Needing a series-parallel combination resistor circuit calculator

Discussion in 'The Projects Forum' started by jasonbengiat, Mar 13, 2007.

  1. jasonbengiat

    Thread Starter New Member

    Mar 13, 2007
    1
    0
    I am making a game, and need 6 resistors for some leds. All of the leds are 20 mA. The circuits are shown below. Can anyone tell me what resistors I need? Can you also direct me to a web page where I can find a resistor calculator that will tell me what resistors I need in the future?
    Thank you,
    Jason

    Circuit 1)
    _____________________________________________________
    | | | | | | |
    | 1.85 volt 1.85 volt 1.85 volt 1.85 volt 1.85 volt 1.85 volt
    | led led led led led led
    | |_________|_______| |________|_______|
    | | |
    9 volt Resistor 1 Resistor 2
    battery |_________________________|
    | |
    second |
    9 volt |
    battery |
    |___________________________ |

    Circuit 2)
    _____________________________________________________
    | | | | | | |
    | 2.0 volt 2.0 volt 2.0 volt 2.0 volt 2.0 volt 2.0 volt
    | led led led led led led
    | |_________|_______| |________|_______|
    | | |
    9 volt Resistor 3 Resistor 4
    battery |_________________________|
    | |
    second |
    9 volt |
    battery |
    |___________________________ |

    Circuit 3)
    _____________________________________________________
    | | | | | | |
    | 2.2 volt 2.2 volt 2.2 volt 2.2 volt 2.2 volt 2.2 volt
    | led led led led led led
    | |_________|_______| |________|_______|
    | | |
    9 volt Resistor 5 Resistor 6
    battery |_________________________|
    | |
    second |
    9 volt |
    battery |
    |___________________________ |
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Let me refer you to this part of the E-book -
    Volume III - Semiconductors » DIODES AND RECTIFIERS » Special-purpose diodes.

    The section on LED's should answer your questions. You also might want to refer to Volume 1 and how to work with series/paralled DC circuits.

    The formula for you calculations is: R = E/I, where R is resistance, E is voltage and I is current.
     
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