12AU7 PCB Starving Student Hybrid Amp - zammykoo Build Log

Nice.

Which etching technique did you employ?

Very nice board there.

Hey! Can I use your PCB design too? I'm doing a project in school and I wanted to etch a board with CnC the drill it. I was about to post for something I could put into MasterCAM but it looks like I found it! Can you send me a PM or post up your design sheet so I can take it learn from it then etch a PCB for class?

Thanks!!!

Nice! Copper looks thick and neat.. what method did you use for etching?

Try some of the advice here for your next etch and you might

get a better ground plane.

Otherwise, good job for a first try at a double sided board!

EDIT: Ah ... I see what you're asking.  On the manufactured PCB, one of the leads of each capacitor is soldered to a pad that's connected to the ground plane, where the ground plane forms the negative connection to the entire amp.  Maybe what we're missing here is the fact that manufactured PCB's have through-plated holes and when you solder on the backside, that counts as soldering on the front side, too.

Looks like a nice job with the PCB's, by the way.  They almost look like one of the non-silk-screened prototypes that Dsavitsk ran.

EDIT: If you can't run additional traces on the top side, maybe you need some make-shift vias by soldering additional small holes that will allow a jumper connection through to the ground plane?  I don't know - maybe someone who's had some more experience etching their own has some better ideas.

Quote:

Originally Posted by zammykoo 

Tom, thanks for chiming in.

 

I think you've answered my question about the manufactured pcb holes being connected on both sides... and since my double sided board holes do not connect from front to back, I'll have to drill additional holes next to the cap ground holes and bend the leads up back through to the ground plane to be able to solder the points.

 

Any other suggestions for a quick solution?

It's probably a kludge in either case, but quality electrolytics have a rubber pad on the bottom.  This would allow you to bend the ground lead out at a 90 degree angle, parallel to the ground plane, and solder it directly.  The electrolytic can still be flush to the PCB when you do this.  Look at one of the electrolytics with a rubber pad and you'll see what I mean.  Note that you may still have a bit of difficulty with this, because manufactured PCB's use "relieving" at the ground pads, where the metal is only connecting at four tiny points on the pad circle.  This gives a soldering iron the chance to heat up the pad locally without the ground plane "sinking" the heat throughout the entire PCB.
 

Good job Tam. Looking good. Hopefully I'll have everything ready for you to test out.

Thanks for letting me use your design!

Ps. Arent you supposed to put enough solder to wick up to both planes?

http://www.diyforums.org/SSMH/construction/PCB-7.jpg

"When you look at the other side, inspect each pad for a "wicking" solder joint. The solder should travel all the way through to the other side and climb up slightly on the lead. If it doesn't, apply a slight bit of solder on the other side around the lead and the pad - just enough to make it look as if the wicking worked"

When I do double sided boards, I plan ahead knowing there are no plate through holes.

If a component needs to be connected to a ground plane but covers up it's solder point,

I place a trace on the solderable side that is as short and thick as possible that leads

to a point where I can make a "via" to the ground plane. If there is enough clearance

under the component (or you don't mind it sticking up a bit), this point could be under

the component. You could also make the hole for the component a little bigger and just

solder an extra wire through the hole before hand to make a plate through hole.