This is a library of perfboard and single-sided PCB effect layouts for guitar and bass. I'm not an electrical engineer by any stretch of the imagination, just a DIY'er who likes drawing layouts. It is meant for the hobbyist (so commercial use of any of these layout is not allowed without permission) and as a way to give back to the online DIY community.

Monday, January 4, 2016

Mad Professor Snow White AutoWah

Happy New Year, everybody! I hope this year brings you all joy and much soldering. :)

By popular demand, I give you the Mad Professor Snow White AutoWah. Now stop pestering me for it. ;) This was a pretty complicated circuit to fit on a single-sided board, so there are a few jumpers (one of which is super long–bugs me, but it was the only way to make it work), but if you play your cards right you should be able to squeeze it into a 1590B like the original.


28 comments:

  1. finally, SWAW has arrived.
    happy new year to you brother!!!

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  2. Thank you so much!!!! I have really been wanting to build this. YOU ROCK!!!!!

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  3. Hi, I found a difference between the layouts; pin 4 of the LM324 is connected differently, what is the correct one?

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    1. Whoops. I'll fix it. The PCB side is correct. Pin 4 of the 324 goes to the voltage rail. Thanks for catching that.

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  4. Would I be able to replace the 2N5457 with a BF244A as long as I correct the pin placement?

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  5. You could socket and try, but the datasheets aren't all that similar. Probably best to stick with the 5457.

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    1. Ok, thanks for the reply. I haven't been able to get my hands on a 5457 since they have been discontinued.

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    2. I guess I could try ordering some Chinese ones from eBay.

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    3. Ok, so I did some googling, and the BF245A came up several times as a replacement for the 5457. Can you get those?

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    4. I had a hard time finding them on Tayda's website. I tried the BF245B and the BF244A. Not sure if it's the FET that's the problem, but there is something very off with my build.

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  6. Hi, thanks you for your work.
    My Snow White work bad. My problem is that I hear only a continuous buzzing sound when I press the swich. The buzz up and down by operating the BIAS potentiometer, but also up and down a bit by operating the RESONANCE, but less. I've been looking for the solution reading post and watching the electric scheme, but I can not find it. I checked everything but everything seems fine. I have printed the circuit and I have followed it too and I have bought again the main components to check one by one but it is the same. Any idea?

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  7. I built this yesterday. i can't test it yet because I thought I had some LM324 chips but only have TL074 and LF347. Those both pull the rail down too much. Maybe if I bypass the 47R but I think I will just wait for my order to arrive and just install the LM324. I'm posting right now because it seems the 100uF cap is connected wrong. I believe it should go from + rail to ground. As drawn above it connects pin 13 of the LM13700. Can you confirm this?

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  8. And is it posible that by this I were hearing the sound of ground (my buzz)?

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  9. Confirmed. It was the incorrect positioning of the capacitor in PCB. The + of capacitor has to go in V + (red line of PCB).

    Thanks

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    1. Yes, that would be the problem. I'll fix that in the layout. Thanks for catching that and glad your sorted it out!

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    2. I have been taking information and in some webs is recommended to change some components (D5 1N4148, R18 47K, D6 1N2A4 and C8 1uf) because them improve the sound.
      I have repared the error with the capacitor (C7) and I have added that changes and it sounds great

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  10. Have any of you tried using TL074 for A1? I am still waiting for some LM324s to come in I have tried it with the TL074 and can't get it working. I see a few layouts that use a pair of TL072s so I thought the TL074 would work. Can it work with maybe some changes?

    Thanks, Terry

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  11. Does anybody build it? Works great?

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  12. Confirmada la ultima versión. Gracias por la información. Saludos

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  13. Hello, I have mounted this circuit but I have no sound, I have checked everything and it is corrector according to the design of the pcb, somebody help me ????
    thanks and regards

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  14. Hi, i had trouble with the decay pot, it didn't worked 'til i changed the 4k7 resistor(r27 in schematic) in series with it for a 47 ohm resistor, like it shows in this schematich ttps://elektrotanya.com/PREVIEWS/63463243/23432455/egyeb/mad_professor_snowwhite_autowah_guitar_effects_schematic.pdf_1.png

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  15. Hello your blog is awesome !!! .... i see i don't have 2N5457, Lm324, Bc550c lol but i have J201, TL074 and Bc547/48/49 so if i'm replace that would be oke ??

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  16. Hello, how to modify it for bass use? like Snow White Bass Auto Wah.
    thanks in advance.

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  17. hello, I have the pedal working but improvised, I explain with the in normal PCB mode no sound comes, nothing is heard but the pedal is active and if I move the pots they act because the filtering is heard in the departure.
    In a casual way checking the copper and solder tracks I made a bridge between the in and the polyester condenser track of 220nf, in the positive leg that goes from the 1uf electrolytic to this capacitor, in this way if I have an input signal and the pedal works, can you help me find the problem because I do not get the signal for the pc in?
    everything is ok, solders, components and copper tracks of the pcb, I have repeated the project twice and both have given the same problem.
    Thanks in advance and greetings

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  18. hola, tengo el pedal funcionando pero de manera improvisada, me explico con el in de modo normal de la pcb no llega sonido, no se escucha nada pero el pedal esta activo y si muevo los pots estos actuan por que se escucha el filtrado en la salida.
    de manera casual revisando las pistas de cobre y soldadura hice un puente entre el in y la pista del condensador de poliester de 220nf, en la pata positiva que va del electrolitico de 1uf a este condensador, de este modo si tengo señal de entrada y el pedal trabaja, pueden ayudarme para encontrar el problema por que no me entra la señal por el in de la pcb?
    todo esta ok, soldaduras, componentes y pistas de cobre de la pcb, he repetido dos veces el proyecto y las dos han dado el mismo problema.
    Gracias de antemano y saludos

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