3 band trimmer EQ layout

[no one ever]

check for errors? as far as i know, it is completely correct.








from here





oh and I need someone to copy this into a transferable format... I'll email you the original file if needed.

[StickMan]

Does that actually count as an equalizer?  Isn't it just a three knob tone stack?


dave.

[bwanasonic]

I think it is considered a bad idea to run traces between the pins of an IC? Thinks look a bit tight tolerance wise. If you have any thoughts of making more than one, you might want to look at having ExpressPCB make the boards, especially with tolerances that tight, and the ground plane design. If you can fit four circuits on a 3.8"X5" miniboard, it brings the per-board cost down to under $5@ (3 miniboards for $59).

Kerry M

[Joecool85]

Does that actually count as an equalizer?  Isn't it just a three knob tone stack?


dave.

It counts.  I would count it since it is an active 3band EQ.  If it was just the 3 bands that cut, I would probably refer to it as a tone stack.  But in all reality, even that is an equalizer.

[no one ever]

I think it is considered a bad idea to run traces between the pins of an IC? Thinks look a bit tight tolerance wise. If you have any thoughts of making more than one, you might want to look at having ExpressPCB make the boards, especially with tolerances that tight, and the ground plane design. If you can fit four circuits on a 3.8"X5" miniboard, it brings the per-board cost down to under $5@ (3 miniboards for $59).

Kerry M

it's a ground trace though... didn't know there were any special trace guidelines for (relatively) low voltage applications like this.

[coitmusic]

Here's a good description of how to get around all the trash in ExpressPCB and print out a transferable layout:
http://www.robotroom.com/PCB.html

I haven't done too many boards, but I agree that running that trace between the pins might be a challenge if you're etching this board at home. Mostly about tollerances and trace widths. Try switching the orientation of the two caps at top left and the resistor (and a lot more stuff I'm sure) The idea being to bring the two branches of that trace together on the left side of the chip so you won't have to run that trace between the pins. Sorry if this isn't helpful, but I don't have the time today to try my hand at the layout.

Chester

[Pushtone]

Nice layout No One Ever! I want to hear it.
Just what I was looking for, how timely - me want to build!

I volunteer make a transfer for this. And output a gif or pdf file (like the ones on GGG) for use with PnP Blue.
I would want to make a few boards for personal use.
Perhaps a jumper on the component side for that trace going between IC pins.
Message me if you would like me to post my transfer.

Pushtone

[Pushtone]

I just saw the link to the schem.

Problem is the freq. centers of 50Hz, 1kHz and 10kHz are not so great for guitar.
Can these be tuned to more guitar friendly frequencies by changing caps?
I'm thinking 200Hz, 630Hz and 2kHz depending on how wide these filters are.
I could learn something by building this.

Pushtone

[johngreene]

I think it is considered a bad idea to run traces between the pins of an IC? Thinks look a bit tight tolerance wise. If you have any thoughts of making more than one, you might want to look at having ExpressPCB make the boards, especially with tolerances that tight, and the ground plane design. If you can fit four circuits on a 3.8"X5" miniboard, it brings the per-board cost down to under $5@ (3 miniboards for $59).

Kerry M

it's a ground trace though... didn't know there were any special trace guidelines for (relatively) low voltage applications like this.

Why even bother routing the ground with a trace when you have it connected to the copper everywhere anyway?

--john

[no one ever]

I think it is considered a bad idea to run traces between the pins of an IC? Thinks look a bit tight tolerance wise. If you have any thoughts of making more than one, you might want to look at having ExpressPCB make the boards, especially with tolerances that tight, and the ground plane design. If you can fit four circuits on a 3.8"X5" miniboard, it brings the per-board cost down to under $5@ (3 miniboards for $59).

Kerry M

it's a ground trace though... didn't know there were any special trace guidelines for (relatively) low voltage applications like this.

Why even bother routing the ground with a trace when you have it connected to the copper everywhere anyway?

--john

exactly! new layout coming out in a bit (shorter height, longer width, as this is designed to be mounted on the side wall of an enclosure, along with other improvements)

[no one ever]

Nice layout No One Ever! I want to hear it.
Just what I was looking for, how timely - me want to build!

