SEEEDpod EDC Lite

Description

The impetus behind the EDC Lite is to create the absolute lowest barrier to entry possible for achieving a fully functioning Meshtastic node. No soldering is required, and there are no special filaments…or hard to find fasteners…or anything else to buy! All you need is your printer (most public libraries now have 3d printers, fyi), some super glue, and a Seeed Studios nRF52 dev kit. You can catch them on sale for around ten dollars, and the case itself only uses about fifty cents worth of typical filament, so you can make these for ten dollars on the low end and fifteen on the high end, making them one third to half the cost of other similar nodes.

This is a great option if you just want to dip your toe into Meshtastic without spending a lot of money, or if you’re trying to outfit an entire group of people on a budget.

There is no battery or GPS integrated into these units, so you will power the node via USB-C cable, either from your device or a power bank. A smart device or computer is needed to operate these nodes anyways, so it’s only natural to power the node from your device, as well as take advantage of your phone’s GPS. Basically the only downside is having the cord, which is admittedly somewhat awkward, but the nRF52 boards are so efficient that you won’t notice any affect whatsoever on your phone’s battery life.

With the USB-C cable plugged in (or a silicone cover installed), the housing gives IP-65 dust and water protection (dust and splash proof), which is as good or better than your phone. The only catch is there are two little holes in the housing (one for the reset button and one for the LED indicator light), and you can cover those with tape or plug them with a little hot glue, silicone, etc. That, a quick rattle can paint job, and keeping the device oriented vertically while in use will make it resistant to even prolonged rain. You may also semi-permanently install the USB-C cable by sealing its connection with silicone, which, in addition to the previous mods, would make it fully IP-67 waterproof.

Notes on version:

If you’re unsure whether to get the V1 or V2 files, the V1 uses the little PCB antenna that comes with the devices from the factory, and the V2 uses an IPEX to SMA adapter so that you can use an aftermarket antenna (such as the very popular Muzi Works whip antenna), which will increase your range.

Is the V2 always better? Not necessarily. The PCB antenna that’s included with the devices is actually going to be better in some instances than a higher gain external antenna, specifically in situations where you’re close to another node. These lower gain antennas are much less directional than the higher gain ones, so it doesn’t matter much what orientation it’s in (such as thrown in a backpack), whereas the higher gain antennas require some deliberate placement since they’re more directional (e.g. the antenna needs to be kept vertical). Obviously, the PCB antenna also has a better form factor. So to summarize, if you’re using the devices at close range, the V1 is the better choice from a cost and ease of use perspective, but if you’re trying to maximize range, the V2 is absolutely the way to go. And if increased range is the goal, spending your money on a good aftermarket antenna is always money well spent, because even expensive nodes come with cheap antennas, so it’s better to have an inexpensive node with a limited feature set like the nRF kits with a really good antenna, vs having a really expensive feature packed node with a cheap antenna.

If in doubt, I would say get the V2 and put some cheap stubbies on them, which will give you a little more performance than the PCB antennas at a really low cost, without changing the form factor. And if you’re not happy with the range you’re getting out of them, you then have the option to easily upgrade to a nice whip antenna.

Notes on print settings and materials:

I recommend printing at 0.15mm layer height (0.2mm first layer) with a standard 0.4mm nozzle. No supports are required, but I would generally recommend a brim for the antenna housing, and, depending on filament, build plate material, and bed prep, you may require a raft.

This design is 100% dependent on glue, so namely you want to use a material that glues well, which is primarily going to be PLA and ASA, and which will generally preclude PETG and similar materials from being good candidates. PLA and ASA are both highly, highly compatible with run of the mill super glue, so they’re obvious choices. That said, there are special adhesives for PETG, and while they’re expensive, the cost per unit would still be relatively low if you were gluing a lot of PETG. The tl;dr is I would recommend ASA, but if your printer can’t handle ASA, then HTPLA is a good option, as well. Even run of the mill PLA is fine, though it will warp in direct sunlight, so you may have to replace the housing often, which could get annoying. The good thing, however, is that the design doesn’t place any load on the components since there are no fasteners, so it lends itself to PLA in that regard. The antenna housing requires some special consideration, though, as different materials (and any pigments or fillers) affect antennas to different degrees. Pigments like carbon and fillers like carbon fiber are bad about detuning antennas, but organic pigments and fillers like glass are basically RF neutral, so, for example, CF filled materials are a poor choice, and black filaments in general might be best avoided, but a colored glass filled material should be just fine. A natural ASA is a great safe option, all else being equal.