On 11/24/21 7:38 AM, Chuck Harris wrote:
Depending on the manufacturer, the lead arrangement had another
more practical purpose, it made capacitor orientation irrelevant.
The outer leads were welded to the aluminum can, and were by
convention the negative leads. The inner lead was positive.
It is virtually always the case with radial leaded aluminum
electrolytic capacitors that the outer most lead(s) will be the
negative lead, and the most central lead(s) the positive.
There were some tantalum caps in a similar package that were all
doubles, as I recall.
Yes there are. IBM used two types on boards from mainframe/midrange systems, three- and four-lead capacitors. They're usually +-+ or +--+, to solve the orientation problem. These boards were typically not hand-assembled, but making their orientation irrelevant allowed them to use loose parts in vibratory hopper feeders on the assembly line, rather than the more expensive and larger tape-and-reel component feeders.
These capacitors come in both the yellow dipped tantalum bead styles, usually no more than 1/2" tall, as well as small black molded rectangular blocks, about 3/8" tall and anywhere from 3/16" to 3/8" wide, and 1/8" thick or less.
-Dave
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Dave McGuire, AK4HZ
New Kensington, PA
Dave McGuire