OK, guys, thanks for the answers about the electrolytic capacitor.  Glad 
to know I was right. 

Now, if I am not wearing out my welcome, one more question.  A friend 
sold me a box full of old capacitors, resistors and TTL chips.  He said 
that he bought them from some surplus place many years ago, but never 
had any need for them since it turned out to be more trouble than it was 
worth to go through a whole box looking for some particular value -- he 
would rather just go to Radio Shack and buy a new one.  But I figure 
that I can use them in my lessons.  Only problem is, I have heard that a 
capacitor will go bad after a certain period of time, and cannot think 
of a good way to test one, to see if it has gone bad or changed value.  
(A resistor I can check, of course, and a TTL chip I can check).   Any 
good advice for someone on a low budget?

Thanks,
Bill

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