Upgrading LED Night Lights with spare Power LED's

[EngrPaul]

Everytime I upgrade a flashlight, I take the old emitter (Luxeon, Cree, etc.) and save it for my night lights.

Nightlights fade and lose whiteness after a few months, and even new they are quite blue or purple.

I have a few different brands, and almost always they have three shaved 5mm LED's placed in a triangle shape in the middle of the PCB. These are hooked up in series.

I unsolder the three LED's, and add a resistor and Power LED in it's place.

The best resistor to use is 150 ohms, attached in series to the emitter. This provides about the same lighting level from one power LED as the original 3 LED's did.

The result is better white light that is much less blue than the nightlight comes with. There is no need to heat sink the LED, it only runs at about 1/8 watt.

I have a dozen LED nitelights that I've modded, and they are all brighter than a new stock lite, even after two years constant usage.

I have a few more to do, is anyone interested in pictures of the procedure?

 

[Nitroz]

Now I know what I can do with all these old LEDs, besides change out my car interior lighting.

I would like to see your work on this.

 

[Illum]

Luxeon stars mounted inside copper tube ends looks and works awesome on low currents, around 100ma, I'm pretty sure they can light up at 25ma

If you set your resistors for greater than 350ma prepare to heatsink them to something, because they don't last too long before you smell smoke, I haven't bought any LED night lights but if I were to upgrade them to high powered LEDs I'd consider using some of my older stock luxeons. At 25ma I think the star heatsink should suffice

CREEs can be put under 15ma...but they don't have much heatsink to work with

 

[EngrPaul]

This mod provides about 50 mA with a 150 ohm resistor. Do the math, it could be a little brighter in exchange for possible reduction in emitter life.

Just did another one, taking pictures. Uploading now!

 

[EngrPaul]

This is my mod method. Use at your own risk. Do not attempt unless you understand electronics and proper soldering methods.

Top and bottom (this is two nitelites)

Here's the parts to be installed... a 150 ohm resistor and an old Luxeon emitter

First, removed two (or more) case screws and separate cover.

Next, remove two (or more) PCB screws and push it out of the plastic by pressing on the plug.

Now the board is removed, here is what it looks like on both sides.

Identify by standard 5mm LED cathode/anode and series LED circuit which is (+) and which is (-)... use marker to label connections.

Desolder 5mm LED's.

Install the resistor in the (+) and (-) holes.

Solder the terminals

Snip one resistor tail, partway down the tail like this:

Solder the emitter in the gap, paying attention to the polarity of the particular LED.

Reassemble fully, then test.

 

[Illum]

50ma is actually quite bright using a luxeon, you sure you want to use it as a "nightlight" ? :duh2::naughty:

 

[EngrPaul]

50ma is actually quite bright using a luxeon, you sure you want to use it as a "nightlight" ? :duh2::naughty:

:devil: ??? Not me!

This particular nitelite has two lighting levels, selectable by pressing the transparent sensor button in or out like a bic click.

I am making the assumption the original emitters were driven at 20 mA, and the circuit is capable of providing the same voltage when more current is called for.

This is not shockingly bright... about as bright as the original light, but much warmer in color. :naughty:

 

[jtr1962]

The circuit in those night lights probably uses a capacitor (likely the big square red one) as a reactive element to limit current flow. If so, that means you don't need the resistor. The LED should be driven at the same current without it but you'll be dissipating less heat.

 

[EngrPaul]

The circuit in those night lights probably uses a capacitor (likely the big square red one) as a reactive element to limit current flow. If so, that means you don't need the resistor. The LED should be driven at the same current without it but you'll be dissipating less heat.

Interesting. Next time I open one up (maybe later today), I'll try that. Worst case, I blow up a unloved Luxeon... :tinfoil:

 

[LEDninja]

50ma is actually quite bright using a luxeon, you sure you want to use it as a "nightlight" ? :duh2::naughty:

With my poor eyes I gave up on the little LED nitelites and am using 1W warm white Luxeon bulbs in standard household fixtures. Top kitchen, bottom bedroom (ceiling bounce uplight).

I tried some of the newer 2W Cree bulbs but they are too bright and I got 1 in my bed headboard light as a reading light (old picture, different bulb) and another behind my computer screen shining underneath it on my keyboard (no picture).

I've pretty well given up on 5 mm LED based lights.