit, I just wanted to mention I threw together a dual version using a TL082 (dual op-amp) instead of the single 741. Using the same component values as shown it seems to be a little less "aggressive" and harder to push into self oscillation. However, when you run the output of the first filter into the input of the second and start twisting knobs, well, I don't really know what to call the sound, but I like it.
For anyone out there needing a simple filter for tweaking out (or mangling) a sound, I would readily recommend it.

So, how did your PCB go? did you etch it? Or was this more of a design exercise?
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urbanspaceman



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PostPosted: Fri Aug 28, 2009 1:11 am    Post subject: Reply with quote  Mark this post and the followings unread

for now I just designed the circuits I have not tried yet.
have a design of your version?
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ogg



Joined: Sep 30, 2009
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PostPosted: Sun Oct 04, 2009 4:29 am    Post subject: Reply with quote  Mark this post and the followings unread

comrade_zero wrote:
If you (or anyone) is still playing with this circuit, I just wanted to mention I threw together a dual version using a TL082 (dual op-amp) instead of the single 741...


Hi, I just found your LPF and put a simulation of it on Music Circuit Simulations. It's impressive for such a small circuit. Would you post your dual op-amp version?

Hope you don't mind me putting it online, I have credited you and linked to this thread.

Cheers,

Ollie
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v-un-v
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PostPosted: Sun Oct 04, 2009 5:22 am    Post subject: Reply with quote  Mark this post and the followings unread

Nice filter! Cool

Very sweet resonance. Very musical. Very Happy

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ogg



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PostPosted: Sun Oct 04, 2009 9:27 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi, I just build the filter on a breadboard and it doesn't seem to be working.

Changing the frequency affects the volume but there's no clear change of tone. Changing the resonance resistor value, or removing it, isn't having any effect (I used a resistor rather than a pot for P1). Also connecting and disconnecting the power makes no difference to the sound!

Is it possible to diagnose from what might be wrong with my setup from these symptoms? I'm not sure where to start trying to fix it.

Cheers,

Ollie
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v-un-v
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PostPosted: Sun Oct 04, 2009 12:26 pm    Post subject: Reply with quote  Mark this post and the followings unread

It could just be because your online Spice simulator is actually a pile of shite, and what you really need to do is to get some half decent software? Spice? Rolling Eyes Laughing
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ogg



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PostPosted: Sun Oct 04, 2009 1:21 pm    Post subject: Reply with quote  Mark this post and the followings unread

Is that actually an acceptable tone on this board and how you would usually address someone or a rude anomaly?
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v-un-v
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PostPosted: Sun Oct 04, 2009 3:22 pm    Post subject: Reply with quote  Mark this post and the followings unread

Good question.

Generally I think people are pretty candid here on electro-music.com. We have only ever banned one person. I tend to be rather outspoken, I think most people think I must be a bit of a gobshite, which;

a) They are entitled to their opinion

and

b) they are probably right! Laughing

As I said, welome to electro-music.com! Of course if you just want to be outright rude, then most people will ignore you, but I think that is fair to say is the case of most places, including in down the pub Wink Very Happy

Gotta sleep now. Again, welcome to the forum Very Happy

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v-un-v
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PostPosted: Sun Oct 04, 2009 3:32 pm    Post subject: Reply with quote  Mark this post and the followings unread

v-un-v wrote:
It could just be because your online Spice simulator is actually a pile of shite, and what you really need to do is to get some half decent software? Spice? Rolling Eyes Laughing


Shocked Okay I just read what I wrote. Okay, I see that you are reading it another way. I tend to say things tongue-in-cheek, but sometimes I am read as being rude. I wasn't trying to be rude. Smile

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elektro80
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PostPosted: Sun Oct 04, 2009 3:51 pm    Post subject: Reply with quote  Mark this post and the followings unread

Ups.. perhaps that was a bit crass, Tom?
Idea

Do as I do, blame your not so dormant viking genes! Laughing

That being said, I also often blame 21th century mass market ale. The brilliant scot single malt Caol Ila is way more agreeable. Right.. did I miss something?

HI ogg! welcome

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elektro80
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PostPosted: Sun Oct 04, 2009 3:54 pm    Post subject: Reply with quote  Mark this post and the followings unread

v-un-v wrote:
Shocked Okay I just read what I wrote. .... but sometimes I am read as being rude. I wasn't trying to be rude. Smile



Nah.. but you managed well anyway. ( ducking )
You gotta sacrifice 2 goats for this one. You hear? Laughing Laughing Laughing

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comrade_zero



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PostPosted: Mon Oct 05, 2009 12:51 am    Post subject: Reply with quote  Mark this post and the followings unread

Ogg:
1) no problems from me from me putting a simulation on your site, and thank you for linking to this thread.
2) I wouldn't suggest using a resistor instead of P1. (I assume you are building from Urbanspaceman's strip layout?)
The Sallen-Key filter topology (for low-pass) relies on two resistors of the same value to determine cutoff. To make this filter dynamic you would use a dual-ganged (stereo) potentiometer for these two resistors to allow you to vary the cutoff frequency.
3) As for the dual version give me a couple of days to draw one up. I am thinking of switching it between series and parallel with a DPDT switch.

Let me know if I can be of assistance.
Thanks, hope this helps.
c_z
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v-un-v
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PostPosted: Mon Oct 05, 2009 1:08 am    Post subject: Reply with quote  Mark this post and the followings unread

Oh wise gothic master, I've drunk the blood of four goats, and poured the remaining blood over my head. Next time, I'll drink one less tankard containing the fly agaric infused reindeer piss. Idea
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ogg



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PostPosted: Mon Oct 05, 2009 3:06 am    Post subject: Reply with quote  Mark this post and the followings unread

v-un-v wrote:
Shocked Okay I just read what I wrote. Okay, I see that you are reading it another way. I tend to say things tongue-in-cheek, but sometimes I am read as being rude. I wasn't trying to be rude. Smile


Okay, no worries Cool
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v-un-v
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PostPosted: Mon Oct 05, 2009 3:15 am    Post subject: Reply with quote  Mark this post and the followings unread

Now that I've been a good little Viking, I've paid more attention to your simulator, although I haven't done anything with it yet. Interesting! Perhaps you could explain what gives? Cool
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v-un-v
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PostPosted: Mon Oct 05, 2009 3:22 am    Post subject: Reply with quote  Mark this post and the followings unread

comrade_zero wrote:

The Sallen-Key filter topology (for low-pass)


I'm presuming then, if you switch the resistor and capacitor around, we get high pass?? Question

I've seen this design of VCF (or should I say ICF?) countless times in American books and stuff (wah-wah pedals??). I should have paid more attention as it sound great! It's a beautiful circuit for the lunettas! Cool

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ogg



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PostPosted: Mon Oct 05, 2009 4:46 am    Post subject: Reply with quote  Mark this post and the followings unread

v-un-v wrote:
Perhaps you could explain what gives? Cool


Actually the simulator seems fine with this circuit, it's my breadboard that's not working. I have the symptoms I described above and wondered if the problem could be diagnosed from them.

Having re-wired it again and checked the contacts I think the problem is that the batteries were loose!
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