Hi all,

I have a Solar LED Light that is not working, and I want to use this to get back into electronics a little. I'm a Control Systems designer, but this level of electrical work still creates a lot of confusion for me. So I am hoping to use this as a learning project.

The board is a standard design, with a single LED, 1.2V AAA Battery, 2V Solar Panel, a 68uH Inductor and what seems to be a potted IC that is hidden from view.

I have replaced the battery, replaced the LED and replaced the inductor but I guess it could still be the IC? I understand that the Inductor is creating a temporary increase in voltage, though I'm not fully sure how that works. But of course essential to get the LED to illuminate.

The solar panel reads 2V when exposed to light, the battery is brand new at 1.29V.

Using a basic DMM, I can see that the LED is staying permanently at 1.29V. I guess the frequency of the switching would be too fast to see? I have a DSO which I could get out to see if there is any frequency being created? Should this be across the LED terminals?

I have tried to draw the circuit and also my results in testing.

 

Hello there. Welcome to AAC!

The board is a standard design, with a single LED, 1.2V AAA Battery, 2V Solar Panel, a 68uH Inductor and what seems to be a potted IC that is hidden from view.

The potted IC, also known as Chip On Board (COB). May be defective.
But if you could take a photo of the board, both sides, maybe we can detect,some other anomaly.

 

Hello there. Welcome to AAC!

The potted IC, also known as Chip On Board (COB). May be defective.
But if you could take a photo of the board, both sides, maybe we can detect,some other anomaly.

Have attached a few pics. Not the finest board I've ever seen.

 

The "blob" IC is a simple high frequency switching inverter. It uses the back emf of the inductor to boost the voltage from the battery so it is high enough to drive the LED.
It is probably dead.

 

The "blob" IC is a simple high frequency switching inverter. It uses the back emf of the inductor to boost the voltage from the battery so it is high enough to drive the LED.
It is probably dead.

So in order to get this working again, its probably best that I buy a mini prototype breadboard or PCB and purchase a new IC?

Will something like an YX8018 LED Driver be suitable as a replacement for the IC if I tie Battery and Solar Positives together?

 

So in order to get this working again, its probably best that I buy a mini prototype breadboard or PCB and purchase a new IC?

Will something like an YX8018 LED Driver be suitable as a replacement for the IC if I tie Battery and Solar Positives together?

Yes, if you get a YX8018 you can repair the circuit in light you have, or you could rebuild it on protoboard. Here is a link for more information:
https://ez.analog.com/adieducation/...blogs/posts/hacking-an-led-solar-garden-light

 

@Delta prime / @KeithWalker

Thanks both for your help.

 

You are welcome. Have fun.

 

Your LED is shown upside down with the wrong polarity.
if you connect the solar + to the battery + then the solar will discharge the battery during the night. The IC has a diode in between.

 

Your LED is shown upside down with the wrong polarity.
if you connect the solar + to the battery + then the solar will discharge the battery during the night. The IC has a diode in between.

@Audioguru again

Thank you, yes - a schematic error on my part. But the LED on the board is wired correctly (Anode to the PCB positive pad).

Thanks also for the heads up regarding the discharging of the battery.