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Oct 12, 2017, 08:44 AM
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Discussion

uESC World smallest 1S BLHeli_S ESC


Inspired by fishpepper micro designs, I thought that it should be possible to make even smaller ESC if to use double mosfets.
I found MicroFET 1.6X1.6mm thin package that can work at 2-3A with proper cooling.
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But in such a size there is not possible to make 4in1 ESC, because of package heat limits.

So, having the specs of mosfets lets make a board...
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Board size is 6.5X10.1mm. Not bad I think. The calculated weight is about 0.2gr.

Mine solder paste is finished, so I used 3D printer extruder heater to solder these ESCs.
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  1. With iron apply solder to the PCB and mosfet pads. Use a flux.
  2. Preheat the heater to 210-220C and then put PCB on it.
  3. with tweezers put the mosfets on PCB and add a bit of flux. Mosfets will align themselves.
  4. After inspecting their placement with magnifier, switch heater off.
With a lot of flux, soldering of this mosfets is quite easy. I think, I like this method more that using hot air gun for example.

After flashing it with BLHeli_S and frying some mosfets, finally I've got it working
First test World smallest 2A brushless ESC (0 min 32 sec)

To be safe I used firmware with timing 30 (with 10 mosfets were not happy).

All 4 came out 0.8 gramms. Exactly what I expected!
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I'm also developed 11X11mm F3 FC for this project. But this is another story...

If you think you want to try it make yourself, here is the BOM (Mouser codes) and schematic:
Code:
3 pcs of FDME1034CZT: 512-FDME1034CZT
1 pcs of EFM8BB21F16G: 634-8BB21F16GCQFN20
1 pcs of 0603 47uf cap: 81-ZRB18AR60J476ME1L
1 pcs of 0402 10uf cap: 81-GRM155C80J106ME1D
1 pcs of 0402 100n cap: 81-GRM155R71A104KA1D
4 pcs of 0402 1k resistor: 754-RR0510P-102D
3 pcs of 0402 10k resistor: 754-RR0510P-103D
All passives are 0402 size, except one bigger cap. It is in 0603 size.

Schematic: uESC1S2A

Components placement:
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PCBs can order at OSHPark (0.8mm board thickness). This board slightly different from I have on the picture. It is next revison, bit smaller and better power lines routing.
If you want to see alternative boards, see second post...

Flashing
Firmware: O-H-15
Please refer to this post and this for more information

Pinout:
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Connections:
Arduino Uno
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Arduino Nano
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And please remember, you should not power the uESC with something higher than 4.2V (1S). For example, while flashing with Arduino first time, do not power the uESC from the Arduino 5V, but use 3.3V or 1S battery.

(28.10.2017) Also in development 4in1 X shape board
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(18.12.2017) Seems this is not very good design (see here)

(11.12.2017) Here is 4in1 1S 4A square shape board with 12mm holes distance
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Description: 4A 1S 4in1 12mm versionName: Components4in1square.png
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Description: 12mm holes distance
PCB at OSHPark

4in1 BOM
Code:
12 pcs of SSM6L61NU: 757-SSM6L61NULF
4 pcs of EFM8BB21F16G: 634-8BB21F16GCQFN20
8 pcs of 0603 47uf cap: 81-ZRB18AR60J476ME1L
4 pcs of 0402 10uf cap: 81-GRM155C80J106ME1D
4 pcs of 0402 100n cap: 81-GRM155R71A104KA1D
16 pcs of 0402 1k resistor: 754-RR0510P-102D
12 pcs of 0402 10k resistor: 754-RR0510P-103D

Here is first Australia build of uESC (Thanks to Pedro and Ian444)
uESC via MultiWii GUI motor tab & Spektrum DX6 (1 min 6 sec)
Last edited by nppc; Dec 28, 2017 at 04:56 AM.
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Oct 12, 2017, 08:44 AM
Registered User

Alternative boards


V2.1 More neat version
You can order from OSHPark a bit different board, It is smaller and I like it's look more
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Description:
Size: 6.4X9.8mm
Components are the same as in the first post.

Also another version with different mosfets
Specs are:
Voltage: 1S (max 4.2v)
Current: 2A
Size: 6.2X10.2mm
Weight: about 0.25gr

The mosfets are AO6604. All other components as in base version.

OSHPark
Last edited by nppc; Dec 28, 2017 at 06:37 AM.
Oct 12, 2017, 10:25 AM
Copper Copter


Dang wish I had the equipment to do stuff like this.
Oct 12, 2017, 11:12 AM
Registered User
If you're going to have your own pcb fabricated...wouldn't it save weight and size to just do a 4 in 1?

