Electronics > Projects, Designs, and Technical Stuff
Cornell Dubilier - WBR capacitors why so expensive
Jester:
I'm replacing most of the old electrolytic caps in an old piece of test gear and they have used a few 100uF, 50V that are quite large (1.5" x 0.5") for their value and quite expensive. BOM calls for BR100-50, the actual cap installed is a WBR100-50. This is an 85 deg C cap, 2000hr, ESR3.9 \$\Omega\$, the tolerance is -10 to +150%, but nothing exotic except the price $10.
In comparison Nichicon TVX1H101MAD are <$2, 1/4 of the size, similar specifications except+/-20%
Or if the +150% is important an Illinois Capacitor 157TTA050M (150uF) $1.46
Why are these so physically large and expensive?
xani:
Quite plainly tech got better. Just make sure ESR difference doesn't matter for the place they were used and you should be golden
james_s:
Do check the ripple current rating as well. A physically large capacitor will often have a higher ripple current rating, it has more mass and surface area to dissipate the power.
Jester:
Re ripple current, I can't find the original data sheet, however the WBR 100-50 , shows 140mA@120Hz and the newer capacitors specify 220mA and 285mA, so I don't see ripple current as an issue.
I have attached the schematic of the circuit, see C32, with the 3k resistors connected the ESR seems irrelevant. The other two are just bulk capacitance at input of voltage regulators.
JD, good eye I should have noticed, I corrected the schematic
Jay_Diddy_B:
Hi Jester,
the polarity of the capacitor C32 is shown incorrectly. It should be negative end to the junction of R99 and R100.
It is a bootstrap circuit that increase the current in R99 when the output swings towards the negative rail.
Jay_Diddy_B
Navigation
[0] Message Index
[#] Next page
Go to full version