How can I find Bipolar Junction Transistor (BJT)?


#1

I am looking for BJTs. More specifically this BJT from STMICROELECTRONICS. Thanks for your help in advance.


#2

A search for “power transistor” in frtizing parts search turns up pnp and npn power transistors in a TO220 case. The schematic is a single transistor rather than darlington though so if you want an accurate schematic you would need to create a custom part and modify the schematic svg to darlington. However a quick google search indicates there is a tip120 available in the adafruit fritzing library available on github as well which may have a correct schematic. I’d try their first as it indeed has the darlington schematic although it is pnp. If you need the npn it should be simple to modify that part to be npn (I can do it for you if you need it).

Peter


#3

Hey Peter, Thanks a lot for your reply and my apology for the late respond. different time zones :slight_smile:
off course that would be a great help if you could make it for me. It will be even a bigger help if you could teach me how to do it myself too.


#4

Turns out I was looking at the schematic wrong, it is in fact npn now so the adafruit part should work as is. It is available for download from:

with load instructions at:

As to making your own parts, a couple of tutorials:

If you need the pnp version (looks to be Tip125 and up) what I would do is export a copy of the adafruit tip120 use 7zip to unzip the fzpz then use Inkscape to edit the schematic svg and change the direction of the arrow on both transistors. Then save the new svg (removing the px on font size that Inkscape adds) then edit the fpz file to change the metadata to indicate the new part is PNP rather than NPN and change the part number. Then use 7zip to rezip the part for import to Fritzing. I can do it quite a bit quicker than I can type it :slight_smile: , but if you aren’t familiar with the process and Inkscape it isn’t necessarily as simple for you (although it is a good skill to aquire, it just takes some time to learn). If you in fact need a PNP feel free to try an make it and ask if you have problems. Always happy to help people making new parts.

Peter


#5

Thanks a lot Peter. I will go forward with what you gave me. I have also received some replies in element14 forum. you might like to see that too.