Exploring a solar Mandala light

These lights are all over the Internet at the moment, often with very fake AI generated adverts showing them as being huge, very bright and sometimes rotating. I've not seen a rotating one yet, although it is possible and would be a nice effect.

The primary science of the effect is based on a single point source of light casting a sharp image through a pattern, that can be punched or laser cut metal, or printed glass or plastic.

The effect needs a small bright source of light. If you try to use a bigger point of light it reduces the sharpness.

This version is based on a classic solar lighting circuit with a dedicated chip that boosts the voltage using an inductor to allow a higher voltage LED to be run from a classic NiMH cell.
There is a little bit of extra circuitry to ensure a continuous DC current to ensure reliable operation of the colour changing LED.

Thee are a few things that will cause this light to fail over time. Some of them can be addressed and some are more difficult to prevent.
The trickiest one to resolve in an outdoor situation is the probability of the metal case rusting away and staining the wall it's mounted on in the process. If you really like the effect it may be viable to 3D print a replacement case that resists rusting and can be swapped when needed.
The issues that can be resolved are mainly waterproofing the solar panel, electronics and LED.
When water seeps in behind a solar panel it can cause progressive electrolytic erosion of the solar panels components. It's good to seal it from both sides. UV resistant clear garden tape can seal the front of the panel and buy extra lifespan, but inside will require the application of a suitable sealer.
The circuitry can be coated in lacquer or grease to keep the water away from it, and it is often a good idea to bypass the switch with a blob of solder too, as they are prone to internal corrosion.
The NiMH cell holder can also be coated in a suitable grease to exclude moisture and oxygen from the battery contacts.

Placement of these lights is complicated by their wall mounting nature. A solar panel will collect the most energy during the day when it's pointed at the path of the sun across the sky. The fact the light is on a wall means the solar panel can harvest less energy due to its angle in relation to the sun. You also have to be careful to mount them where the light will get the maximum direct sunshine exposure without it being blocked by buildings, trees and other foliage.

You can find these lights from many sources, possibly including local shops. I don't recommend buying them from the suspicious online adverts as they are often overpriced.
This one came from AliExpress (not a sponsor). If you want one from there then here's an affiliate link to this one:-
https://s.click.aliexpress.com/e/_c3baNxr5
The cost should be around the £5 mark (plus whatever grab-tax your local fat cats have applied.)
As always, shop around for a good deal, and remember that you may be able to find them in local shops.



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