Clue on How to produce Layouts from Schematics

[Zarrir]

I recently came across a nice tube amplifier project (12AX7 - 6N6). Seems to be a very easy to build amp and i have attached the schematics to this post. I have a question for the specialists: How do i go to produce a nice layout (like the ones on Hoffman amps) based on these schematics? Is there any software to help? If not, any clue on how to begin? Sorry if this has been covered before, i could not find anything in the archives.

[Joel]

I use a combo of existing similar designs (Hoffman, Sluckey, Ceriatone, Fender, Marshall, etc), and a pencil, paper and eraser.

[terminalgs]

I've never seen software that'll do it.


I draw layouts 1:1 scale on graph paper using pencil.  If I know I'm using a large component, I'll keep it handy and make sure it'll fit the area that I've draw for it (like a big electrolytic).  On the graph paper, outside of the area of the circuit board I'm designing, I'll draw the tube sockets and the pots and jacks.


I end up moving connections around on the board, trying to minimize eyelet (or turret) count, and following best practices for layouts and all the tried and true component arrangements you see on hoffman boards and the like.


Once the board is to my liking, and I've retraced the entire schematic to make sure nothing is left off the drawing, I'll make a photocopy/xerox copy.   Since the drawing is 1:1, I'll cut out the board and tape it to the real board.  At the drill press I'll drill all the eyelet holes as well as the mounting holes that I also drew on it.




While good schematic drafting follows rules of thumb that let the engineer or technician quickly understand how it works, the layout design has much differ priorities:   physical component sizes, cost of materials (eyelets, wire, etc),  physical dimensions, and of course performance related things noise-minimization, current flow, grounding best practices and proximity to other off-board components like transformers, tubes, pots, jacks, etc...

[tubenit]

A FREE and easy to use program for drawing schematics is ExpressSCH.  It's intuitive and there are 100's of editable drawn schematics and layouts here:      http://el34world.com/Forum/index.php?board=12.0

When I draw a new layout, I typically grab one that is kinda sorta quasi similar to what I am needing and then edit it.

The ExpressSCH program is here:   https://www.google.com/#q=expresssch

There is a "generic"  Hoffman style turret board template and a generic parallel turret board template here:

http://el34world.com/Forum/index.php?topic=14802.0

This program is NOT as sophisticated or nice as Hoffman or Sluckey's drawing program, but it is FREE and it's easy to use.

One can also look at Fender amp layouts.

With respect, Tubenit

[PRR]

Off-question... this does not look like a "guitar amp". The gain is low, the input network is funny. Input sensitivity is like 0.3V, whereas guitar amps aim for 0.05V-0.01V. And the A2 triode *may* be "too polite" for gitar (I dunno).

As a hi-fi-ish amp, OK, if obscure and unpromising. (6N6/6B5 was Triadyne's power bottle which did not infringe on the Power Pentode patents. It did not catch on. big image For ~~$37{!} you are as likely to get the boring metal version as the glass.)
Intro note: http://www.mif.pg.gda.pl/homepages/frank/sheets/201/6/6B5.pdf

Aside from a few details, the layout is same-as a Champ. Even the dual-triode connects nearly the same: the extra plate goes to a B+ just like the screen of a 6V6. (6B5 could replace a '42 power pentode directly, if you removed bias.) The NFB is the same as some middle Champs.

[kagliostro]

I confirm all that Tubenit says

I would like only to add a pair of further info

Doug and Steve use Visio as layout program and the results as you can see are very good, also I use Visio (an old 2007 version)

if you can, get one second hand and keep it, Visio is not very difficult to learn to use and really is full of useful features, libraries for tube layout can be found, if you need ask it

--

A program that can draw layout from schematics is Eagle, the function is called routing, but is a program used more for PCB than Turret or Eyelet Layout, I've Eagle but don't use it for tube amp layout, also Eagle show you the connections between components, but you must move them (the components) and place them on the board (the right place is your choice)

Franco

[jjasilli]

I don't think there's A Way to produce a layout.  To my mind there's 2 alternatives for point to point: the old fashioned "rat's nest" (my term), or a neat layout like Fender eyelet boards or Hoffman turrets.  Old fashioned rat's nest can use creative wiring shortcuts, but is hard to trace-out.  On boards, the components for each section of circuit are placed near one another in a logical fashion, lined up nice & neat.  Look at the layout diagrams from simpler amps like Champ, Princeton, etc.  Note the layout for the different circuits: Gain Stage, PS, Bias Supply.  These "lay down the law": conventions that are generally followed for physical layout on a board.


