the difference between the lo-tim and the leach super amps is in the vas stage, it is cascoded, and feedback is taken from the junctions of emittter collectors of output trannies via 270 ohm resistors feeding the bases of the vas drivers.
OK, As Pinkmouse suggested, Advanced Circuits seems to be the low price leader. Boards will be $10.50 each plus reshipping costs. I've built a little padding in for shipping to me, excess will be donated to this website.
The catch is with the trace minimum spacing at 12mils we cannot get more than 2 oz. copper. Heavier would be nice, but I cannot ask Jens to rework his design. How do the rest of you feel about 2 oz. copper?
The catch is with the trace minimum spacing at 12mils we cannot get more than 2 oz. copper. Heavier would be nice, but I cannot ask Jens to rework his design. How do the rest of you feel about 2 oz. copper?
I know Jens prefers the heavier copper, as do I.
Jens: do you think we are running any risk of approaching the current capacity of any of the traces? If not, I am cool with 2oz, which is still better than average.
EDIT: Do we think the cost savings are the new place, or the limit on copper weight?
Jens: do you think we are running any risk of approaching the current capacity of any of the traces? If not, I am cool with 2oz, which is still better than average.
EDIT: Do we think the cost savings are the new place, or the limit on copper weight?
On the Cadsoft website there is a ULP for calculating current capacity of board traces. I haven't used it, but it should be good for a check.
pcbpro will only do 1.5 oz copper at this trace spacing, for about a dollar more. if Jens could bring the spacing up >13 mils, they would do 2.5 oz.
I don't know what the cost impact would be - advanced has a semi-automated system - upload the gerbers and they do a design check. (passed with no errors or warnings) There must be some sort of spacing check built in when you upload them, because they only gave me 1 oz or 2 oz choices. They say they'll do up to 5 oz. copper. If Jens increases the spacing, I'll quote it at 3 oz.
Advanced does offer a student discount, but does not say how much and the boards must be shipped to a university address to get it.
pbbpro did not change pricing from 2.5 oz to 1.5 oz.
Professor Leach's boards do not have nearly the trace width that Jens' design does, and they don't feel like particularly heavy copper. I suspect that we'll be fine with 2 oz, although more would be "better."
Advanced does offer a student discount, but does not say how much and the boards must be shipped to a university address to get it.
pbbpro did not change pricing from 2.5 oz to 1.5 oz.
Professor Leach's boards do not have nearly the trace width that Jens' design does, and they don't feel like particularly heavy copper. I suspect that we'll be fine with 2 oz, although more would be "better."
Bob,
The university shipping address can be arrange. But let us find out what the saving would be and worth the trouble.
I opt for more copper also.
Hi,
I would stay with thin copper.
Then link all the Re resistor tails together with a 0.8mm or 1mm copper wire to the output inductor. This would just about double the copper area running to output.
I would consider the same for the track - fuse to collectors as well.
Not nearly as neat as thick copper but then you can have small spacing, cheaper PCBs and put the copper where it's needed.
I would stay with thin copper.
Then link all the Re resistor tails together with a 0.8mm or 1mm copper wire to the output inductor. This would just about double the copper area running to output.
I would consider the same for the track - fuse to collectors as well.
Not nearly as neat as thick copper but then you can have small spacing, cheaper PCBs and put the copper where it's needed.
I can imagine adding a number of pads on the output trace a copper strip can be soldered to on the bottom side of the board.
But opting for less than 2 Oz boards is not my cup of tea, personally i even have problems going for less than 2.5 Oz. , for one i started to drool when Bob mentioned 5 Oz.
If Andrew is not kidding, please let him be the only one.
But opting for less than 2 Oz boards is not my cup of tea, personally i even have problems going for less than 2.5 Oz. , for one i started to drool when Bob mentioned 5 Oz.
If Andrew is not kidding, please let him be the only one.
Hi,
yes a tongue in cheek suggestion. But what other alternatives are there to avoid Jens having to redesign the PCB?
Is he not trying to pack up for a house move?
yes a tongue in cheek suggestion. But what other alternatives are there to avoid Jens having to redesign the PCB?
Is he not trying to pack up for a house move?
I am happy with Jens's 3oz boards, even if there are only 50+ of us, at 125 dkr.
Too much work goes into this. Why should I begin such a project knowing that the board is of inferior quality? The saving will only buy a beer per board and only if the Customs let it pass.
Too much work goes into this. Why should I begin such a project knowing that the board is of inferior quality? The saving will only buy a beer per board and only if the Customs let it pass.
I agree. Let's go with the original plan of Jens having the boards made and a single point US CA distribution? A lot of fus over a couple of dollars.
Just curious.
If couple of places can not make the boards with the heavier trace unless it is wider in the US.
Is the place in EU making the trace THICKER (Deeper) with the same width for more copper?
Jens obviously design the trace with 3oz copper in mind.
Does someone has an explanation for this. 😕
I want more copper too!
If couple of places can not make the boards with the heavier trace unless it is wider in the US.
Is the place in EU making the trace THICKER (Deeper) with the same width for more copper?
Jens obviously design the trace with 3oz copper in mind.
Does someone has an explanation for this. 😕
I want more copper too!
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