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I need to find a replacement transistor. The only number I have to go by is a manufacturer (of the unit, not the transistor) part number from 1974 which of course leads nowhere. I know it's a silicon NPN TO-220 case used as a relay driver. I know the voltages, I can estimate the current, so I can search for all those parameters but get hundreds of candidates. Is there a way to further narrow down the field to just those with an EBC pinout without having to click through to every single data sheet?

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    \$\begingroup\$ Do you really need any special properties? Sounds like the properties aside from current and voltage capacity and something like "needs at least mediocre current amplification" are all the specs you need – the original designer probably didn't "wisely" choose that transistor either, but used whatever was available. Try sorting by price, restricting by current capability, case and pinout, and use the cheapest one that fits. \$\endgroup\$ – Marcus Müller Feb 5 at 18:42
  • \$\begingroup\$ Once you've selected the parameters which matter to you, sort by price then pick the 1st one which fits your pin-out requirements. Done. \$\endgroup\$ – brhans Feb 5 at 18:58
  • \$\begingroup\$ "restricting by current capability, case and pinout" ... "1st one which fits your pin-out requirements." And how do I determine that without having to click through every single data sheet? \$\endgroup\$ – Duston Feb 5 at 19:35
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    \$\begingroup\$ 2N5298 is indeed a TO-220 NPN, but is BCE. \$\endgroup\$ – Duston Feb 5 at 19:39
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    \$\begingroup\$ @Duston it's not like you'll have to click through thousands of datasheets. More, like, 5, until you find a transistor that works. If you can't do it by the tenth datasheet, well, botch together something that crosses pins. \$\endgroup\$ – Marcus Müller Feb 5 at 21:02
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The best way is to fine tune your search parameters so that the candidate list is reduced. With reduced tight list you really only need to look at data sheets till you find a suitable part....no need to look at every part data sheet.

When considering that it is used as a relay driver do be careful to look at the driving circuit as well. There is a possibility that the component that you are looking to replace is a Darlington with a high current gain.

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    \$\begingroup\$ Mouser has a handy feature where you specify the parameters in multiple columns, which narrows down the suitable products for you. \$\endgroup\$ – Mike Waters Feb 5 at 22:57

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