I volunteer make a transfer for this. And output a gif or pdf file (like the ones on GGG) for use with PnP Blue.
I would want to make a few boards for personal use.
Perhaps a jumper on the component side for that trace going between IC pins.
Message me if you would like me to post my transfer.

Pushtone

that would be great! thanks for offering 

i'm sure a few R/C value changes will make this more guitar friendly. i'm short of time to do the math right now though.

here ya go! thicker traces, more clearance.

[Pushtone]

Cool I'll do the trace tonight.

So this is to go on the wall of the enclosure. If so, it should be no taller than say... 22mm for a 1590B. Your layout will be taller than that by the looks of it.

[no one ever]

Cool I'll do the trace tonight.

So this is to go on the wall of the enclosure. If so, it should be no taller than say... 22mm for a 1590B. Your layout will be taller than that by the looks of it.

I'm putting it on the wall of a 2" high enclosure (univibe, smalbear 1690ns)... I believe I have breathing room in that case?

[no one ever]

Cool I'll do the trace tonight.

So this is to go on the wall of the enclosure. If so, it should be no taller than say... 22mm for a 1590B. Your layout will be taller than that by the looks of it.

I'm putting it on the wall of a 2" high enclosure (univibe, smalbear 1690ns)... I believe I have breathing room in that case?

yep i do (checked)

[Pushtone]

Here's the transfer. Did I get it right?
http://www3.telus.net/david65/pedal-pics/3BandEQ-PCB-FOROUTPUT.pdf

Oops I already see two traces that are too close together.
Please check it before I update it.

Thanks
Pushtone

[Pushtone]

Would I be wrong to think this circuit would have an input impedance of around 10k?
I'm thinking a buffer before the EQ would be a good idea.
It would add 2 or 3 cm to the legnth.

[no one ever]

Here's the transfer. Did I get it right?
http://www3.telus.net/david65/pedal-pics/3BandEQ-PCB-FOROUTPUT.pdf

Oops I already see two traces that are too close together.
Please check it before I update it.

Thanks
Pushtone

Thank you very much, Pushtone!


I'll get on the buffer...

[no one ever]

whew! quickest layout i've ever made. thanks Jack for hosting such a plethora of schematics.. including buffers  (see miniboost page at muzique for schem)



and trace



oh and a note: this layout uses the inverting output... should I have used the non-inverting second output?

[Pushtone]

(see miniboost page at muzique for schem)
oh and a note: this layout uses the inverting output... should I have used the non-inverting second output?

Do you mean to say you used the mini-booster for the buffer? I just built one a while back and it wouldn't be my first choice for this application. I love the sound of the mini-booster but I think this circuit calls for a clean 1:1 buffer. The mini-boostr is half to three quarter the way to a fuzz box. Its a dirty preamp, or should I say, sounds like tube grit, which is what it's suppose to do. I'm going to call mine True Grit because if John Wayne had played guitar, he would of used a mini-booster.

Anyway..., is there anyway I could talk you into a layout using a TL072? The IC buffer at GGG perhaps?

About the non-inverting output... yeah it should not invert the phase unless there is to be another inverting amp used after the EQ circuit.  I f I understand right, this little EQ could be inserted after a BSIAB circuit to boost bass respone or something. SO, if this is right, it should have a high impedance input (buffered) and a low impedance, non-inverted output.

[no one ever]

Do you mean to say you used the mini-booster for the buffer? I just built one a while back and it wouldn't be my first choice for this application. I love the sound of the mini-booster but I think this circuit calls for a clean 1:1 buffer. The mini-boostr is half to three quarter the way to a fuzz box. Its a dirty preamp, or should I say, sounds like tube grit, which is what it's suppose to do. I'm going to call mine True Grit because if John Wayne had played guitar, he would of used a mini-booster.

Anyway..., is there anyway I could talk you into a layout using a TL072? The IC buffer at GGG perhaps?

About the non-inverting output... yeah it should not invert the phase unless there is to be another inverting amp used after the EQ circuit.  I f I understand right, this little EQ could be inserted after a BSIAB circuit to boost bass respone or something. SO, if this is right, it should have a high impedance input (buffered) and a low impedance, non-inverted output.

hmm.. alright then. the article says the output is unity gain, but i'll whip up an alternate buffer anyways.