MiniX- Faketec a more compact variant of the Faketec V4 with additional freatures

[lupusworax]

Finding a very nice design of a more compact design of the FakeTek V4 on a chinse website, I ordered some PCBs and build them. Apart from a few flaws like different hole diameters, wrong labeling or swapped ports I was able to make it run successfully, resulting in a tiny node. It already featured a mosfet for gps , as well for the buzzer that is already implemented on the pcb directly.
I wanted to push this board further and came up with the new layout.
Thanks to Judith and Jing Guo for the naming of the board!!

Labels were corrected and updated, a third mosfet, pull down and connection pads for a vibration motor were added.
3 GPIOs broken out for the navigation switch that also found a spot directly on the PCB
A bridge for shorting the boost pads for 300mA charging.
Broken out LED connections with series resistance also for notification purposes.

The boards are on the way and once delivered and tested I will post them here.
They use all the same parts the Faketec V4 also uses, only difference is the 10K pulldown resistors now being 0603 instead of 1206.
The navigation switch compatible is the following type ( both of them work)

The buzzer directly placed on the pcb is this one:

and can be found here: https://de.aliexpress.com/item/1005003924871370.html
With the original design I was able to build really tiny builds and I already love them, cant wait to get the boards and design a new small case including everything Meshtastic has to offer.

Ready for produktion Gerber file can be downloaded here: https://1drv.ms/u/c/2c67368a838f1199/IQB89iT2BxlJTZBfzbcJJwn1Afu9cAv_TWSMusc-lJVZHvE?e=JOkbxV

BOM:
https://1drv.ms/x/c/2c67368a838f1199/ET8Aq4KHNdJKmKTWteWQwgABc_6ukWMk-eV6PkVx-6z_GQ?e=gUImLv

Project file:

https://1drv.ms/u/c/2c67368a838f1199/EbxlATQF34ZAvzDpt8qt9sYB8zC7f3cMg0Ks0V4nG6iBOg?e=y9CM3y

[JudithWang25]

Looking forward to your design!

[acodexm]

Awesome job! I was thinking of doing the exact thing! Would you be able to share the project files? I'm very cuirous on how the pcb is designed double side.

[lupusworax]

Awesome job! I was thinking of doing the exact thing! Would you be able to share the project files? I'm very cuirous on how the pcb is designed double side.

added the project file.

[jem0n]

would 0805 resistors fit or only 0603?

[lupusworax]

0805 should totally fit, especially if you work with hot air, with a soldering iron and a small enough pointy tip its also a non issue, so yeah it works!

I even used a mixed set, using 0805 for the 10K pulldowns and only a single 0603 for the LED series resistor ;)

[mofosyne]

@lupusworax just a heads up that the project link in https://github.com/lupusworax/MeshtasticMini-ultimate- is incorrect (is it ment to be kicad source?)

Also wondering if you would find it useful for you to adapt the 'tray sled' shown below which is written in openscad... to act as a holder for MiniX for easier soldering on both sides?

https://www.printables.com/model/1427053-keepteen-d5-lora-solar-dual-tray-sled-heltec-t114

Plus maybe you can consider if it's an option for a 'screwless' mount of the pcb in your next case design.

Also consider adding support for mounting a rotary encoder if possible (e.g. is pullups required for rotary encoders? Some tutorials above seem to suggest so.), the pinout can reuse the current up/down/select encoder but have a different footprint for the rotary encoder. (Might be possible to support both footprint by overlaying it?)

[lupusworax]

@lupusworax just a heads up that the project link in https://github.com/lupusworax/MeshtasticMini-ultimate- is incorrect (is it ment to be kicad source?)

Also wondering if you would find it useful for you to adapt the 'tray sled' shown below which is written in openscad... to act as a holder for MiniX for easier soldering on both sides?

https://www.printables.com/model/1427053-keepteen-d5-lora-solar-dual-tray-sled-heltec-t114

Plus maybe you can consider if it's an option for a 'screwless' mount of the pcb in your next case design.

Also consider adding support for mounting a rotary encoder if possible (e.g. is pullups required for rotary encoders? Some tutorials above seem to suggest so.), the pinout can reuse the current up/down/select encoder but have a different footprint for the rotary encoder. (Might be possible to support both footprint by overlaying it?)

Project link updated, thanks.

A Rotary encoder directly on the PCB would be a bit overkill as it is pretty big compared to the nav switch that levels evenly with the RA62 module, you can directly use the 3 gpios from the nav switch on the rotary encoder to connect it externally.
The screw holes are optional to use of course and only on one side. Using the Nav switch on the pcb one of the two holes already gets disabled. The board as is can be easily clipped or sloted into whatever design you come up with, I dont think the screw holes are considered a problem.
An extra sled for the pcb would add a lot of bulk to the board, as I plan to build a lot of different small micro nodes and builds I dont wanna use an additional frame on the board now that I finally have it as small as possible.

[lupusworax]

Managed to cram all of it in an upgraded Bumblebee build. whaaaat a shitshow, this build almost made me cry XD gonna need to update the design to make it easier to build.......but its a difficult one thats for sure!

[lupusworax]

"Mighty-tiny" design can be found on my printables page:
https://www.printables.com/model/1500114-meshtastic-xmini-faketec-mighty-tiny

[mofosyne]

Would it be possible to also add an optional power switch to your design? Might be helpful to switch it to radio silence mode.

[mofosyne]

Btw, I wonder if it's worth using a DRDC3105 to reduce the BOM count for driving the buzzer and vibration motor?

https://www.diodes.com/assets/Datasheets/DRDC3105.pdf

https://www.digikey.com.au/en/products/detail/diodes-incorporated/DRDC3105F-7/3028437

This basically is a BJT with:

• an base current resistor of 1K
• an base pulldown resistor of 33k
• an base reverse polarity protection diode
• an output 6.6v zener diode (for coil flyback protection)

Will a BJT be a suitable replacement in this context? I know a mosfet is faster responding so is better for PWM, but I doubt we are driving this too fast anyway even for the buzzer.

There is a SOT26 version which includes two in one, so that will also help reduce the parts count further.

[lupusworax]

You mean to power it off completely? or just shutting off the buzzer?
For someone getting into the whole faketec thing it probably is an option to use a DRCC3105 in an updated design, but as my build is based on the faketec V4I wanted to keep using parts that come from the original V4 variant and faketec build in general.

[jem0n]

are there any 3d-printed case for the minix that's more manageable (and not having to resort to lacquer wires) with regards to wiring and not as cramped internals?

[lupusworax]

are there any 3d-printed case for the minix that's more manageable (and not having to resort to lacquer wires) with regards to wiring and not as cramped internals?

So far as the board is pretty "fresh" I only got the "Mighty-tiny" and the "Tiny-tiny" the later being a lot easier to build. but for now I guess not a lot of different other cases. There will be others eventually of course.