I have started venturing into building my own saber. I recently got a 3D printer and have a good design background (some architectural and mechanical draughting ±10 years or so, but am now in the App dev space) and am keen to start designing my own hilt etc.
However, I am a total noob at the other side of this sort of stuff and would appreciate some guidance as I go along. Build plans (so far):
Proffie 3.9 (on the way)
40mm Speaker (already got the resonance chamber dialed in - sounds fantastic)
Will design and CNC tube-laser the outer hilt, with internal chassis etc. 3D printed at home
Got a INR21700-P42A Molicel 3.7v 4200mAh (40A continuous) unprotected battery on hand. The 40A is overkill, but it’s the same price as all other locally available batteries in a similar league. Yes, I know that unprotected batteries are not ideal. However, should it be a neccesity, I do have a 1S 30A 3.7V BMS I could try and build into the overall package.
Got some illuminated buttons for the on/off. These are from other cheap sabers i’ve bought over the last 2 years.
As per the above, I also have a few hilt-side 10 Pin Pogo connectors. Some concerns about this below.
I also have a PD65W Fast Charging Module (5-12V 3A) with Type-C so as to assist with charging the battery faster than a 0.5A onboard or 1A typical modules.
For now, I have a 36" 1inch (92cm/25.4mm) thick-walled translucent white polycarbonate tube for the physical “blade”.
Hope i’m not missing anything.
Anyways, I think it’s probably best to address my 1st concern which is power/current.
From what I understand, 4 LED strips at 132 LEDs per strip (528 total LED) would draw the following currents with the respective colors:
Red: 528 × 0.02A = 10.56A
Green: 528 × 0.02A = 10.56A
Blue: 528 × 0.02A = 10.56A
White (RGB): 528 × 0.06A = 31.68A
Mixed colors: 528 × 0.04A = 21.12A
Now, I would never run full white, but there would be very slight spikes with certain affects I suppose. I can’t seem to find a solid set of copper battery contacts with enough thickness and surface area to safely pull ±20A, so I will likely just be making my own with copper bolts and a spring, much like these. Am I on the right track here or overthinking this? This would be factored into the 3D printed modular chassis.
Still on the subject of current - I am not at all confident in 10 pin pogo connectors being able to push ±20A. At best, these pins probably transfer about 1A each, so it just doesn’t feel ideal to me. Please correct me if I am horribly mistaken - but if not then I need a better solution to allow more amps to the quad-star PCB.
There’s also the matter of sufficient and realistic wire thickness. All the maths ideally points to 12-14 AWG which is just insanity for this kinda’ setup, not to mention the tiny wire-to-board soldering that needs to take place. Any suggestions and corrections are extremely welcome.
I feel that the power/current issue is a key hurdle to get over and then I can start vomiting out more questions if needed.
I seriously appreciate any help and expertise from you guys! Thank you.
I don’t think I’ve ever seen a neopixel that draws the full 60mA that the datasheet say they may, and they certainly do not draw 0.06A when you give them 4.2 volts. (Maybe they do if you give them 5 volts?) It will vary a bit, but my experience is that each pixel draws ~35mA at full white, which makes the math a little easier to deal with, as 35mA * 528 = 18.48A .
In theory, the pogo pins themselves are rated for 3A each, that might be a bit optimistic though since the contact point is very small. I have a blade with 529 3535 LEDs in it, and I have a 11-pin pogo pin pcb, and I have not noticed any heat there. (But the pixels themselves get warm after a little while, with this many pixels you’ll want to give the blade a break every 10 minutes or so so you don’t melt it.)
The battery thing seems like overkill to me, but I can’t say for certain, because my battery is just soldered in.
As for wires, there are no hard and fast rules, it’s just about how much heat you’re willing to tolerate. In my saber I used AWG 18 for the major power path if I remember correctly. The shorter the cable is, the more you can get away with. As long as it stays cool, it works.
One tip for making the wires easier to fit in the saber is to buy teflon-coated wires rated for the lowest voltage possible. (which is usually 300 volts) These wires will have much thinner coating, which can save a fair bit of space compared to regular plastic-coated wires. Just beware that the teflon-coated wires are usually a bit stiff.
Anyways, long story short, I recommend starting with actually measuring how much power your pixels use. Then we can get into the details about what size wires and connectors you actually need.
The infamous Prof! Thanks for the advice and feedback.
Yeah, I don’t have the official NPXL connector I think. I have ones that come off some LGT-style blades off AliExpress, so I can’t really estimate if the pins used can handle the same current… which really sucks for me I guess lol.
I’m not a fundi on anything electrical, so as noob I wouldn’t really even know how to test anything. I assume with a multimeter and a source wired to the LEDs. I’ll figure that out.
I suppose you don’t have a way to tell for sure - however, I would think any of these spring style connectors use the same Mill-Max pins because they are already in production and fairly cheap.
A single pin is rated for 2amp continuous and 3amp peak.
I guess you could desolder them and replace them with known Mill-Max pins to be sure.
Thank you.