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Saturday, February 18, 2012

Desk lamp leds retrofit with diy constant current driver

Continuing my previous post about diy constant current boost driver for 9 leds in series, here is a mod for my burned out desk lamp.
I've designed new schematics with 4 mosfets in parallel, because this is only mosfets I had on hands and they are pretty low power with high Rdson. So I decided to use as many as I can.
New schematics:

Then I tear my desk lamp apart, throw internals away except power switch and measured insides how to fit driver pcb.
With this measurments I designed new pcb:

As long as this driver can drive 9-18 leds in series I want to use 3 modules in parallel with 9 leds in series each.
Here is one module pcb assempled:

What diy project without hotglue? Hotglued new driver assempled pcb in place.

New design has push button to switch power modes from low light to max output light. So I drilled a hole to fit this button in. It's pretty invisible and handy to switch light output.

3 led modules glued in place of cfl bulb:

And now it shines my desk, well actually just wall behind my lcd monitor =)

Sorry forgot to picture the whole build.
This project is Open Source and Open Hardware as all what I'm doing here. So take a peek inside the sources and schematics at bitbucket.org and fork if you want.