You do know that you can also mount caps in PARALLEL.
Two 140vdc 10000uf caps mounted in parallel amounts to 20,000uf or 8 totaling 80,000uF and will probably be cheaper and easier to get than 1 big 80K uF moster.
Instead of mounting 1 big one, you can mound several small ones remotely at the various driver cards. If the 3 cards will each provide say 15 amps, use the rule of thumb uF value remotely mounted at that card as opposed to a monster suitable for 45 amps to commonly draw from.
YOu can aslo limit inrush by using small gage wire as in 16 or 18 gage instead of 10 or 12 from transformer to the 3 caps. Keep in mind that the transformer windings also need ot be considered when you do the inrush limiting deal.
Yes rules of thumbs are good, but you also have to consider what each amp will draw and whether they will draw max current simutaneously. This is where the engineering part comes into play.
Part numbers and prices: no matter how you ask, Digikey and/or Mouser are your best bets.
Alternate sources would be surplus electronics component houses but this will not necessarily be easy either. Electronic Surplus in Cleveland OH has a website and caters to DIY sales - surely there are others. Simply google "surplus electronics components" and take your pick...  |