Cloud Nightlight Color-Changing LED Conversion

Animation of color changing effect

This is a very cheap nightlight I purchased from China and modified with color-changing LEDs. It's based on a similar build by Big Clive. It's a simple modification, but I did have to work through a few issues while creating it, which I've documented here.

Warning: This project involves modifying a device that runs on mains voltage. If you don't have a solid understanding of electrical safety you should not attempt this or any high voltage project.

Here's the night light as it comes. It's a bit cheaply made, but it looks very nice:

Cloud nightlight stock outside view Cloud nightlight stock inside view

Before tearing it apart, I checked the current going through the stock LEDs, and it was around 8-9mA with the light connected to 120VAC @ 60Hz. That’s well within spec for the color-changing LEDs. The LEDs I used can be purchased from various suppliers in China. They change color automatically w/o any external control.

Before adding the new LEDs, I had a problem to solve - Clive’s nightlight has a through-hole circuit board, but mine is SMT. The LEDs I wanted to use are not. I posted about this on Clive’s Patreon page, and heard back from the man himself. He suggested soldering the LEDs sideways across the SMT pads and folding them upwards. So that's what I did:

Cloud nightlight - new LEDs soldered Cloud nightlight - new LEDs folded

And it worked! But I found my second problem: After I installed the cover, I noticed that my nightlight have three distinctive “hot spots” where the LEDs are:

Cloud nightlight - new LEDs lit Cloud nightlight - new LEDs hot spots

That’s because I didn’t use diffused LEDs like Clive did. Ordering diffused LEDs from China would take several more weeks, so I came up with another solution: A Dremel with a small wire wheel brush. With light pressure and the lowest speed setting on the Dremel, I very careful roughed up the top half of the LEDs. This gave them a diffused output that makes the nightlight look much more like Clive’s.

cloud nightlight - LEDs diffused Cloud nightlight - Finished

Perfect! Those with a keen eye with notice that I also cut the leads going to the photo resistor as I want the light to run any time it’s plugged in.

So all's well, right? Well, no. One last problem cropped up: occasionally, the three LEDs all reset, turning back to red and starting their color changing cycle over. It ruins the pleasant effect of all the colors going out-of-sync and blending, so I wanted to solve it.

I noticed the circuit doesn't have a smoothing capacitor on the bridge rectifier output, which is common on other LED bulbs and night lights I've worked on. I had some 400v, 4.7uF capacitors left over from other projects, so I soldered one to the output of the bridge rectifier. While I was at it, I also removed several components that were no longer needed since the photo resistor isn't being used. Here's the final modified cloud night light:

Night light with capacitor added

I'm happy to say that since making these changes, I haven't seen the LEDs reset and the light works great. Thanks to Big Clive for the idea!

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Posted 12/15/2018.