Choosing a transistor (NPN)?

Hey Guys,

Recently I was ordering electrical components online and when I reached transistors I couldn't choose any. I was wondering that can I order any transistor or will it ave to be specific one? I need one for projects like wireless induction, laser tripwires etc. I would really appreciate it if you could help.

Thanks in advance
-Prickly Potato

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-max-2 years ago

I like the jelly bean MJE3055 or TIP3055, it is pretty useful. If you need a MOSFET, I like the IRFP250N. These are good hobby transistors because they will take a beating if mounted to a heatsink, unlike the TO92 transistors. (which is good if you are as clumsy as me when it comes to wiring them up...)

For small-signal TO92 NPN transistors, when I need to use them, I generally go for 2N4401's and PN2222's (more commonly and incorrectly called 2N2222, which is an older variant in a obsolete TO-18 metal package.)


If a project you are working on requires a certain type of transistor, like a PNP or P channel, or JFET, or something even more strange, than those 2 choices are not the right one's. Just make sure to use the right type, and if you can, the same part number that is recommended for the project. (I know from the top of my head that the MJE2955 is the complementary PNP equivalent to the MJE3055.)

kmossman2 years ago

BTW for medium power applications, I like the TIP3x and TIP4x series.

kmossman2 years ago

It usually does not have to be a specific one, but one that conforms to the required parameters like NPN or PNP, hfe, Vce, Ic, band-width, noise, power disspaition, Si or Ge, etc.

Usually the first 4 are the most important.

Also they can be optimized for certain uses, such as switching, RF, etc

Using an 'audio' transistor for an RF application will probably give disappointing results.

Most project will require specific transistors. Other then a kit as i suggested in another one of your posts. It may be best to pick a project/schematic and buy the parts to complete said project. Often times you will have to order more components then needed to complete the project so then you will have spare components to play with.