Designing my first largeish PCB

[mth5044]

Hello all.

I downloaded the DIY layout creator and have been messing around with it. I'm going to attempt to make my own PCB layout of the Triangle BMP. By attempt, I mean I already did and its really big. It would be about 4"x1.5", which is ridiculous. Here is a rendering of it.



It is based of the triangle schem from GGG  http://www.generalguitargadgets.com/pdf/ggg_bmp_tri_sc.pdf

A few thoughts I have about making it smaller (length wise) would be

1) instead of having a space between a lot of the pads, have them right next to each other. I'm not new to soldering, so I'm keen to avoiding solder bridges, but I don't know how 'close' close is. Is that what is done when you guys make pcbs?

2) Do resistors need three spaces (if I may call them that) between pads and caps (non electro) need 2? Or do resistors need only 2? I know they can be one, but I like to have mine flush against the pcb instead of sticking up.

I want to keep enough room in there for some kind of socket for the transistors, so that is why there is a little space around each of them. Making sure the PCB corresponds to schematic would be a plus, but that can be saved for another time, another thread :p

Thanks!

[Nitefly182]

I have no PCB design experience but it looks like you have a lot of air between components that just doesn't need to be there, especially if youre using ceramic disc caps like the original pedals. I think you could probably at least halve the distance between all those resistors and caps and still have plenty of room to work.

[bumblebee]

The first clipping stage doesnt connect to the second by the looks of it. And the first stage input should go into the base. Your definitely missing some traces between stages.

[davent]

Hello,

I'm not familiar with DIY Creator but usually the spacing of components is based oon a 0.1x0.1 inch grid (2.54x2.54mm).  The transistor pad spacing here is probably based on that spacing and there's no reason the spacing between resistor pads and cap pads can't be that close as well. Doing that alone will shrink your board considerably.

Have fun, laying out PCB's is one of my favourite parts of doing a build. I've got dozens of layouts that have never made it past that stage.

dave

[R.G.]

I think you would really like reading "PCB Layout for Musical Effects", my book on how *exactly* to do what you're trying to do. It's available through Small Bear.

[mth5044]

Thanks everybody. I am definitly missing some traces, probably due to my hasty put together. I am putting together another layout that is similar but without the spaces.

RG- I will check out that book next time I order from small bear, or atleast next time I find myself some cash.

Thanks again everyone, when I get the next version done, I'll put it up here and see what you all think then

[mth5044]

With great haste comes great mistakes? Surely someone said that. Well here it is, 2 inches shorter.



eye candy    I'm sure its like looking at a backed up septic tank for some of you. I kind of like it. Not as small as JD Sleeps PCB, but it's mine.

Comments, complaints? Should I be doing something different? I don't want to pm John Lyons just to have a faulty pcb 

Oh those extra bits on the bottom right are for grounds. I've seen several PCBs like that, so I thought what the hell.

Thanks!

[ForcedFire]

I prefer to set the trace widths to 10 rather than 5. Also the resistors only need to occupy 4 pads, so just 2 in between, I think you have 3. Definitely improving.

[davent]

With great haste comes great mistakes? Surely someone said that. Well here it is, 2 inches shorter.



eye candy    I'm sure its like looking at a backed up septic tank for some of you. I kind of like it. Not as small as JD Sleeps PCB, but it's mine.

Comments, complaints? Should I be doing something different? I don't want to pm John Lyons just to have a faulty pcb 

Oh those extra bits on the bottom right are for grounds. I've seen several PCBs like that, so I thought what the hell.

Thanks!

Hello, When I've got to the point where I think the layout is pretty good I print it out and "load" the board on a piece of styrofoam. That is I stick the leads of the components through the pad holes on the printout into the styrofoam. Seeing the board in three dimensions and with the actual components helps me see problems i'd otherwise have overlooked.

I would think you can make your 1/4w resistors and diodes smaller in that it looks like the pads for a resistor or diode are 0.4" apart you could make them 0.3" apart and save a bit more space again.

dave

P.S. Mr. Keen's book is on my Christmas wish list. Hope Santa knows how to get in touch with the Small Bear.

[John Lyons]

+1 for wider traces, easier to etch, more copper is good 
For that matter, bigger pads are much nicer to works with as well...

john

[mth5044]

Forcedfire - thanks for the comment. I looked through my layout creator (DIY Layout Creator I believe is what it's called) and I can't seem to find a way to change the width. Maybe it's time to upgrade? Any recomendations (keeping in mind I can't afford to by anything atm).

davent - that's a really cool idea. I'm definitly going to try that with this build, if I can find some styrofoam 

John - are you saying that I should increase the size of my traces and pads, or that they are at a good size and any smaller would be worse? Like I said above, I can't seem to change any of those things in my current program. I made a PCB with three wicked switches on this program that you printed (which I got a few days ago, looks good  ) and the pads/traces look to be an OK size.