The drawing programs do not actually produce a layout for you.

[Zarrir]

All good ideas. I will first take a look at Visio then. For this specific amplifier, it seems like boards side by side are the way to go. PRR, yes, it is a Hi Fi amp design. Hahaha, "creative wiring shortcuts" is AWESOME! 

[goangling]

I have tried Smart Draw CI .   There is a free download, but it only gives you a limited number of launches, so if you do it all in one evening it is free.  I produced this in about an hour .. then my trial ran out before I got back to it. 

[PRR]

I note it says "125D" It should be "125DSE", but the -SE series (for SE operation with DC current) were not introduced in 2003.

As you know from tube data, nominal load is 7K, working load can be 5K or 10K with little change.

My experience with the 125ESE suggests that at these impedances you will be solid to 100Hz but short of inductance at lower frequency. The roughly 6dB of NFB will flatten the small-signal response to 50Hz or so, sure. On much music this will be fine. It may not give full authority on Jack Casady's bass lines; but then few *speakers* can do that with a mere 4+ Watts. Of course there are an infinite number of fatter costlier 5K SE OTs sold for antique triode worship.

[terminalgs]

Off-question... this does not look like a "guitar amp". The gain is low, the input network is funny. Input sensitivity is like 0.3V, whereas guitar amps aim for 0.05V-0.01V. And the A2 triode *may* be "too polite" for gitar (I dunno).

6.8K/3.3K resistors looks like it makes loads of NFB.  Plus not much B+, so not much VDC on the plates of preamps.  Seems like it'd fizz out like a little AC/DC amp with a 25LC  or a 50C5.  I can't imagine this being more than 3W.

[Willabe]

It may not give full authority on Jack Casady's bass lines.....

Now that's a bass player!     

Got to be in the top 5 of rock bass players.   

[PRR]

> 6.8K/3.3K resistors looks like it makes loads of NFB.

It's not a high-gain power tube. The 12AX7 isn't giving gain much over 25 with all that resistance in cathode. I forget my figurings, but I thought 2:1 or 3:1 NFB around this section. Get Damping Factor down to 0.5 or 0.3, which will make a "high damping" speaker flat enough it won't suck. THD will go down but with multi-tone input (any speech/music) the IMD will splatter all over. Much like many guitar amps, true.

> I can't imagine this being more than 3W.

You make me look it up. 6N6 makes

B+ -- Drive - Watts
250 - 19 ---- 2.5
300 - 21 ---- 4.0

So yeah, interpolated 3.25 Watts at the noted 275V. But the path to the whopping 4.0 Watts is clear.

Need 0.8V peak at V1b grid. I dunno why they didn't stop there. The first stage is 1/6 loss into gain of 25, say 4X total, 0.2Vpk 0.14Vrms input sensitivity. A bit hot for hi-fi (why there's a knob).

Ah, if you take the goofy attenuator off the front, input sensitivity is 0.024Vrms, exactly my "~~20mV" target for normal guitar. Gain pot should go between stages. First stage sure will want over 118V for hot guitars. My "too polite" comments could be refuted by reducing the NFB around the back, also gets the sensitivity up (lower Volts to overdrive). So it could be "a guitar amp" without big change.

That's still a fairly expensive and rare, and heater-hungry, tube for what's really just a 3/4-power Champ. That odd/obscure dual triode is hardly a 6V6, but may not be all so different.

Likewise, two ($36!!) tubes can make 10 Watts, even 18W if you dig in the 6B5 datasheet. But sucking as much heater power as a EL34 or 6550.

For more non-cheap fun: they tried to promote this concept for transformerless radios:
http://www.mif.pg.gda.pl/homepages/frank/sheets/201/2/25B5-25N6G.pdf
2 whole Watts at 9%THD with 110V supply! But max 180V (3.8W), needs bias at that point, and the 25xx type seems to be lower-Mu than the 6V types (against usual expectation). And no 25N6 at two major tube suppliers, so it's rare. www.vacuumtubes.net has 25N6G for $10.00, but may be "used, good".

