xmas tree LED (3D PCB project) power options?

If you watch the OSHPark thread you saw my 2.5" 3D xmas tree project. I am looking for how to power it, the idea's I've came up with are-

1. A single use CR123, the total draw with a max load of LED's will be around 120mA (however no need to populate all 0805 SMT LED's, you can use only a few if you want) so runtime would be very good but my grandma has no idea what a CR123 when it does die lol.

2. A small solar panel charging something, maybe a R/C coin cell or a 16340 (I'd like to use a 10180 but cant get the SMT cell holders as cheap as the $1 for 5 CR123 holders) or even one of the R/C helo Lipo's

3. A buck converter and make it hang as a tree ornament (my least favorite idea but maybe easiest for the people I plan to gift them to) and make it plug straight into a xmas light strand (remove a bulb and plug in into the socket, I've seen several ornament run like this including my all time favorite NCC-1701 ornament lol)

These will be given to my mom, my grandma and my wife (tho she knows about the project and simply recharging 16340's isnt an issue for us). This is also completely open source so anyone else that can build boards can do this too (boards are NOT ready for order yet).

So I know I have 2/3 of the options as non rechargable but I still thought this forum would be best cause the idea I like best is the small solar cell and coin cell / 16340 / LiPO R/C heli cell (or possible even recycled cell phone cell's). What am I looking at needing to do this? Is there a small (MUST BE CHEAP) panel (maybe around / <6" square) I could use for this and not need some other components? (A single SMT component mounted on the xmas tree would be cool but not some in-line box that needs to be between the panel and the cell. Also I plan to have this thing run all the time so it will need to allow charging while running (or even have the panel provide enough power to run the LED's on their own)

I don’t follow the thread because its length approaches the Affordable Care Act at this point but holy higgs-boson this sounds like a wonderfully cute little project. :slight_smile:

Thanks, this is V0.1, I’m already on V.05 (which has no more big Cu circles and instead has individual 0805 pad’s all over). I also have the CR123 holders on order so I can make a .lbr part for them.

note the slot is not rendered but this is the bottom board (with slot at the top), this is where I plan on most of the needed components mounting including [if I end up using one] the uC). Note the two larger copper pad’s in the middle, that’s where they will make electrical contact with one-another as well as physical attachment.

Bottom board top side

upper board, top side

At 5x5mm these are $40 for two sets of 3 boards (PCB’s ONLY, excluding all components). My original hand drawing was for 5inch tree’s but that was $100 for the PCB’s alone (still looking into other PBC fab’s, can get them done in different colors (including red/green or even white) in china for $75 total for 10 set’s, just gotta figure out the time to get them here and shipping costs.

Would anyone be interested in purchasing completed tree’s? Not as a money making venture / product I offer (ust a few of them to get get mine paid for, I would only ever do the one run of 10 boards) probably sell for around $50 with the full load of mulit-color 0805’s and all components.

Another Idea,

Wireless induction charging, have some sort of commercially available base and have it charge up while its sitting on the charger, then you can eitherleave it there or carry it somewhere else to display (it’d also take CR123’s if this happens)

After doing research all day and consulting with my uncle over the weekend (a very high level EE) it looks like I’ll be using this photocell-


I’ll be attempting to make a logic circuit to control charging (when the LED’s are off) along with a photoresistor to adjust brightness based on ambient light (tho I can tell you now this will be the first function dropped if its to hard).

This is really coming together, I’m excited! My uncle even asked me to make one for his wife, now that’s saying a lot!

Reading the datasheet, it looks like this PC is so smart I might be able to do everything based off using 2 of these (one for charging, one for controlling the other stuff) and a photoresistor, no uC required (tho no twinkle, just variable brightness based on ambient lighting)

geezums, that’s small.

With this level of complexity, and limited run, I think the project has moved beyond my interest, I’m sorry, but I don’t doubt you’ll sell every spare you make, CK :slight_smile:

18650 cell plus one of those TP4056 USB charger boards from Banggood with the protection IC on it…

The Xmas tree or the soic16 PC? Yes that thing is tiny, think I’ll be ordering a bunch of those for other projects (aka random crap I spend months to build only to play with for 5 minutes before its “old” and take it apart to rob components for whatever’s new, damn ADHD when it comes to my personal projects.


or stacked 2032 for 6 vdc

6v wouldnt work cause that PC I’ve picked out is only 4vout so it couldnt charge 2S 3v cells (if those are even rechargable)

These (digikey) appear to be the connector’s used on the R/C heli LiPO soft pack’s I have, can anyone confirm (the standard type all micro-heli’s take)? I’m liking that option if so, just plug the cell straight into the right angle connector on the board nested up in the corner where the 2 boards make an X