How Can I eliminate heat loss while stepping down DC voltage.

Discussion in 'General Electronics Chat' started by ritesha1975, Jun 17, 2010.

  1. ritesha1975

    Thread Starter New Member

    Jun 5, 2010
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    0
    I am lighting a 1W-3.2V Power LED with a 12.8V Standard car battery.

    To limit the voltage I put 100Ω-5W resistance (as the resistance with less wattage burns) which step downs the output to 1.7V , this resistance gets pretty hot.

    My questions are:
    1. Is the circuit actually using 1.7 volts or the power is getting wasted as heat from the resistance?
    2. Can the voltage be stepped down to 3.2 volts without heating the resistance?
    3. The 100Ω-5W resistance is very big in size, do we have a similar device in smaller size?
     
  2. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,754
    760
    No matter what u do power will be wasted in ur case.
    U are using a 3.2V Led with a 12V....where do you think the rest of the 8.8V will drop.
    If a resistor is used, heat will be produced and power will be wasted.

    To minimize that u should build a DC to DC converter with appropriate power in mind
     
    ritesha1975 likes this.
  3. Bychon

    Member

    Mar 12, 2010
    469
    41
    Where's wookie when you need him? This is a pulse width modulation problem if I ever saw one. A PWM circuit is much like the DC to DC converter that Rifaa sugested, except it's adjustable. You can buy one or make one, and it will be useful in this circuit and a lot of others.

    or you can build a switching regulator.
     
    ritesha1975 likes this.
  4. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,754
    760
    Hee haa hhaa :D.
    I guess I got to the thread before Sarge did. Besides, if the OP wants PWM, Sgt will show up, he always does.
     
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