How to create/design a layout from a schematic?

Discussion in 'Shock Brother's DIY Amps' started by joel_ostrom, Mar 28, 2013.

  1. joel_ostrom

    joel_ostrom Tele-Afflicted

    Posts:
    1,135
    Joined:
    Sep 11, 2006
    Location:
    Calgary, AB
    I'd like to build a clone of my Fender Blues Jr., but all I can locate online is a schematic. Some amps have specific layouts that really help with building an amp from scratch, but this one has been hard to find.

    Is there some good methods to designing a layout just from a schematic alone?
    Anybody ever done this before?

    Thanks,
    Joel
     
  2. hackworth1

    hackworth1 Friend of Leo's Vendor Member

    Posts:
    3,578
    Joined:
    Oct 11, 2009
    Location:
    Volusia County, Florida
    First, you must understand the schematic. It's codes support a basic formula that becomes clear through study and understanding of the fundamentals of tube circuit operation.

    Seasoned builders do exactly as you describe. They study a schematic and create a layout from it.

    It is fairly easy for the beginner to follow a layout. It would be difficult for most beginners to create a layout based upon a schematic.

    Without understanding form and function, a schematic is an enigma.
     
  3. joel_ostrom

    joel_ostrom Tele-Afflicted

    Posts:
    1,135
    Joined:
    Sep 11, 2006
    Location:
    Calgary, AB
    What's the best place to start if I want to learn about reading schematics and then (eventually) translate them into a layout for actually building the circuit?
     
  4. hackworth1

    hackworth1 Friend of Leo's Vendor Member

    Posts:
    3,578
    Joined:
    Oct 11, 2009
    Location:
    Volusia County, Florida
  5. jefrs

    jefrs Doctor of Teleocity

    Posts:
    13,310
    Joined:
    Nov 20, 2007
    Location:
    Newbury, England
    This is an art form and everyone does it differently.
    Suggested reading Morgan Jones "Building Valve Amplifiers".

    If you are cloning the PCB then one aid to reverse-engineer it is to photograph the board with a powerful back light to obtain an "X-ray" image of both sides of it at once. But from memory the BJr board is rather busy.

    Another consideration is that certain wires and components have to be kept separated to avoid cross-talk interference. And keep wires/connections short whilst observing that 10kV can jump 1cm in dry air (HT/B+ can arc small gaps). This is important even if you are rebuilding P2P.
     
  6. printer2

    printer2 Poster Extraordinaire

    Posts:
    6,365
    Joined:
    May 24, 2010
    Location:
    Canada
    I need to build this guy one day, tried to make it simple so someone new to amps can relate the schematic to the layout.

    [​IMG]

    [​IMG]

    Now the next step would be to take the wires going to the off board devices and orient them to where they would be in real life, As an example two of the triodes would be in a tube like a 12AX7, you would draw the tube and run the wires to the proper pins. Now as jefrs mentioned, you could run into problems with feedback, noise, all because the wires and parts are not the only part of the circuit. The spaces around the wires set up electrical and magnetic fields that can interact with each other. Wire routing can make or break an amp.

    Now looking at the schematic of the Jr, it looks like an 18W with an added gain stage to make up for some of the loss associated with the reverb. Offhand, I would say grab a reverb Deluxe board, move the tone stack after the second triode. Might as well go with the tube reverb, it is on the board and you will not have to bother with mixing SS and tubes. Other than that use the part values for the Jr. instead of the Deluxe. Well, keep the reverb 4.7M 10pF parts.
     
  7. joel_ostrom

    joel_ostrom Tele-Afflicted

    Posts:
    1,135
    Joined:
    Sep 11, 2006
    Location:
    Calgary, AB
    Wow, thanks for the images man. I'll study them and try to figure out how the transformation from Schematic to Layout works. How did you come up with this layout design?

    I have a lot to learn about building amps, but i have some books i'm reading up on. It sounds like a fun hobby, i hope to learn as much as i can.

    Cheers!
     
  8. joel_ostrom

    joel_ostrom Tele-Afflicted

    Posts:
    1,135
    Joined:
    Sep 11, 2006
    Location:
    Calgary, AB
    Done! I ordered myself a copy on Amazon tonight. Looking forward to it!:D
     
  9. LeroyBlues

    LeroyBlues Tele-Holic

    Posts:
    928
    Joined:
    Apr 23, 2008
    Location:
    Michigan
  10. 6942

    6942 Poster Extraordinaire

    Age:
    66
    Posts:
    6,333
    Joined:
    Apr 15, 2006
    Location:
    Santa Fe, NM
    I'll draw the schematic out on a large piece of paper first.
    That way, I can make notations on it, as far as any changes I MIGHT want to make.
    I like using turret boards for my point-to-point wiring.
    FWIW....I usually buy my turret board from Angela Instruments in Maryland on-line (NO affiliation).

    Good luck!!
    Steve
     
  11. tony hunt

    tony hunt Tele-Meister

    Posts:
    469
    Joined:
    Aug 22, 2012
    Location:
    230V / 50Hz / GMT +1
    Here is my 2c:

    I think you need to look at several circuits to get a conceptual grasp of the stages in a schematic. Like a block diagram, try to get an eye for it. That knowledge is important to keep an overview and prevent you from being lost in the woods.
    Right now I am trouble shooting a really complex amp and I need to break it down into stages. I'm trying to say that it is not just a beginner thing to do.

    A good layout often follows the "block diagram" concept very closely, not running backwards and forwards but keeping signal distances as short as possible.

