Pimp My Board Contest Results

I did get a couple of responses to my invitation. Well, two, actually.

So congratulations! Free boards will be heading your way in about a month, and I'll throw in most if not all the parts, too.

First was simonov's entry. He's clearly done this several times before. His confident layout ticks all the right buttons: ground plane (check), thermal isolation (check), clean, geometric layout (check). One jumper required, but that's a very minor offence.



While I allowed modifications of the circuit, simonov went and redesigned pretty much the whole thing. CCS replaces the source resistor, current limiter and capacitance multiplier blocks added. The BOM was starting to spiral, and no longer uses my standard parts set so I'd have difficulty supplying kits based on his design. His modifications, although certainly improvements, ended up counting against him.

Next is avroarrow's entry, a double-sided board:



A lot of effort clearly went into keeping the traces short, and the grounds are all together (star ground). Unfortunately the double-sided layout ends up a bit convoluted as a result, and the board space is not used very efficiently. Also he has not yet mastered some of the advanced commands in eagle, like POLY, to get solid filled areas of trace. Good work! You've earned your free boards!

When I first posted the contest it was because I was legitimately a little stuck on the layout, it didn't want to come together for me. I've had over a month to think about it, chipping away bit by bit. My boards ended up something like this:

• 5x8 cm standard quarter Eurocard size, it's double-sided but the top side ground plane is redundant, the boards could be constructed single-sided it still work fine.
• I used a horizontal mount heatsink, Aavid 507302B00000G or 504222B00000G. Or make your own from a bent strip of scrap metal.
• The ground order is rigorously correct, input to output. IN, OUT and V+ pads support standard screw terminal strips.
• The three transistors are close together, with minimal trace length connecting them.
• The hot parts, Q3 and R7, sit on the centerline, away from the edges and hopefully your fingers.

I hope no one is too upset to learn I decided to use my own board design in the end. As consolation, everyone who entered gets the amp in kit form, or close to it!

J-Mo mk. ii project page. You can download my schematic and board files from there.