Tran switches

Discussion in 'General Electronics Chat' started by DexterMccoy, Mar 25, 2014.

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  1. DexterMccoy

    Thread Starter New Member

    Feb 19, 2014
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    Transistors as switches

    How does Q2 work? it's collector is grounded and the base has -13 volts

    What kind of transistor switch is this? it's like a comparator

    The resistance on the base is the negative threshold voltage?
     
  2. DexterMccoy

    Thread Starter New Member

    Feb 19, 2014
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    Here is the schematic
     
  3. DexterMccoy

    Thread Starter New Member

    Feb 19, 2014
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    Pull up transistor switch ( Sources current & voltage )
    pull down transistor switch ( sinks current & voltage )

    Here is the schematic drawings
     
  4. wmodavis

    Well-Known Member

    Oct 23, 2010
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    Schematics are much easier to read when right side up.
     
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  5. DexterMccoy

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    Feb 19, 2014
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    What kind of transistor switches is Q3 and Q4?
    Since the emitter has +15
    and the collector has -15

    What kind of transistor switch is this?
     
  6. wmodavis

    Well-Known Member

    Oct 23, 2010
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    They are PNP transistors.
     
  7. DexterMccoy

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    Feb 19, 2014
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    No I mean what kind of ""SWITCH"" IS IT , since it has -15 on the collector and +15 on the emitter
     
  8. wmodavis

    Well-Known Member

    Oct 23, 2010
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    Sir. I cannot read your mind. If you want an answer to the question you want answered. Your question was "What kind of transistor switches is Q3 and Q4?" I answered that question. They are PNPs.

    Your new question - what kind of ""SWITCH"" IS IT. It is a PNP transistor switch biased properly as such.
     
  9. DexterMccoy

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    Feb 19, 2014
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    Biased for what?

    How is it different then a PNP transistor switch that is Unbiased?

    What does a PNP transistor switch that is Biased do different VS a transistor switch that isn't Biased?

    i don't understand the difference or advantage of a transistor switch that is Biased VS unbiased
     
  10. DexterMccoy

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    Feb 19, 2014
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    These transistor switches have a Bias or threshold voltage on the Bias

    It seems that the transistors switches will only turn ON when it exceeds the Bias voltage

    Take a look at the +Vcc and - Vcc on the Bases of the Transistor switches

    Q1 is a SHUNT switch
    Q2 is what kind of switch? it doesn't shunt or short out the signal to ground, so what is it called?
     
  11. DexterMccoy

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    Feb 19, 2014
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    How does this transistor Q6 transistor switch work?

    here is the schematic
     
  12. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    Hahahahaha!
    Circularity!
     
  13. DexterMccoy

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    Feb 19, 2014
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    I mean it's not a shunt switch, so how do the transistor switch function or work?
     
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