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USB to Serial NPN transistor — Parallax Forums

USB to Serial NPN transistor

EnriqueEnrique Posts: 90
edited 2009-01-26 02:49 in Propeller 1
On the USB to serial converter an NPN transistor is used to drive the RESn line to a low state but nowhere does it say what transistor is it. Does anyone know?
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Thanks,
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Enrique

Comments

  • LeonLeon Posts: 7,620
    edited 2009-01-25 17:31
    Almost any general-purpose NPN should do, like a 2N3904.

    Leon

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  • EnriqueEnrique Posts: 90
    edited 2009-01-25 17:54
    Thanks again
  • b.p.m.b.p.m. Posts: 59
    edited 2009-01-25 19:43
    query: what USB to serial converter?!?

    is there a circuit out that uses discrete components to convert USB to serial and where can
    i find the schematic for it?

    blake

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  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2009-01-25 20:30
    None with discrete components. All of them use an IC converter chip, such as the FT232R.

    -Phil
  • Cluso99Cluso99 Posts: 18,069
    edited 2009-01-26 00:21
    I use an P2N2222 - just be careful to get the correct pinout (the older 2N2222 used a different pinout).

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  • RaymanRayman Posts: 14,598
    edited 2009-01-26 00:34
    Has anybody tried using MProg to invert the polarity of the DTR signal?· It seems like it should work, but I didn't try it because Parallax didn't do it...
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2009-01-26 01:21
    Yes, and apparently it works. Read about it here.

    -Phil
  • AribaAriba Posts: 2,690
    edited 2009-01-26 02:49
    Rayman said...
    Has anybody tried using MProg to invert the polarity of the DTR signal? It seems like it should work, but I didn't try it because Parallax didn't do it...

    I do it also on 2 self made PropPlugs - works well.
    I have a 10nF capacitor between the inverted DTR and the RES pin.

    Maybe Parallax don't do it, because it's cheaper to add a resistor and transistor, than program each unit with MPROG (or they just not had the idea?)

    Andy
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