PCB Layout

[dsavitsk]

Take 3

I think I managed to do most of the suggestions. I am not sure if this is exactly what Tangent meant w/r/t/ R6. I am not sure I like it as it is, esp since there is a 90 degree angle, so I need to fool with that a bit more.

Other changes are that I moved the pot and C1R to the left to get them to line up better. Also, the B+ traces were changed. One problem there is that the center pin is now live. Since a 9 pin socket would simply not connect to that pad, I am not sure if this is a problem or not. This could be fixed with a thinner trace. Otherwise, I tried to keep things clear of the tube pins in general.

One thing I don't like is that on one side,the grid goes to R2 then to R3, and on the other side it goes to R3 then R2. I don't believe that this matters electrically, but aesthetically I don't like it. Changing it means making a trace longer than it needs to be (though only by a fraction of an inch), so I am not sure which is better.

-d

 

[guzzler]

Quote:

One problem there is that the center pin is now live. Since a 9 pin socket would simply not connect to that pad, I am not sure if this is a problem or not. This could be fixed with a thinner trace. Otherwise, I tried to keep things clear of the tube pins in general.

Perfect example of not bothering with a 45 degree angle. If you move the turn just above the centre pin to the right slightly, you'll avoid the pin, and maintain the same routing, without having to change the track width.

Quote:

One thing I don't like is that on one side,the grid goes to R2 then to R3, and on the other side it goes to R3 then R2. I don't believe that this matters electrically, but aesthetically I don't like it. Changing it means making a trace longer than it needs to be (though only by a fraction of an inch), so I am not sure which is better.

Doesn't matter at all (electrically), and it's never going to be completely symmetric

Nice job

 

[jcx]

heater traces should be as close together as possible to reduce magnetic field radiating from the large loop area - these are probably the largest current traces on the board, regulated dc i hope

 

[tangent]

Quote:

Originally Posted by Born2bwire what is your heuristic for choosing the amount of chamfer for a bend in the microstrip?

My heuristic in that situation is "call a real engineer". I just play one on the Net.

If I had to find an answer, I'd turn first to Howard Johnson's books. But that's just a wild guess, based on limited experience.

 

[Voodoochile]

Quote:

Originally Posted by dsavitsk This is as much about learning to design PCBs as anything else.

So is building it up on terminal boards first. It's a fundamental part of the process of designing a layout and routing, especially if you are new at it.

Your layout does look good, by the way.

 

[Garbz]

I still think that the ground plane should fill the area under the tube where B+ used to be, but do observe the clearence jcx mentioned.

 

[dsavitsk]

Quote:

Originally Posted by Voodoochile So is building it up on terminal boards first. It's a fundamental part of the process of designing a layout and routing, especially if you are new at it.

I have done a few point to point projects, and I did this one with pencil and paper about 8 different ways until I hit on something that seemed promising.

Quote:

Your layout does look good, by the way.

Thanks.


I was going to call this one the last I was going to do until seeing Garbz's note about the ground plane.

I increased the size of the pads where hookup wires and caps connect -- I am tired of TCSS not fitting into boards, particularly since I have some Kimber Kaps around that use TCSS for leads -- I also increased the spacing between pads and the ground plane due to the possible high voltages. I moved the heater traces back together, which I think looks better anyway. I also moved a few other traces, but nothing major. So, with the exception of the possible extension of the ground plane, I think this is done for now.

I've no plans to actually manufacture this anytime soon, but of anyone wants the board files, I'll put them online before too long. Thanks for all the help.

-d

 

[dsavitsk]

Here it is with the bottom layer as a full ground plane, and all traces moved up to the top.

 

[skyskraper]

what i would do is flip R1L around just to make that little area of the board a little less clustered, then you could wiggle the other two traces around a bit to give them a bit more space.

it's looking better and better each revision

 

[dsavitsk]

Quote:

Originally Posted by skyskraper what i would do is flip R1L around just to make that little area of the board a little less clustered

That's a good suggestion. I kept looking at it, and my first thought was that it wouldn't really do much good, but once I did it I saw that I could place the trace on the other side of R1L's ground pad.

I know I said I was done a few revisions ago, but I just can't leave well enough alone. I also added some mounting holes (the pot shaft is the one for the front.)

 

[MisterX]

Got to move the C1R cap back a bit to clear the front panel but otherwise I want one.

Nice job!

 

[skyskraper]

cool

mounting it in a case, will there be enough space for C1R without being angled? i would maybe move the resistors towards the tube socket just a bit to give it a bit more space.

maybe someone with a bit more experience with manufacturing may be able to chime in, but the top pads for the C1's seem to be very close to the edge of the board and may create issues in manufacturing. well id be curious to know if they do create issues anyway.

 

[dsavitsk]

Quote:

Originally Posted by MisterX Got to move the C1R cap back a bit to clear the front panel

Oh man ... that's really stupid. Um ... what I was intending is that you would attach this to a brace in the back of a case and a shaft extension would then reach forward ... yeah.

 

[dsavitsk]

Quote:

Originally Posted by skyskraper the top pads for the C1's seem to be very close to the edge of the board and may create issues in manufacturing.

I think you're looking at the silk screen (which doesn't get printedon the cheap boards.) The pads all around are the same distance from the edge. Any closer and the program throws up a flag, but it is letting these through.

 

[skyskraper]

oh cool, wasnt sure if the software did that

is there a particular reason for that exact board size? making it a little bit bigger would give room to play around a bit more with the parts/traces and give space for mounting holes at the front of the board.