    The Blues Jr is a tough first choice. Something like the circuit from Printer2 would be a good starter. Some of the early simple circuits sound amazing, like a 5C1. It seems to me all the bells and whistles came to amps over time help sell them. Much like the extras they add to mobile phones these days. Often they just get in the way of the job at hand and make life complicated.

    Best, tony
     
  12. Mr Ridesglide

    Mr Ridesglide Tele-Afflicted Ad Free Member

    Posts:
    1,919
    Joined:
    Dec 11, 2009
    Location:
    Bloomington, MN
    My son has a Blues Jr. I built a 5e3 kit from Boothill Amps. He prefers the 5e3. About the same output with a much richer tone. No reverb, but you won't miss it much. I never cared for the reverb on the Jr anyway. I'd start there.
     
  13. jhundt

    jhundt Doctor of Teleocity

    Age:
    65
    Posts:
    11,642
    Joined:
    Mar 23, 2003
    Location:
    Netherlands
    @printer2 - very nice drawings! can you tell me what program you use to make them so clear? And can you describe the inspiration behind your design? It looks a bit 6G2-ish with some intriguing changes - such as that big grid-stopper on the phase inverter. I have been thinking about trying one of those in my PR.

    also - I think the schematic does not show the ground at the bridge rectifier; and the layout shows a cap across the rectifier that I can't see on the schematic. But I am a very poor reader of schematics, so perhaps I am missing something.
     
  14. printer2

    printer2 Poster Extraordinaire

    Posts:
    6,365
    Joined:
    May 24, 2010
    Location:
    Canada
    Right on all counts. It is a 6G2, tried the grid stopper when I breadboarded a simple amp and liked it. You are also right on the lack of a ground on the bridge. That is the problem with cut and pasting, too easy to change things and easy to miss a thing or two, originally it was drawn as a voltage doubler.

    The programs I used was TinyCAD for the schematic, DIY Layout Creator for the layout. Layout Creator I have mixed feelings about, not the most friendly program, would hate to do anything complicated with it. TinyCad, I got used to it. But since they are both free...

    Oh yeah, the cap across the transformer, just a bit of noise filtering, spur of the moment addition.
     
  15. jhundt

    jhundt Doctor of Teleocity

    Age:
    65
    Posts:
    11,642
    Joined:
    Mar 23, 2003
    Location:
    Netherlands
    thanks for the info. I know what you mean about cut-and-paste. I have been working on a layout for an amp, I am using Hoffman's schematics and layouts as a starting point. I am designing a top-mounted PC board (as used by Ampeg many years ago). But I sit in front of the computer for hours and hours, playing with MS Paint. I have convinced myself that it is a learning curve. My wife thinks I'm just horsing around....
     
  16. printer2

    printer2 Poster Extraordinaire

    Posts:
    6,365
    Joined:
    May 24, 2010
    Location:
    Canada
    Horsing around? Shows you how much she knows. :p

    Speaking of paint and layouts, I took a 5E3 layout from Fender and modified it in Photoshop thinking it would be quick and easy. Hah! In the end I got this.

    [​IMG]

    Nope, nothing is quick and easy the first time around. I said I was going to finish building that amp this week, good thing I am not a betting man. Got guitar building on the brain, well at least building tools for guitar building.
     
  17. Keyser Soze

    Keyser Soze Tele-Holic

    Posts:
    948
    Joined:
    Oct 13, 2009
    Location:
    Johnson City, TN
    Personally I find even with a bit of understanding schematics are still quite the enigma. And the more you delve into the details the more complex it gets.

    To the OP:

    Practically speaking there is nothing wrong with 'borrowing' as much as possible from similar amplifiers. In fact using an already proven concept is the most reliable method for achieving a successful build.

    And fortunately there is no one absolute way to do it. The key is to do whatever you do cleanly and logically. In general the lower the gain and/or more simple the circuit the less sensitive it is to layout related issues.

    As far as I'm concerned drawing a layout is a lot like creative writing - get something down on paper, explore it critically, then begin making your corrections and alterations. Lather, rinse, repeat.

    Except in the case of an amp eventually you will build the layout. Once built, if you are 'lucky' your amp will function perfectly and you won't learn anything additional.

    If you are like me you'll have some issues (noise, feedback, etc) and then you'll learn a thing or two that you didn't know about proper layouts...
     
  18. joel_ostrom

    joel_ostrom Tele-Afflicted

    Posts:
    1,135
    Joined:
    Sep 11, 2006
    Location:
    Calgary, AB
    Wise words. Thanks for the advice. I'm very interested to learn. Starting simple seems like the best place to start. I'm sure there's an ever abundant amount to learn, but I feel like i've got lots of great guys here to offer advice if I need it.

    Cheers!
     
  19. 6942

    6942 Poster Extraordinaire

    Age:
    66
    Posts:
    6,333
    Joined:
    Apr 15, 2006
    Location:
    Santa Fe, NM
    I always double check EVERYTHING from my layout page, BEFORE firing up an amp.
    Nine times out of ten, I'll find a (groan) wiring error...................................
     
  20. Keyser Soze

    Keyser Soze Tele-Holic

    Posts:
    948
    Joined:
    Oct 13, 2009
    Location:
    Johnson City, TN
    Absolutely. I make photocopies of both schematic and layout, then go over them both with highlighter, marking off corresponding connections to verify the entire circuit.
     
IMPORTANT: Treat everyone here with respect, no matter how difficult!
No sex, drug, political, religion or hate discussion permitted here.


  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.