Hello, I bought some large "grab-bags" full of electrical components (I was looking for a good deal). But while trying some of the transistors out, I noticed that they're not all the same. They ALL look like this: http://quality-deal.com/osCommerce/images/MPSA06%20NPN%2080V%20500mA%20General%20Purpose%20Transistor.jpg [Broken] but with different codes on it, of course. In fact, about half don't even have anything on the face. I then built a small circuit that I could test them out with. About 1/3 of them proved to be NPNs. I could find no PNPs though. And no SCRs (not even sure if SCRs can look like that). The rest are a mystery. About half of them release nothing, not with a charged or uncharged base. And the few rest seem to just act like bridges that emit the collection and base charge, again regardless of the bases charge. The questions are: How do I know identify which ones are what? And what useful function do the other 2/3 even provide?? I'm really new to this, so take it easy please. ;) Thanks for any help you be able to provide!