[R-390] Slighty OT: Question about tantalum caps

[James A. (Andy) Moorer]

It used to be that the tantalums had better high-frequency response, and the 
alluminum electrolytics had some nasty breakdown (i.e., blowout) problems 
combined with relatively short lifetime. The electrolyte would dry out with 
time.. Back "in the days" while chasing a low and buzzy B+ rail, I 
experienced a catastrophic capacitor failure that blew the can all the way 
across the room, luckily missing my left ear by a comfortable margin and 
spreading some nasty, corrosive goo all over the power supply. Today's 
alluminum electrolytics are light-years better than those from the 50's and 
60's and can go anywhere that an electrolytic is needed. All the great 
"computer-grade" electrolytics these days are alluminum. To make sure you 
catch the higher frequencies, as noted earlier, parallel it with a .01 or .1 
ceramic or dipped mica or something. As always, keep the leads short and 
avoid too many bends and kinks in the wiring. If you are feeling 
particularly studious, look for the capacitors with the lowest ESR and 
highest lifetime - the Mouser catalog gives you these numbers - but that is 
mostly overkill. Just don't try to lowball it too much.

James A. (Andy) Moorer
www.jamminpower.com