Retrovert
Addicted Member
I set forth specific data from the manufacturer and from learned tomes, precisely so facts would be presented. If you dispute the data and explanations from others you should explain why.
In this discussion I quoted from Cornell-Dubilier and from Doug Self. What more do you want? Quotes from Kemet, Nichicon, etc.? How much of the same data would convince you?
Here is a partial summary of the drawbacks of electrolytic capacitors:
(1) In an electrolytic capacitor capacitance falls with frequency, starting at approximately 1k Hz. I do not know how anyone could dispute this. The reference frequency for capacitance is 120 Hz @ 20° C
(2) Capacitance in an electrolytic capacitor is increased by etching plates which requires that plate be covered with an electrolyte. The ions in the electrolyte match the charge, one for one. This movement is quite slow, hence the problems with rapidly changing signals.
(3) Electrolytics have very high Dissipation Factor. This causes ohmic heating, which further changes the properties as capacitance varies with temperature.
(4) Because two electrolytic capacitors are used to form a non-polar, both in series and reversed respective to each other, the signal, of necessity, must always pass through one dielectric. Metal oxide layers perform a rectification effect just like a semiconductor junction. Rectification effects fro aluminum oxides have been known for over a 125 years.
(5) Because the capacitors are, of necessity, series-wired, the overall capacitance is halved. This requires using capacitors of twice the target value, thus requiring larger plates, leading to mismatches between the two sides (non-linear distortion) and great opportunity for defects.
(6) The properties of electrolytic capacitors change over time as the capacitor ages. The manufacturers provide such data. Modern electrolytics have longer wear out periods, having increased from roughly 1,000 hours circa 1970 to roughly 8,000 hours today.
(7) Electrolytic capacitor quality has similarly greatly increased in the prior few decades, including substantial reduction in ESR in the past twenty years. The older units have very poor properties, not that the new units are so wonderful, either.
Where have I stated something that is incorrect or untrue?(2) Capacitance in an electrolytic capacitor is increased by etching plates which requires that plate be covered with an electrolyte. The ions in the electrolyte match the charge, one for one. This movement is quite slow, hence the problems with rapidly changing signals.
(3) Electrolytics have very high Dissipation Factor. This causes ohmic heating, which further changes the properties as capacitance varies with temperature.
(4) Because two electrolytic capacitors are used to form a non-polar, both in series and reversed respective to each other, the signal, of necessity, must always pass through one dielectric. Metal oxide layers perform a rectification effect just like a semiconductor junction. Rectification effects fro aluminum oxides have been known for over a 125 years.
(5) Because the capacitors are, of necessity, series-wired, the overall capacitance is halved. This requires using capacitors of twice the target value, thus requiring larger plates, leading to mismatches between the two sides (non-linear distortion) and great opportunity for defects.
(6) The properties of electrolytic capacitors change over time as the capacitor ages. The manufacturers provide such data. Modern electrolytics have longer wear out periods, having increased from roughly 1,000 hours circa 1970 to roughly 8,000 hours today.
(7) Electrolytic capacitor quality has similarly greatly increased in the prior few decades, including substantial reduction in ESR in the past twenty years. The older units have very poor properties, not that the new units are so wonderful, either.
It is very easy to just say "oh, you're wrong" without supporting data. I set forth the assumptions, the data and charts, the explanations from manufacturers and learned tomes, so that it may be analyzed and responded to.
If electrolytics were so great they'd be used as coupling capacitors, cathode bypass, etc.
