what value of Resistor require.?

Discussion in 'General Electronics Chat' started by sangpo, Aug 29, 2013.

  1. sangpo

    Thread Starter Member

    Aug 17, 2013
    74
    1
    Hi all. I am learning electronic basics.Q1.Suppose, I have a motor a motor which specifications is. 333mA,6 VDC. And I have only 12 Vdc( car batery)
    So what value of resistor should I connect in series?
    Q2.Aagian Suppose, I need 50Ω or 18Ω resistor. but I have 100Ωor36Ω. So how what do I do here.?

    Thank you
     
  2. Shagas

    Active Member

    May 13, 2013
    802
    74
    Well if you just want to connect the motor to see it spin or something then you can use a very sloppy method where you just connect any resistor say....300ohm or something in series and the motor simply won't go over it's maximum revolutions because the resistor will drop the voltage whenever the motor pulls current.
    You can use another slightly less sloppy , but crappy method where you use a voltage divider (google it) of say ... 300 and 300 ohm and connect the motor on the output .

    A better method you could use is using an LM317 voltage regulator . With an adjustable potentiometer you can controll the voltage from 1.2 volts to whatever voltage you battery gives minus two volts . I suggest trying it , it's probably the easiest and simplest method for connecting a motor and varying its speed . You can google LM317 circuits , you will find tonnes of them .

    If you need 50 ohm and you have 100 ohm then connect two 100 ohm in parallel and you have 50 ohm .
    Read some basics on resistors.
    http://www.allaboutcircuits.com/vol_1/chpt_2/5.html
     
  3. cornishlad

    Member

    Jul 31, 2013
    196
    25
  4. JoeJester

    AAC Fanatic!

    Apr 26, 2005
    3,373
    1,159
    those two questions sound like homework.
     
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