At least for quads that would seem to make the most sense to me. For other purposes though this looks pretty cool for micro indoor planes or non-quad copters.
Oct 12, 2017, 04:43 PM
more speed and less weigh
Wow that's awesome
Oct 13, 2017, 02:24 AM
Registered User
Quote:
Originally Posted by cellsafemode
If you're going to have your own pcb fabricated...wouldn't it save weight and size to just do a 4 in 1?
It would be really nice to make 4in1 in size, let's say 15x15mm (hole distance 12x12mm).
With current mosfets I'm using, it is not possible I think. They need proper cooling to handle 2A. I also have a version with bigger mosfets (2x2mm footprint), maybe they will work without cooling? I tested only 2A and I had burned mosfets without airflow on them.

I think, the better way is to put on one PCB (cross form) mine small FC 11x11mm and these 2A ESC's. Then it will be something similar to PCB of Eachine H8, but brushless, betaflight compatible, smaller and lighter. Here is the idea in "photoshop" compiled.
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I also have developed simple OSD that weights less than 0.1gr and smaller than one ESC. Then only need to connect RX (like pepperfish uSKY) and you will get lightest setup ever.
Last edited by nppc; Oct 13, 2017 at 02:52 AM.
Oct 15, 2017, 04:10 PM
Brisbane, Australia
Nice work! The limiting factor of a FET is the milliohms resistance (on-resistance) when turned on at the current you want and the gate voltage it is given. Power dissipated by the device is current^2 x on-resistance. If the dissipated power exceeds the device's power dissipation limit listed in the specs, then it will overheat. For the same physical size, the FET's with the lowest on-resistance will handle the most current. Also the FET with the lowest on-resistance will deliver the most power to the motor. There are so many FET's available, it can be a never-ending and tiring search to find the best one for the application. But maybe you knew all that, if so, please disregard my comments.
Oct 15, 2017, 04:22 PM
Fan of just about anything RC
SoloProFan's Avatar
That's some impressive miniaturisation.
Oct 16, 2017, 01:55 AM
Registered User
Quote:
Originally Posted by Ian444
Nice work! The limiting factor of a FET is the milliohms resistance (on-resistance) when turned on at the current you want and the gate voltage it is given. Power dissipated by the device is current^2 x on-resistance. If the dissipated power exceeds the device's power dissipation limit listed in the specs, then it will overheat. For the same physical size, the FET's with the lowest on-resistance will handle the most current. Also the FET with the lowest on-resistance will deliver the most power to the motor. There are so many FET's available, it can be a never-ending and tiring search to find the best one for the application. But maybe you knew all that, if so, please disregard my comments.
You are absolutely correct!
I would like to see a good mosfet in this size (1.6mm X 1.6mm). If you will find something, please post it here. So far I see, that the variety of this kind of mosfets are quite small. Thank you!
Oct 23, 2017, 04:17 AM
Registered User

Successful flight test


Yesterday I made first real flight with these small DIY uESCs. They are working well. Only mine concern is the motors. They are really bad in quality. I have a lot of vibrations from them.
I have not yet installed camera on mine micro quad, because I'm still waiting for 0.4gr RX.
The test was made with big R-XSR Frsky receiver.
With 300mah battery flying weight was 23gr.

Also don't have any video, because of lack of hands.
Oct 23, 2017, 05:52 AM
Registered User
TyKKaH's Avatar
Impressive!
Oct 23, 2017, 10:04 AM
Copper Copter
Quote:
Originally Posted by nppc
Yesterday I made first real flight with these small DIY uESCs. They are working well. Only mine concern is the motors. They are really bad in quality. I have a lot of vibrations from them.
I have not yet installed camera on mine micro quad, because I'm still waiting for 0.4gr RX.
The test was made with big R-XSR Frsky receiver.
With 300mah battery flying weight was 23gr.

Also don't have any video, because of lack of hands.
Oct 23, 2017, 02:03 PM
Registered User
Quote:
Originally Posted by nppc
PCBs can order at OSHPark (0.8mm board thickness). This board slightly different from I have on the picture. It is newest revison, bit smaller and better power lines routing.
Orders from OSH Park normally come in lots of three nppc so what is the best way to get the four boards required to build one quad please Also could we get a full parts list seeing as you do not specify the minimum specs of the passives. Links to a major supplier or MPN would be very helpful please seeing as some of us with less technical knowledge on parts selection could end up getting parts not suitable. Thank you for a great little project and for sharing your work.

Last edited by Pedro147; Oct 23, 2017 at 02:19 PM.
Oct 23, 2017, 02:21 PM
Registered User
Sure, tomorrow will compile some BOM. You can order x3 (9boards) at oshpark. These boards so crazy cheap in this size... But I also have another design more hand solder friendly. But not yet received the PCBs...
Oct 23, 2017, 03:14 PM
Registered User
Quote:
Originally Posted by nppc
Sure, tomorrow will compile some BOM. You can order x3 (9boards) at oshpark. These boards so crazy cheap in this size... But I also have another design more hand solder friendly. But not yet received the PCBs...
Thanks a lot I might wait for the second version. I assume that the BOM will be the same. I am looking forward to giving these a try


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