Thanks for all the feedback.

[bumblebee]

With great haste comes great mistakes? Surely someone said that. Well here it is, 2 inches shorter.



eye candy    I'm sure its like looking at a backed up septic tank for some of you. I kind of like it. Not as small as JD Sleeps PCB, but it's mine.

Comments, complaints? Should I be doing something different? I don't want to pm John Lyons just to have a faulty pcb 

Oh those extra bits on the bottom right are for grounds. I've seen several PCBs like that, so I thought what the hell.

Thanks!

The resistors, diodes and caps don't need that much space either, you can shorten the leads on these components. I do resistors/diodes/caps 3 holes long, electros 2. Do that to that layout and it will be significantly shorter from top to bottom.

[mth5044]

Thanks for the info, but I think I'm going to keep it set up this way (spacing wise). I've been messing around with sizes on perfboard and I like the way that resistors fit in with three 'holes' between the pads. The caps are a bit of a stretch, but it's nothing I feel like doing the whole thing over for again. I will keep this in mind on my next layout.

RG - your book is now on my christmas list 

[Ice-9]

Thats looking great, and improving with each new design, the thing to keep in mind is tracks and components can be very close to each other but when hand drilling the pcb its nice to have the component pads a nice size so as to leave a nice bit o copper to solder to (if the pad is small its easy to break the track while drilling) . So wherever you have clearance around the pads make the pad a bit bigger.

What method are you going to use to etch the board. example if using laser printer and cloths iron then the biggest copper area the better for the tracks, but if your going to use photoresist board and uv light then you can have gaps very small between tracks (about 0.33mm or less)

things have changed so much from the days i remember rubbing lettraset onto pcbs for etching

[mth5044]

Thanks for the compliments 

I don't intend on making these PCBs myself, I was going to outsource to someone else. I live in an apt and don't have access to some of the stuff needed to make a pcb. One day I'll try to get into it, but I'd rather pay someone a few bucks to get a good quailty pcb done instead of trial and error my way through.

As for the pad sizes, I guess I could just go in with photoshop or paint and make them bigger. Thanks for the advice.

[mth5044]

So, I came back to this after letting it go for a bit. I worked on it some more and got it to be around 2" (from the first 5 incher  ), enough to fit into the 125B horizontally.



You can see there are a lot of empty pads. The ones on the bottom are for grounds for the power and input jacks and whatever else needs to be done. The ones on the right are for a tone switch which can be seen in this next pic



Can switch between the classic mid scoop, flat mids and boosted mids. I don't really like having the tone pot all spread out, but... meh.

And the PCB just for kicks



Thanks for all your help! It is strangely (although frustratingly) fun. If anyone wants to give it a look over for any problems, go right for it, although it's not really necessary. I'll find the problem eventually 

Did it from the GGG schem http://www.generalguitargadgets.com/pdf/ggg_bmp_tri_sc.pdf

Thanks everybody, you all are the best 

[Cliff Schecht]

So I'm guessing this software can't do ground planes..

[mth5044]

So I'm guessing this software can't do ground planes..

I dont know exactly what this means. Are ya talking about the large copper 'pool' like areas that I assume are ground? I don't understand what the point of them is

[Cliff Schecht]

So I'm guessing this software can't do ground planes..

I dont know exactly what this means. Are ya talking about the large copper 'pool' like areas that I assume are ground? I don't understand what the point of them is

Yes, it's the copper "pool" areas. They serve a few purposes, the most important one being that it gives you a strong ground that keeps everything referenced to the same potential (0 V). Thin grounds have a tendency to build up potential between point A and point B (let's say these points are 4 inches apart), making it so that the part at point A isn't at the same GND potential as point B. Return currents can, over these long and resistive ground runs, turn into an actual voltage that becomes noise in your circuit. Having a large ground plane makes it to where all grounds return to the same point and helps to prevents this build-up of voltage in your grounds, hence giving you lower noise and superior performance. It's also important to keep digital and analog grounds separate, otherwise the digital switching currents can show up in your analog signals and cause bleedthrough (LFO ticking, for example) as well as cross modulation (when your signal mixes with said LFO bleedthrough).

[mth5044]

Thanks for all the info.

I'm using DIY Layout Creator. I'm trying to look for something to make these ground plane. I found a way to increase the trace size, but that doesnt really help.

Hmmm