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what is a good general purpose NPN transistor

ElectronegativityElectronegativity Posts: 311
edited 2005-09-26 17:39 in General Discussion
Hi all, what is a good general purpose NPN transistor to use for switching 5V current with an SX microcontroller?

Maybe this belongs in the SX forum, but it seemed more like a general electronics question.

Post Edited By Moderator (Chris Savage (Parallax)) : 9/23/2005 7:32:50 PM GMT

Comments

  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-09-23 19:33
    Hello,

    ·· The 2N3904 and the 2N2222 are the more common NPN experimenter/hobbyist transistors.· You just need a resistor between the I/O line and the base of the transistor to use it.· The value depends on what load you're driving, but generally a 220 ohm to 1K works.· In prototyping and using the transistor as a switch, I always use a 1K.· You can calculate for the correct value though if you want to be exact.


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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • ElectronegativityElectronegativity Posts: 311
    edited 2005-09-23 19:36
    Thanks Chris!

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    I wonder if this wire is hot...
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-09-23 19:37
    I updated your subject line too, since it was about resistors.· =)

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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • ElectronegativityElectronegativity Posts: 311
    edited 2005-09-26 15:56
    Hi Chris.

    The subject line was not a mistake.

    Transistor is a contraction of "transfer resistor."

    smilewinkgrin.gif

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    I wonder if this wire is hot...
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-09-26 17:18
    I understand...Hence the smiley...Many people don't realize the naming convention and therefore would also be confused if you asked what a good brand modulator/demodulator was.· =)· Most would get modem though.· Anyway, did the information help?· About the transistors?· I also use those because they're still available at Radio Shack last I knew.

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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • ElectronegativityElectronegativity Posts: 311
    edited 2005-09-26 17:39
    Yes, thanks for the info.

    I am filling out an order from Mouser to stock up on general purpose parts, but their selection of transistors is so huge that I figured it would be better to ask then just order random stuff.

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    I wonder if this wire is hot...
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