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Troubleshooting A Flickering LED Downlight

I’m using LED downlights in my home as the main light source. One of them became flickering. After some research on the Internet, most of them will tell you that maybe the LED driver quality is not good and give unstable voltage to the LEDs.

So, I changed the LED driver that I ordered from the China websites. It works but a month later, the same LED downlight flickered again. I changed the LED driver again and it came back working again.

Last week it became flickering again. So I decided to change the LED driver again today. This time it does not work. The LED downlight is still flickering. I measured the voltage and current of the LED driver output and they are good and stable.

So I suspect one of the LED light inside the downlight is not working properly. There are 12 LED connected in series. Since the LED is providing constant current so it is ok to short one of the LED. So I short the LED one by one to test if the downlight will stop flickering without the shorted LED in the circuit.

I was right! One of the LED was causing the problem. It was not the LED driver problem! Since I don’t have a spare LED at home, I temporary short the LED legs to prevent it from working. And my LED downlight now working perfectly good!

LED Downlight
LED Downlight

The LED downlight cost was about RM60. The LED is rated at 12W and it has 12 LEDs inside. So each of the LED is rated at 1W. I’m going to replace it with the 1W LED I bought from the China Website for my LED night light project, which only cost me about USD0.04 each. It wastes money if I replace the whole LED downlight with a new one :)

One Watt LED Night Light

This is a very simple electronic project. I built this as a night light in my sleeping room.

The reason for building this was, the existing LED night light that I bought from the Mr DIY is a bit dangerous because it needs to be connected to AC power source and my daughter always wants to play with it.

With this LED night light, I can connect it to any mobile phone’s power bank that has a USB port. And it is safe to play with. It doesn’t get hot even it ran for hours!

One Watt LED Night Light

Bill of materials:

  • A one watt LED (RM0.20)- bought it from the China website.
  • A heat sink for LED (RM0.20)- bought it from the China website.
  • A 39 ohm 1 watt resistor (RM0.10) – bought it from an electronic shop at Jalan Pasar, Pudu
  • A LM317 voltage regulator (RM1.50) – bought it from an electronic shop at Jalan Pasar, Pudu
  • A heat sink for LM317 (RM1.00) – bought it from an electronic shop at Jalan Pasar, Pudu
  • A Mamee instant noodle cup – recycle
  • A broken iPad USB cable – recycle
  • Some card board – recycle

Total cost is less than RM4!

1. First, you will need to solder all the component together. You can refer to the circuit suggested in this website: http://www.instructables.com/id/Super-simple-high-power-LED-driver/

One Watt LED Night Light

2. Make a few card boards that cut into the instant noodle cup shape. Make a hole at the middle of one of the card board and put the LED into the middle.

One Watt LED Night Light

3. Pull other electronic components to the back. Put a layer of white paper at the side of LED for better effect. Pull back the electronic components and screw the heat sink and the LM317 together with the card board.

One Watt LED Night Light

4. Use glue (any) to stick the card board to the instant noodle cup and it’s all done.

One Watt LED Night Light

5. I run some test with the watt meter. It’s working at 0.9 to 1w which is within my expectation!

One Watt LED Night Light

I can bring this light to any where because it is portable and safe. Including toilet! if I don’t want to have a very bright light at the mid night when visiting toilet.

So. What’s next? Maybe a solar panel with rechargeable battery to power this little thing? Stay tuned!

Thanks for reading!

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