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Vcc, Vdd, Vss

Discussion in 'General Electronics Chat' started by daviddoria, Apr 16, 2004.

  1. daviddoria

    daviddoria New Member

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    what do Vcc, Vdd, and Vss mean? When is the appropriate time to use each?

    thanks

    david
     
  2. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    I must admit, I've never really known what they stand for - but I've always presumed Vcc is the collector supply for a bipolar device (+ve voltage). Likewise Vdd is the drain supply for a CMOS device (+ve voltage) and Vss the source supply for a CMOS device (ground).

    It works for me :lol:
     
  3. e

    e New Member

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    Vcc = V collector, collector
    Vdd = V drain, drain
    Vss = V source, source

    I think thats it, they represent the single side supply referenced to ground...
    like Vbb = V base, base
     
  4. dave

    Dave New Member

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  5. daviddoria

    daviddoria New Member

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    so what are the 2 different things? like base, base? why isn't it just Vb?
     
  6. andrew2022

    andrew2022 New Member

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    wanted something what looked more complicated?
     
  7. daviddoria

    daviddoria New Member

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    ok...
    then i dont get why "voltage drain" is the +V, and "voltage source" is the ground....
     
  8. mrdudeman

    mrdudeman New Member

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    so a 4017 has Vss and Vdd...i connected ground to Vss and +5v to Vdd, but that seems backward to me after your explanation. it works though...umm :shock: :?
     
  9. mrdudeman

    mrdudeman New Member

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    that is precisely where i have become confused...
     
  10. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    Because on an 'N channel' FET (the most common type) the drain goes to positive, and the source goes to negative - so the drain is the equivilent of the collector, and the source the equivilent of the emitter.
     
  11. daviddoria

    daviddoria New Member

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    ok... little above my head. FET is field effect transistor right? so it works similar to a normal transistor?

    this is where you get the comparison of collector = drain
    emmiter = source

    it seems as though the collector would be the source... (like current waiting to go) and the emmiter would be the drain ( where it goes when the base is turned on)

    right? how does it makes sense reversed?
     
  12. e

    e New Member

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    its the source of electrons, the lower potential... who thought up this naming? hah :lol:
     
  13. daviddoria

    daviddoria New Member

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    ahhh i get it

    so what about Vcc ? is it the same as voltage source? cause the collector on the transistor is the same as the source on a FET, so Vcc = Vss

    correct?
     
  14. mrdudeman

    mrdudeman New Member

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    i think you are correct, but it depends on the type of circuit.
     
  15. simoV8

    simoV8 New Member

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    If the source goes to negative(vss) is that the same as return voltage??
     
  16. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    Sorry!, what do you mean by 'return voltage'?.
     
  17. Sebi

    Sebi New Member

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    Most of power supplyes GND marked as "return".
     
  18. chung lee

    chung lee New Member

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    Vcc, Vdd, etc

    Here's the info about Vcc, etc.:

    BJT FET : these are the two instances where these terms are used.
    Vcc Vdd = Positive
    Vee Vss = Negative/Ground

    You can access this information from:
    The EncycloBEAMia

    There is so much here, it could take months to go through, easily.:eek:

    Chung Lee
     
  19. kuiy11

    kuiy11 New Member

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    what do Vcc, Vdd, and Vss mean? When is the appropriate time to use each?

    Vcc is Voltage Collector Collector
    Vdd is Voltage Drain Drain
    Vss is Voltage Source Source
    Vce is Voltage Collector Emitter
    Vbe is Voltage Base Emitter
    Vec is Voltage Emitter Collecter

    (You better write this correctly when designing or analyzing your circuits)

    (I'm not going to talk about tubes)

    Why the initial duplication (Vcc; the cc)? It accommodates the naming of Voltage "potential" of the Collector, or the emitter, or collector to emitter etc. There is no potential difference at the collector alone so, it is a source voltage, Vcc (the c to c potential at the collector so what ever is there say +5V). Of course it is relative to something, so when measuring this you have to attach your voltmeter (or multimeter) to associated ground ((-) black) of the circuit and the other lead to the Vcc ((+) red). The same applies to the emitter (Vee) and base (Vbb). How the BJT is oriented in the circuit under test is relative to it's own orientation. PNP or NPN. P stands for positive and N stands for negative, so it is a relative junction or node (Some engineer types like to say node) relationship. I'm an engineer, but was a technician in the Navy so either one works for me.

    Someone asked why the Vdd (drain) is positive yet the Vss (source) is negative. This is a matter of convention. Electrons flow not the atom (to much mass), so negative (electron charge = (-)) to positive (+) flow from the source (-) to the drain (+). So some metals have a more negatively charged molecule and others a less negatively charged molecule. Ask any physicist why there would be a huge ground plane. The electrons have to come from somewhere. Electron flow is from negative to positive always, always, always. Did I say always, well it's always.

    Remember your electron valence shells around the atom from your basic electricity classes. Any physics II (or above) or chemistry student would know these facts too and best not disagree. If they do they are refering to charge flow.

    Convention - Two thoughts here. Electron flow and hole or charge flow. That's it. Converse to electron flow is "charge" flow. Charge flow is from the positive voltage source to the negative voltage source. So if you have Vcc (+5 volts) and ground (0 volts) conventional flow states that the charge flow will be occurring in the opposing direction of the electron flow. It starts getting a little crazy after this, so we'll keep it simple right now.

    Imagine an electron going in one direction and the charge in the other (a potential difference causing a reaction).

    This stuff doesn't take months to write about (10 minutes tops). It's extremely simple. Other phenomena and effects can to a few hours to write out, but not this stuff.


