Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Bright light from white light connected 240ac through 1k

Tags:
  1. May 30, 2015 #1
    I have connected 4 White LEDs with 240ac main through 1K resistor in series. The brightness of the output is not satisfactory. What can i resolve this issue?

    Thanks
     
  2. jcsd
  3. May 30, 2015 #2

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    In what way is the brightness "unsatisfactory"?
    How bright do you need?

    Have you tried using more LEDs?
    Have you tried wiring them in parallel?
     
  4. May 30, 2015 #3
    Or lowering the resistance?

    Diodes are often rated for their DC current. Often this is because the junction overheats if over driven. So if the LEDs are pulsed you might be able to go a little over their DC rating since temperatures are based on continuous current draw.

    If that's not enough, use a diode rectifier and a capacitor to make your current DC. I doubt the power needs to be too clean, so nothing fancy.
     
  5. May 30, 2015 #4

    Baluncore

    User Avatar
    Science Advisor

    What is the white LED you are using?
    240VAC with 1k in series will give a forward current of 240mA, then the reverse voltage will destroy the diodes.
    The 1k resistor will need to be rated at 60 watt.
     
  6. May 30, 2015 #5

    jim hardy

    User Avatar
    Science Advisor
    Gold Member
    2016 Award

    Baluncore picked up on the fact something seem very wrong in your description.

    What you describe should have already gone up in smoke.

    Can you assure us somehow that you experiment is not about to hurt you or some tiny fingers in your household ?
     
  7. May 30, 2015 #6
    Since he got some light out of the diodes, I assumed he used appropriate parts.

    Working with 240V is dangerous. Don't do it unless you are a licensed professional.

    If the parts were chosen properly, the circuit should work. If they weren't, out comes the magic smoke. (At 240V this could be dangerous in so many ways.)
     
  8. May 30, 2015 #7

    Drakkith

    User Avatar

    Staff: Mentor

    Agreed. Pmostafa, I'm locking this thread for the time being. If you wish, please send me a message and we can discuss reopening it.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Bright light from white light connected 240ac through 1k
  1. Light from radio waves (Replies: 18)

Loading...