transistor equivalents

just generally i was wonder if there is a quicker way for finding equivalents of transistor rather than going through loads of datasheets to find a match or equivalent
thanks for your help

Hmm, a lot of people here know of equivalents off hand, perhaps a database of them would be a useful thing to make :?: . Other than that, searching datasheets seems to be the only way.

You can use only a few "standard" transistors.
1) A 2N3904 or BC547 NPN for most low power audio (up to VHF) frequencies and the 2N3906 or BC557 PNP types for up to 100mA.
2) A 2N4401 or 2N4403 for up to 500mA. There is a BCxxx version as well.
3) A medium power transistor like the TIP31 or BDxxx NPN and TIP32 or BDxxx PNP for medium power.
4) A 2N3055 as an NPN power transistor or MJ2955 PNP.

Sometimes circuits use high gain transistors where a BC547C or BC557C is needed, or higher voltage ratings where the TIP31C or TIP32C is rated for 100V.

Learn the spec's for your standard transistors then use others if their ratings aren't high enough.

RF transistors each have a certain capacitance so pick a replacement from datasheets or a substitution list. :lol:

TR

There are books for that......... 'The transistor equivalant hand book'

hey can i get the link for that book?