ampage Tube Amps / Music Electronics	For current discussions, please visit Music Electronics Forum.

ampage archive

Vintage threads from the first ten years

Re: Construction techniques Questions

7/20/2000 6:21 AM
Plexibreath	Re: Construction techniques Questions >>>>> I do something similar, except I do the board layout on a PCB CAD program. <<<<< Absolutely! I'm a PCB Designer for my day job, but even for a hand wired amp I use my CAD layout tool, PADS-PowerPCB, to place the components and plan the wiring. I built a separate library of components with eyelets for my tube amp projects. I spend most of the project's time tweaking the placement in CAD to perfection. I use eyelets into 1/8' thick fiberglass by 6" wide, this gives me a wide area to place the tube sockets close to the input jacks and pots. I cut 1" circles into the fiberglass for the tube socket pins to poke through, I then run short wires from the pins to eyelets close to the tube socket, it allows me to place components close to the tube sockets, (almost as if it were a real PCB with PCB mounted sockets though they are actualy chassis mounted), this keeps my signal wires very short and makes it easy to change tube sockets. I plan the wire routing while I'm placing the components. I would use a printed circuit board but I can't afford the fab costs to get one built right, (plated through holes, 4 oz. copper, .125 thick), so for now I use eyelets and hand wiring. Also, because most of the floor of the chassis is covered by the board, I have holes in the fiberglass to easily access the mounting screws for my transformers, wires from the transformers go through the chassis, through the fiberglass and directly to eyelets, separate wires go off from those eyelets to where needed, this makes it real easy to replace transformers, (which I do a lot for experimentation). Using PADS is overkill, in my case it's the software I have, you just need something where you can build components you can copy and move around and add connections so you can plan where your wires will go, very basic, I'm sure something appropriate is available as shareware somewhere. Planning it all out ahead of time on a CAD tool will help reduce frustrating experiences like parasitic oscillations, phase cancallation, AC hum, etc.. Have fun with your project, please let us know what method you used. John Kelley Brown

7/20/2000 6:21 AM

Plexibreath

Re: Construction techniques Questions

>>>>>
I do something similar, except I do the board layout on a PCB CAD program.
<<<<<

Absolutely! I'm a PCB Designer for my day job, but even for a hand wired amp I use my CAD layout tool, PADS-PowerPCB, to place the components and plan the wiring. I built a separate library of components with eyelets for my tube amp projects. I spend most of the project's time tweaking the placement in CAD to perfection. I use eyelets into 1/8' thick fiberglass by 6" wide, this gives me a wide area to place the tube sockets close to the input jacks and pots. I cut 1" circles into the fiberglass for the tube socket pins to poke through, I then run short wires from the pins to eyelets close to the tube socket, it allows me to place components close to the tube sockets, (almost as if it were a real PCB with PCB mounted sockets though they are actualy chassis mounted), this keeps my signal wires very short and makes it easy to change tube sockets. I plan the wire routing while I'm placing the components. I would use a printed circuit board but I can't afford the fab costs to get one built right, (plated through holes, 4 oz. copper, .125 thick), so for now I use eyelets and hand wiring.
Also, because most of the floor of the chassis is covered by the board, I have holes in the fiberglass to easily access the mounting screws for my transformers, wires from the transformers go through the chassis, through the fiberglass and directly to eyelets, separate wires go off from those eyelets to where needed, this makes it real easy to replace transformers, (which I do a lot for experimentation).

Using PADS is overkill, in my case it's the software I have, you just need something where you can build components you can copy and move around and add connections so you can plan where your wires will go, very basic, I'm sure something appropriate is available as shareware somewhere. Planning it all out ahead of time on a CAD tool will help reduce frustrating experiences like parasitic oscillations, phase cancallation, AC hum, etc..

Have fun with your project, please let us know what method you used.

John Kelley Brown

7/20/2000 5:31 PM
Plexibreath	One other thing. What ever method you use, eyelets, pads, turrets, space them wide enough apart where you can change value or rating of the components easily. Where you would use half watt resistors, plan for 2 watt in case you change your mind in the future. Where I might put a small packaged metalized .022 coupling cap, I'll space the eyelets wide enough apart to allow those large .1uf blue vintage Fender caps and allow for wide enough body to go with a paper-in-oil cap if I so choose.

7/20/2000 5:31 PM

Plexibreath

One other thing.
What ever method you use, eyelets, pads, turrets, space them wide enough apart where you can change value or rating of the components easily. Where you would use half watt resistors, plan for 2 watt in case you change your mind in the future. Where I might put a small packaged metalized .022 coupling cap, I'll space the eyelets wide enough apart to allow those large .1uf blue vintage Fender caps and allow for wide enough body to go with a paper-in-oil cap if I so choose.

