On 09/04/2010 12:29 AM, N_Cook wrote:
For old electronic equipment it is a common thing to do is restuff the outer
can of failed dual electrolytic capoacitors , like these in form
http://jensencapacitors.com/public/b...t6elytdual.jpg
(3 terminals because 2 are commoned usually)
about .5mm thick 45mm long 35mm diameter or so.
The original has 2 capacitors built concentric to one another, inside.
Fortunately modern ones , singley, for the same rating are smaller in
volume, but as separate , to get enough space you have to oval out the can a
bit to fit 2 in side by side.
How to oval out the closed end without deforming to flats/overhangs. I do
not know if the original is spun or annealed&pressed. I seem to remember
that to anneal aluminium its a matter of coating with soap and heating till
it goes brown, but what to do next to loose metal and before or after
sqashing to oval. I fix a tight steel band (a standard capacitor clip) about
5mm from the closed end before squashing in a vice to minimise the flats,
but I would like to find a better way. It would be nice to dome the flat top
or create a saddle of 2 small domes to the top would loose metal and look ok
but how to do with minimal equipment.

Getting outside of your box for a second, what about using more than two
caps, in whatever parallel arrangement is needed? Three, four and seven
caps will all pack into a circle much more efficiently than two; that
may give you the volume you need. For that matter, some searching may
find you some short wide caps that can be stacked.

Just a thought...

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" was written for you.
See details at http://www.wescottdesign.com/actfes/actfes.html