Electronics > Beginners
Time to get my feet wet Making an RGB led Heart necklace (with heart shaped pcb)
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Astaldoath:
Im looking for some advice at that im completely new to making a pcb, layout, picking parts (i understand a bit about the parts from watching dave and many other channels in youtube)

I want bright leds. All i will have to work with will be a hakko 888fxd station 65 watt. (or should i go for a ripoff of the 921, i think thats the model) that uses the heater element in the tip? or will the 888fxd do me fine?

Also im not sure what kind of leds to go with. I do want RGB, i dont know weather to go with SMD or Through hole. I know SMD is harder and my hands arent very steady.

Basically I want to make a PCB shaped like a heart, and have like several sizes of hearts within the one heart (does that make sense?) like a larger amount on the outside, then another row with less, another row with less, and so on until I have the heart shaped PCB completely filled with leds in a heart pattern in it.

I was kind of thinking making them seperate almost like how some pcb have notches cut out, like have the outer set of leds be on a part of the pcb, but then have a smaller heart still connected to the pcb with less leds. and so on and so forth instead of 1 big heart shaped pcb, have it be in sections kinda. I will try to MS paint a quick idea tomorrow as its 12pm eastern atm.

If i would use the seperated idea I was planning on having each section glow 1 color at a time, Example - Outer section all Purple/pinkish, next all blue, next all green, next all yellow, orange, and red finally but allow the user to change them with either a remote or some kind of breakout board attached to the heart pcb that they could mount inside a jacket or something. Ultimately this PCB would become a necklace like the RGB bowtie dave got on one of his Mail bags.

Main points:
SMD or Through hole
Maximum Brightness
Diffuse or not diffuse

and maybe a brand of LEDs that are known to be very bright. I started trying to learn Diptrace today and will continue with that. I was looking on adafruit because they seem to have a lot of addressable and multiplex-able LEDS and easy ways to drive them for clothing or jewelry items.

I really wanna do this as I have no job and im disabled but dont get disability anymore (long story) I will be able to afford all the components and the manufacture of the PCB's though.

Any extra advice is also appreciated.

If I go SMD im thinking of using these
https://www.adafruit.com/product/1655
Nitrousoxide:

--- Quote from: Astaldoath on April 04, 2018, 04:11:19 am ---Main points:
SMD or Through hole
Maximum Brightness
Diffuse or not diffuse

--- End quote ---

Use SMD, most people use SMD these days for a good reason. You're able to increase layout density and as scary as they look for a novice, they are actually unbelievably simple to solder given the correct tools. On that note, the 888d is fine for SMD work, it all depends on the tip, flux and solder you use.

As for LED's, from my personal experience, you would want to diffuse if the diode is going to be facing anyone's eyes, they get REALLY annoying due to their eye-piercing nature. (Of course, if you diffuse you will lose intensity)
Using Digikey to select a part, I too arrive at: https://cdn.sparkfun.com/datasheets/Components/LED/WS2812.pdf

More importantly, You will also have to take into consideration other key design aspects that you have neglected to mention such as:
- Controller: PIC? AVR? 8 bit micro?
- Power supply: Batteries? boost converter? (they are 6-7 volt LEDs)
- Interface: Buttons? Sensors? USB? One time programmable? (You did mention a remote, but not any specifics)
- Misc: Any other features that you might need?
Ian.M:
WS2812 and similar intelligent LEDs aren't particularly energy efficient.   They typically use a PWMed constant current LED driver on the chip, and any excess voltage above the LED Vf + minimum headroom for the constant current circuit just turns into heat.   Therefore its desirable to operate them as close as possible to their minimum rated operating voltage of 4.5V as you can.

Powering them compactly is an issue - a single coin cell doesn't have enough voltage, and two would be on the high side of what's permissible.   Also with a nominal current of 20mA per LED die, each can draw 60mA all on, so the total power required adds up quite rapidly.   One approach would be to power it from a single 18650 cell USB powerbank.   Micro USB plugs aren't particularly compact so it may be best to hack a retractable (self-windup style) USB lead cut off the end and solder the wires directly to the back of the board, with a dab of epoxy for strain relief.

As to what to control it with, well for a one-off you probably want Arduino compatibility for easy 'hackability' by non-nerds.   Use a USB capable ATmega that's supported by the Arduino IDE, and you wont have to mess with USB interface chips, or building a custom remote, or programming cable.   You may want to consider a Bluetooth module if you think your coding skills are up to writing a phone app to control it.  If not, then one or two buttons to select an effect from the choices given by the sketch that has been loaded into it would be the way to go.  They could either be physical switches - miniature tactile button switches, or capacitive touch pads directly handled by the ATmega.   


Don't forget pads for AVR ISP so you can initially flash the ATmega with an Arduino compatible bootloader.
Astaldoath:
Im thinking of using either like a micro arduino, or a teensy from adafruit, or just building something built in that can drive the LEDs which i would have to research.

BTW here is my crappy image of my idea

Now bear with me its done in paint i could do it better on paper.

When i say seperate pcbs as the green part, its not going to be seperate, i plan on having it all 1 PCB but cuts like a gap between them I dunno why I just think it would look better like that, if the company would have to charge me a lot more then ill just do a solid heart, without sizing cutouts so it looks like a heart inside a heart inside a heart inside a heart.  If i can do the cutouts I think 6 separate sized hearts going from the biggest size to the solid little one in the middle would be what I would be planning on doing. Im gonna post on adafruit and see which of their boards would be best to control the LEDS with. Either way, cut out or not I want to place the LEDS in a heart pattern around it so I can do one outline in 1 color, another color up to 6 seperate colors at once, and either have a IR remote to change the color. Like some of the LEDS strips that are prebuilt use. I also will have to figure out the power supply part to power all the leds. Im not sure how many I plan on putting on each ring of the heart im thinking between 10-20 LEDs so it will be bright enough.



However if all the color changing ect.. causes me to much grief at first I will just use set rows of LEDS, like Red, green , blue, purple, orange (if they dont have the color i want in the brightness i want ill use RGB leds and im talking through hole this time mind you, if the SMD and such gets to be to difficult atm, then I can upgrade as I learn more)


Here is my crappy image idea and it does not do the idea i have any justice at all i just cant use paint lol









This may give a better idea, something like this, in heart shape, and 1 heart inside each other but still being a solid PCB just with air gaps around the outside like the colored LED ring in this image


hugo:
Something to inspire you:

https://dmitry.gr/?r=05.Projects&proj=22.%20Vday%20Heart
https://dmitry.gr/?r=05.Projects&proj=13.%20Greyscale%20LED%20matrix%20pendant%208x8

BTW are you in love?  :)
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