Jump to content
Electronics-Lab.com Community

white led


Recommended Posts


  • Replies 171
  • Created
  • Last Reply

Top Posters In This Topic

I used Hewlett-Packard's LEDs for many years. Then their opto business was sold to Agilent who sold it to Avago. Digikey sell these excellent Avago LEDs at a pretty good price.

There are forums for guys who eat and breath LEDs. They talk about the good and new brands of LEDs better than me.

Link to comment
Share on other sites

While testing the board (old project with 52 led's) i applied just about +50 volts and found all the LED's start to work with a very dim light but around 4 of them were very very dim than the other 48 ones which were uniform in brightness. Is this because of the forward voltage rating or will those 4 of them fail fast ?

Link to comment
Share on other sites

  • 1 year later...

Hi AG
:D :D :D ;D I dont live in a tree. I have a 13.5 volt 1.5A battery charger so that charges the battery and also lights up the leds. So when the power goes off it lights for some time taking back up from the battery. My previous image had some wrong calculations. In the image shown here i plan to have 4 such modules(led board 4nos and current regulator 4 numbers). So which would be the best power transistor to use ? the current of one module is 240mA.

post-22691-14279143881374_thumb.gif

Link to comment
Share on other sites

If the LEDs are actually all 3.0V and divide the current equally then each 33 ohm resistor will have a voltage drop of 0.99V. Then if the battery is max at 13.55V the power transistor has a voltage drop of 13.55V - 9V - 0.99V= 3.56V. It will dissipate 3.56V x 0.96A= 3.4W. Any power transistor will work fine with a small heatsink.

Why does your power go off? Can't they fix it so it is on all the time like mine?

Link to comment
Share on other sites


Due to summer season there is power cuts here . They call it load shedding. So need to prepare for it.

It must be difficult to live in a tree. :o

My home is on the ground and my electrical utility company keeps the electricity running for 99.999999% of the time. They also keep the voltage and frequency accurate.
Of course it is not as hot here in summer as it is in your country but we still use air conditioning in summer.

Our electricity use was maximum just before Christmas because of millions of old high current incandescent Christmas tree lights. So the electrical utility traded new low current LED Christmas tree lights for the old ones and now the electicity use is less.
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...

×
  • Create New...