Resistors

Discussion in 'Architecture & Engineering' started by John99, Nov 24, 2008.

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  1. MacGyver1968 Fixin' Shit that Ain't Broke Valued Senior Member

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    Gold is 5%, and silver is 10%...not sure about no band...how would you tell which is the first band, if there wasn't a tolerance band?
     
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  3. Read-Only Valued Senior Member

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    Hi, Mac,

    It's just compressed carbon. Except for the precision ones which are wirewound.
     
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  5. MacGyver1968 Fixin' Shit that Ain't Broke Valued Senior Member

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    You're always full of useful information RO!

    I get wirewound when I drink too much strong coffee.

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  7. leopold Valued Senior Member

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    answer 20%

    the bands are grouped at one end.
     
  8. MacGyver1968 Fixin' Shit that Ain't Broke Valued Senior Member

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    Ok..

    Brown is 1

    Black is 0

    Blue is 6

    First digit is 1...second digit is 0, with 6 zeros behind it.

    so it would be 10,000,000 ohms or 10 Mohm.

    Come to think of it, you always have a tolerance band or you wouldn't know which way to read the bands.
     
  9. MacGyver1968 Fixin' Shit that Ain't Broke Valued Senior Member

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    nm...i was posting while you answered. I done learned me somethin' else

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    Maybe some lurkers learned to read color codes on resistors.

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    Last edited: Nov 27, 2008
  10. leopold Valued Senior Member

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    the "ohm" part can be dispensed with and you use just the M instead.
    10M is 10 megohm.
    10K is 10 kilohm.
     
  11. Read-Only Valued Senior Member

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  12. MacGyver1968 Fixin' Shit that Ain't Broke Valued Senior Member

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    For the purpose of this thread, yes...since we're only talking about resistors. But in proper electronic notations, M only means mega.. you need a unit, to tell what your talking about...and I don't know how to make an "omega" symbol on the keyboard to indicate ohms.

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  13. leopold Valued Senior Member

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    yeah, i see your point.

    another question for you.
    the transconductance of a vacuum tube is the same as beta of a transistor.
    what greek letter represents transconductance?
     
  14. MacGyver1968 Fixin' Shit that Ain't Broke Valued Senior Member

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    Not sure...we didn't discuss vacuum tubes when I was in electronics school back in '94. I only have a two-year degree..so my knowledge is rather basic...and getting rusty.

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    That's kinda one reason I've been trying to participate in these electronic threads..so I can refresh knowledge that I'm starting to lose due to time.

    What's the symbol?, and could you give a brief explanation of transconductance?
     
  15. leopold Valued Senior Member

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    mu.

    transconductance is essentially the current flow through the tube at a given grid voltage.
    edit:
    For vacuum tubes, transconductance is defined as the change in the plate(anode)/cathode current divided by the corresponding change in the grid/cathode voltage, with a constant plate(anode)/cathode voltage. Typical values of gm for a small-signal vacuum tube are 1 to 10 millisiemens.
    - from wikipedia
    end edit

    the naming of vacuum tubes are systematic.
    diode, two elements, plate cathode.
    triode, 3 elements, plate grid cathode.
    tetrode, 4 elements, plate 2 grids cathode.
    pentode, 5 elements, plate 3 grids cathode.
    the naming for the grids starting from the cathode are:
    control
    screen
    suppressor
    note that the heater is not an element unless it is the cathode itself.
     
    Last edited: Nov 28, 2008
  16. John99 Banned Banned

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    There is a power switch with four wires. What i did was change two wires, one white and one black and now the amp works good as new.

    Anyone know what the significance of the colored wires is? What about positive = RED and negative = BLACK? Why is the sometimes a white wire and a red wire? And how come one of those is positive?
     
  17. leopold Valued Senior Member

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    the significance of colored wires is to make it easier to troubleshoot the circuit and to a lesser extent to tell what kind of voltage is on the wire.
    in most circuits red does indicate positive and black indicates ground.
    believe it or not, in AC circuits the white wire is ground while the black is hot (unless this has changed in the last few years)
    except for the AC circuits mentioned above there is no code for wire colors.
     
  18. John99 Banned Banned

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    Thanks. That is what i wanted to know.
     
  19. orcot Valued Senior Member

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  20. MacGyver1968 Fixin' Shit that Ain't Broke Valued Senior Member

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    Bad ass! Way to go! Rock on my brother!

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