thewumpus99
Donating Member
I recently came across www.tbichips.com/drac/ which has a pretty authoritative how-to on DRAC ratio calculation, but much more importantly, on jumper configuration to achieve your desired ratio. Plus it doesn't seem to contain any jumper table errors, which differentiates it from the other sites I've used.
In the past, the calculator at http://www.philter.com/cgi-bin/drac.pl has given me jumper configurations that haven't worked (the last one was 25% off!). Likewise, the jumper table at http://614streets.com/drac.html has some entries that are just dead wrong, e.g., their table would indicate that you should use the same jumper settings for both 0.739258 and and 0.604492! There are at least 8 other lines with this same non-unique mapping problem, and I suspect quite a few additional errors. I tried putting together a digital logic table equivelant, and basically, I think that the 614streets table has a nice linear binary relationship from 0.500000 until 0.707031, and then the train totally leaves the rails.
Anyway, http://www.tbichips.com/drac/ seems to be the only table out there that doesn't start any values between .5 and 1.0 with a 0 in the leftmost position (bad), and doesn't have any duplicate mappings. Just one caveat: they number the jumpers the opposite of the pin numbers on the 25072003E chip, and opposite just about every other website, more specifically tbichips calls the leftmost jumper "1" and the rightmost jumper "7".
In the past, the calculator at http://www.philter.com/cgi-bin/drac.pl has given me jumper configurations that haven't worked (the last one was 25% off!). Likewise, the jumper table at http://614streets.com/drac.html has some entries that are just dead wrong, e.g., their table would indicate that you should use the same jumper settings for both 0.739258 and and 0.604492! There are at least 8 other lines with this same non-unique mapping problem, and I suspect quite a few additional errors. I tried putting together a digital logic table equivelant, and basically, I think that the 614streets table has a nice linear binary relationship from 0.500000 until 0.707031, and then the train totally leaves the rails.
Anyway, http://www.tbichips.com/drac/ seems to be the only table out there that doesn't start any values between .5 and 1.0 with a 0 in the leftmost position (bad), and doesn't have any duplicate mappings. Just one caveat: they number the jumpers the opposite of the pin numbers on the 25072003E chip, and opposite just about every other website, more specifically tbichips calls the leftmost jumper "1" and the rightmost jumper "7".