    • BJT - Bijunctional Transistor (two diodes split at similar juctions - PNP and NPN).

    • FET - Field Effect Transistor (Has a base that use an electric field to control the conductivity of a charge carrier on semiconductor material: E-H field effects on substraight).
     
  20. kuiy11

    kuiy11 New Member

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    Vcc is Voltage Collector Collector
    Vdd is Voltage Drain Drain
    Vss is Voltage Source Source
    Vce is Voltage Collector Emitter
    Vbe is Voltage Base Emitter
    Vec is Voltage Emitter Collecter

    (You better write this correctly when designing or analyzing your circuits)

    (I'm not going to talk about tubes)

    Why the initial duplication (Vcc; the cc)? It accommodates the naming of Voltage "potential" of the Collector, or the emitter, or collector to emitter etc. There is no potential difference at the collector alone so, it is a source voltage, Vcc (the c to c potential at the collector so what ever is there say +5V). Of course it is relative to something, so when measuring this you have to attach your voltmeter (or multimeter) to associated ground ((-) black) of the circuit and the other lead to the Vcc ((+) red). The same applies to the emitter (Vee) and base (Vbb). How the BJT is oriented in the circuit under test is relative to it's own orientation. PNP or NPN. P stands for positive and N stands for negative, so it is a relative junction or node (Some engineer types like to say node) relationship. I'm an engineer, but was a technician in the Navy so either one works for me.

    Someone asked why the Vdd (drain) is positive yet the Vss (source) is negative. This is a matter of convention. Electrons flow not the atom (to much mass), so negative (electron charge = (-)) to positive (+) flow from the source (-) to the drain (+). So some metals have a more negatively charged molecule and others a less negatively charged molecule. Ask any physicist why there would be a huge ground plane. The electrons have to come from somewhere. Electron flow is from negative to positive always, always, always. Did I say always, well it's always.

    Remember your electron valence shells around the atom from your basic electricity classes. Any physics II (or above) or chemistry student would know these facts too and best not disagree. If they do they are refering to charge flow.

    Convention - Two thoughts here. Electron flow and hole or charge flow. That's it. Converse to electron flow is "charge" flow. Charge flow is from the positive voltage source to the negative voltage source. So if you have Vcc (+5 volts) and ground (0 volts) conventional flow states that the charge flow will be occurring in the opposing direction of the electron flow. It starts getting a little crazy after this, so we'll keep it simple right now.

    Imagine an electron going in one direction and the charge in the other (a potential difference causing a reaction).

    This stuff doesn't take months to write about (10 minutes tops). It's extremely simple. Other phenomena and effects can to a few hours to write out, but not this stuff.

    BJT - Bijunctional Transistor (two diodes split at similar juctions - PNP and NPN).
    FET - Field Effect Transistor (Has a base that use an electric field to control the conductivity of a charge carrier on semiconductor material: E-H field effects on substraight).
     
  21. kuiy11

    kuiy11 New Member

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    Vcc is Voltage Collector Collector
    Vdd is Voltage Drain Drain
    Vss is Voltage Source Source
    Vce is Voltage Collector Emitter
    Vbe is Voltage Base Emitter
    Vec is Voltage Emitter Collecter

    (You better write this correctly when designing or analyzing your circuits)

    (I'm not going to talk about tubes)

    Why the initial duplication (Vcc; the cc)? It accommodates the naming of Voltage "potential" of the Collector, or the emitter, or collector to emitter etc. There is no potential difference at the collector alone so, it is a source voltage, Vcc (the c to c potential at the collector so what ever is there say +5V). Of course it is relative to something, so when measuring this you have to attach your voltmeter (or multimeter) to associated ground ((-) black) of the circuit and the other lead to the Vcc ((+) red). The same applies to the emitter (Vee) and base (Vbb). How the BJT is oriented in the circuit under test is relative to it's own orientation. PNP or NPN. P stands for positive and N stands for negative, so it is a relative junction or node (Some engineer types like to say node) relationship. I'm an engineer, but was a technician in the Navy so either one works for me.

    Someone asked why the Vdd (drain) is positive yet the Vss (source) is negative. This is a matter of convention. Electrons flow not the atom (to much mass), so negative (electron charge = (-)) to positive (+) flow from the source (-) to the drain (+). So some metals have a more negatively charged molecule and others a less negatively charged molecule. Ask any physicist why there would be a huge ground plane. The electrons have to come from somewhere. Electron flow is from negative to positive always, always, always. Did I say always, well it's always.

    Remember your electron valence shells around the atom from your basic electricity classes. Any physics II (or above) or chemistry student would know these facts too and best not disagree. If they do they are refering to charge flow.

    Convention - Two thoughts here. Electron flow and hole or charge flow. That's it. Converse to electron flow is "charge" flow. Charge flow is from the positive voltage source to the negative voltage source. So if you have Vcc (+5 volts) and ground (0 volts) conventional flow states that the charge flow will be occurring in the opposing direction of the electron flow. It starts getting a little crazy after this, so we'll keep it simple right now.

    Imagine an electron going in one direction and the charge in the other (a potential difference causing a reaction).

    This stuff doesn't take months to write about (10 minutes tops). It's extremely simple. Other phenomena and effects can to a few hours to write out, but not this stuff.

    BJT - Bijunctional Transistor (two diodes split at similar juctions - PNP and NPN).
    FET - Field Effect Transistor (Has a base that use an electric field to control the conductivity of a charge carrier on semiconductor material: E-H field effects on substraight).
     

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