7/21/2000 5:32 AM
Casey4s	RG & Plexibreath: I have never tried a cad program. I do all my chassis layouts and circuit board layouts the old fashioned way (cause I'm an old fart I guess) on a drafring table with a drafting machine I would really like to try CAD, but my budget is limited and HD space on my "Cheesy" PC is a premium. Could some body recommend a cheap, small program to do some of this stuff with? I do not intend to make PCB's but the basic layouts hard wired like Plexibreath does might make things more efficient. My "antique" drawing method works for me but there is always room for improvement... Thanx...Casey4s

7/21/2000 5:32 AM

Casey4s

RG & Plexibreath:

I have never tried a cad program. I do all my chassis layouts and circuit board layouts the old fashioned way (cause I'm an old fart I guess) on a drafring table with a drafting machine

I would really like to try CAD, but my budget is limited and HD space on my "Cheesy" PC is a premium. Could some body recommend a cheap, small program to do some of this stuff with? I do not intend to make PCB's but the basic layouts hard wired like Plexibreath does might make things more efficient.
My "antique" drawing method works for me but there is always room for improvement...

Thanx...Casey4s

7/21/2000 6:37 AM
Plexibreath	Casey4s, A couple years ago I was at an electronic supply store, I don't even remember the name of it. Anyway, at the front counter they had a bare bones CAD software package for people that just wanted to etch their own simple 1 layer PCBs, I seem to recall it costs under $20, I don't remember the name of that software package either. The point is though, the software is out there, try doing a Yahoo search for shareware PCB layout software. In the meanwhile, I'll keep my eyes open for it as well. For this kind of thing, I'm sure that even a simple paint program that comes with your computer would allow you to make component shapes, then copy and paste them around on the board. In the old days of pencil and tape layout, mockups of components you could move around to plan your layout were called "puppets". Doing this work on your computer saves your puppets from getting torn and keeps the coffee off the vellum, any time you want to recreate the board, just print out the file, lay it over your board material, (whatever that might be), and start drilling holes for you eyelets or turrets. If you have dialed in a small section of circuitry, you can reuse that section by pasting it into an all new amp design, saving you a lot of work. John Kelley Brown

7/21/2000 6:37 AM

Plexibreath

Casey4s,

A couple years ago I was at an electronic supply store, I don't even remember the name of it. Anyway, at the front counter they had a bare bones CAD software package for people that just wanted to etch their own simple 1 layer PCBs, I seem to recall it costs under $20, I don't remember the name of that software package either. The point is though, the software is out there, try doing a Yahoo search for shareware PCB layout software. In the meanwhile, I'll keep my eyes open for it as well.

For this kind of thing, I'm sure that even a simple paint program that comes with your computer would allow you to make component shapes, then copy and paste them around on the board. In the old days of pencil and tape layout, mockups of components you could move around to plan your layout were called "puppets". Doing this work on your computer saves your puppets from getting torn and keeps the coffee off the vellum, any time you want to recreate the board, just print out the file, lay it over your board material, (whatever that might be), and start drilling holes for you eyelets or turrets. If you have dialed in a small section of circuitry, you can reuse that section by pasting it into an all new amp design, saving you a lot of work.

John Kelley Brown

7/21/2000 7:30 AM
Casey4s	John K Brown, Thanks for the fast reply, I'll search Google and see what I can find. Back in '67 I was a draftsman for an engineering company that did Govt contract work. We used the "Puppet" thingies too, but we called them something else(?) (Then "I" got drafted ) I draw everythig out full scale when I build anything and use copies for templates.It does make for less errors when putting the thing together. But I would like to give a cad program a shot. Thanks, casey4s

7/21/2000 7:30 AM

Casey4s

John K Brown,

Thanks for the fast reply, I'll search Google and see what I can find.

Back in '67 I was a draftsman for an engineering company that did Govt contract work. We used the "Puppet" thingies too, but we called them something else(?) (Then "I" got drafted

)

I draw everythig out full scale when I build anything and use copies for templates.It does make for less errors when putting the thing together.

But I would like to give a cad program a shot.

Thanks,
casey4s

7/21/2000 5:40 PM
Eric H	Casey, I'd be willing to bet the program john mentioned was "Winboard" Do a search at Google, they have a demo. -Eric

7/22/2000 2:23 AM
Casey4s	Thanks Eric, I'll check it out. Casey4s

Page 2 of 8