[drgonzonm]

This forum provided a link to a vector based CAD program. It can read dwg dxf, and can also output such formats.  The name of the program is draftsight, it is a 2D drawing program.  You will need to register the program at 6 months and yearly after that.  It is a free download. 

You can create your own components. draw to scale.

I do not typically download pdf's, but it may have the capabilities to import pdf's. 

One of the features I like is the ability to rescale.  Lets say some one posts a layout in a picture.  You can resize the picture and overdraw the photographed board, soon you can have a drawing layout. 

It does a learning curve like most graphic programs. 

[Merlin]

Some options:
DIY layout creator; https://code.google.com/archive/p/diy-layout-creator/
Free vector drawing program liek Inkscape;
Paper (graph paper is handy) and pencil.

[Zarrir]

This forum provided a link to a vector based CAD program. It can read dwg dxf, and can also output such formats.  The name of the program is draftsight, it is a 2D drawing program.  You will need to register the program at 6 months and yearly after that.  It is a free download. 
 

Excellent! As a matter of fact, it can import PDF using a plugin (https://www.youtube.com/watch?v=yptcR9KJTRA) which is AWESOME!

[G._Hoffman]

I use KiCAD for all of my electronic design needs.  The learning curve is a bit steep, but it is a very capable program, and it allows me to layout all of my wire runs, at least in part.  It is, of course, designed for designing printed circuit boards, but it is easy to lay it out as a turret board, and think of the PCB traces as wires (or board lacing).  You would need to draw your own footprints for parts on turrets (or I could maybe be convinced to email you mine, which even have nice 3D renderings!), but again, it's not too hard to do.  There is basically no electronics project which is too complicated for KiCAD, hence the learning curve, but once you get used to it's quirks, it is a great program.  And there are some good tutorials for it out there as well.

On a side note, KiCAD is the electronic CAD package they use for everything at CERN!  They have largely taken over the development, and have done some very nice work on it.  This is one of the really great things about the program, though - it is an open source program, so it does not have any of the limitations you get with free and cheap versions of commercial software.  You can design any sized board, with as many layers as you want, and it is still free.  They do ask for donations if you are doing commercial work, but that's just fair.  For tube amps, I really like the many layer design tools, because I can set up a separate layer for each type of connection - two for heaters, one for cathodes, one for B+, one for plates, etc., and they can all be different colors, and they can cross each other without problems.  It is great for organizing your build. 


Gabriel

[Planobilly]

I downloaded expressSCH a few days ago. I had it up and running in a few minutes and found it very easy to use. There is a friend of mine who has a component file for things that are not in the program such a tubes. He has not got around to sending it to me yet but I think I will have it by the middle of next week. I will be glad to pass them around to anyone who needs them.

The program is good for drawing schematics but not layout drawings. For me, none of the vector based drawing programs I have tried to use are simple to learn. I have some software for CNC machining but it is not at all easy to use, at least for me. In fact, I have a CNC mill but for what Hoffman charges to make a custom turret board I buy them from him. G code drives me nuts!!...lol

I find it much less trouble to do a drawing by hand on a drafting table. Learning Visio or other programs requires some learning curve. If you like diddling around with software that can be it's own reward. If you need the layout done in a hurry, well, pencil and paper has done millions of drawings.

Some of this software is like speaking a foreign language, if you don't use it a lot you forget how. Well...at least for me.

Cheers,

Billy 

[John]

You can use SCH to make components for layout, sized and scaled. I use for board templates and everything.

[kagliostro]

This is a free option for a simple Layout Creator

http://diy-fever.com/software/diylc/

the program can has 3 options, Stripboard, Perforboard, PCB

you can use Perforboard option for Turret or Eyelet boards

Franco

[Zarrir]

This is a free option for a simple Layout Creator


the program can has 3 options, Stripboard, Perforboard, PCB

you can use Perforboard option for Turret or Eyelet boards

Franco

Awesome, Franco!  So easy to use! Thanks