Mad Professor - Snow White Auto Wah  [traced]

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jmwreck
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Post by jmwreck »

riesling wrote:
Dr. Nöres wrote:Why did you replace the LM324 by two TL072?
1. I have at least 20 TL072
2. I don't like Quad OP-Amps (just a personal thing)

But feel free to change the layout to your needs :)
in short, can i replace the LM324 and your 2 x TL072 with a TL074?? :)

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Post by roseblood11 »

Is it possible to add a switch that reverses the filter sweep?

That´s an interesting mod for the MXR Envelope Filter (see tonepad.com), but I think it would sound much better with the SWAW, because the overall sound is better.

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Post by jmwreck »

hello to everyone, i have redrawn the schematics based on the one posted here, and i have matched it with dimebug's layout. i have found out that the LM324 pinouts in the schematics was arranged in a different way with regards to the layout. I have been thankful for both the scheme and layout. Im just concern of the pins of LM324 specifically the COMMON pins.

correct me if im wrong with this :D

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roseblood11
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Post by roseblood11 »

lm324 contains 4 opamps that are completely identical...

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jmwreck
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Post by jmwreck »

roseblood11 wrote:lm324 contains 4 opamps that are completely identical...
subconsciously, thats what i thought, im never an expert on this, thanks roseblood! :D

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Post by roseblood11 »

you don´t need to be an expert to search the datasheet at alldatasheet.com... :wink:

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Post by the_ungod »

Hi there...

Where can i get a verified schematic?

Thanks

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Post by roseblood11 »

the_ungod wrote:Hi there...

Where can i get a verified schematic?

Thanks
May I suggest a very simple idea:

R E A D T H E T H R E A D ! ! ! ! ! :scratch:

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the_ungod
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Post by the_ungod »

I've read it already, just wanna be sure...

But thanks anyway for your kindness...

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vorokha
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Post by vorokha »

The thread may already outdated, but I want to ask colleagues to do this pedal - attached diagram is correct, if not, please indicate my mistakes.
Thanks in advance.
Attachments
snowwhite.pdf
(21.19 KiB) Downloaded 1082 times

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Ice-9
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Post by Ice-9 »

vorokha wrote:The thread may already outdated, but I want to ask colleagues to do this pedal - attached diagram is correct, if not, please indicate my mistakes.
Thanks in advance.

A quick look over and everything looks fine.
It's fairly straight forward, if you want to start it , press start. You can work out the rest of the controls for yourself !

No silicon heaven ? preposterous ! Where would all the calculators go ?

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Post by devastator »

about the lm13700, are they fragile ?

I soldered some wire (for the pots) and the enveloppe doesn't work any more (but the sound still there)

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Post by mictester »

uncleboko wrote:Vista will not open .sch files, what is the workaround please?
You need the "Eagle" software. It's free from Cadsoft.
"Why is it humming?" "Because it doesn't know the words!"

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vorokha
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Post by vorokha »

devastator wrote:about the lm13700, are they fragile ?
I soldered some wire (for the pots) and the enveloppe doesn't work any more (but the sound still there)
Maybe you're not power off when soldering?
I did a lot of their Phasers on these chips, their scheme in 4 pieces, I was not the case that they were burned.

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Post by devastator »

yes, no power going into. But the chip stay in place when I put the wire.

I can hear the decay and sensitivity control act on sound, but any sweep or "quack" is presents. The signal goes into the filter whitout being changed (like a fixed wah ) .

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Post by ckyvick »

devastator wrote:The signal goes into the filter whitout being changed (like a fixed wah ) .
Are you sure its not how you have it set? because it does a fixed wah too. if not it sounds like your wiring

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Post by devastator »

i'll check it tomorrow again. Maybe I did something wrong indeed.

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waaap
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Post by waaap »

Hi,
i'm from japan and sorry for my poor English

I made one using NJM13600 because LM13700 or NJM13700 is hard to get in japan (or it's so expensive)
and the results were discouraging.   So I ordered LM13700 from overseas with expensive shipping charge,
So I'll report soon.

Anyway , thanks for great project !

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Post by Ice-9 »

waaap wrote:Hi,
i'm from japan and sorry for my poor English

I made one using NJM13600 because LM13700 or NJM13700 is hard to get in japan (or it's so expensive)
and the results were discouraging.   So I ordered LM13700 from overseas with expensive shipping charge,
So I'll report soon.

Anyway , thanks for great project !
To be Honest the NJM13600 should just drop in place of the 13700. You should get very similar results if not the exact. What exactly is the problem you have with the effect ?
It's fairly straight forward, if you want to start it , press start. You can work out the rest of the controls for yourself !

No silicon heaven ? preposterous ! Where would all the calculators go ?

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waaap
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Post by waaap »

Sorry for late reply.
The reason for getting strange sounds is burned 78L05, because I mounted it reverse.
Replace of 78L05 (to 78L005 Toshiba), get good result.

I received LM13700, but not tested yet. I'll try when my cold is gone. :oops:

thanks,

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