I recently picked up a bunch of minuscule Chinese USB LED Lamps. You’ve seen these amazing gizmos before, I’m sure, under a variety of names in places ranging from local street merchants to online electronics stores. Even though all of them seemed to work without any problem, there’re a few little things you might want to know if you’ve a similar device or are thinking about getting one alike. So, let’s take a quick look…
USB LED Lamp – Quick Review
The lamp looks amazing for the price (₹50), and seems to be a good pick for emergency lighting applications. The simple and elegant cool-white lamp did a fine job of lighting up a relatively moderate area, and I started getting the outcome I expected from it.
A quick test with my trusty “Charger Doctor” showed the overall current consumption was around 40mA. That’s fantastic!
In my quick view, this is a nice little light small enough to not be protrusive but bright adequate to aid in getting around in the dark. I’ve tried it with different USB power sources and works well so far. Simply, minimal features blend with minimal design here – there’s nothing redundant. Sure, I realize it’s not as lustrous as a luxurious USB lamp, but it’s all I really need for my little tasks!
USB LED Lamp – Quick Teardown
Now it’s time to see what’s inside this cute piece of electronics, right? Well, you can see some photos I took of the inside of the lamp in this session. If you want to take one of these apart to see the inside, it is good to know the translucent white dome is just a press-fit type, that means it’s not glued to the rest of the shell (the build quality is about what you’d foresee from something at this funny price point).
As it seems, there’s nothing else on the PCB apart from the USB-A male plug, a pair of SMD2835 cool-white LEDs, and a 30Ω chip resistor.
Below is the schematic I prepared for you!
As a quick aside, when it comes to power consumption, the pretty little current draw (~40mA to 60mA) is cheerful, but sometimes poses a problem because many USB power banks do not recognize this USB lamp as a suitable load (a little hack will fix it – more later).
While leaping to the next…
Now I am thinking how to design a retrofit automatic emergency light for smartphone power banks using this cheapo USB LED lamp. Actually, the blueprint is ready, what follows is the construction and testing of the prototype. More to come soon!