Learning process...one more option on Tx-Encoder board

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Tobe
Posts: 665
Joined: 16 Feb 2018, 06:19
Location: Varberg or Stockholm, Sweden

Learning process...one more option on Tx-Encoder board

Post by Tobe »

Many things are quite new for me but that doesn't make any difference so I have to learn new tricks and KiCad and JLCPCB is something that ended up on my bucket list. As I work for my bread & butter I normally keep on the side something that allows me to clear my mind, sometimes it's just a stroll or otherwise some kind of project that helps me evolve in my field...model airplane or even better professionally as a product developer.

So I'm going to share one "new" learning project with you all and here it's about to make my "own" encoder in shape and size to fit my needs. What I have done is to build a board that depending on software used it can be used or with a regular PPM driven RF module or the nRF24+ PA module.

The board is intende to be mounted on top of a battery box like in some Kraft Tx and the size is 100 x 35 mm

What I have done is to design this board so I can experiment and learn from it and eventually end up with a more optimized board. The design and feature are "borrowed" all the way around...and I decided to have the option to mount Rate & Expo pots directly on the board.

Possible more to come.


...and yes, I sure sleep my 8 hours like baby every night if you wonder

Cheers Tobe
Tx 328P nRF24+.jpg
Cheers,

Tobe
WernerL
Posts: 27
Joined: 22 Jan 2020, 02:30

Re: Learning process...one more option on Tx-Encoder board

Post by WernerL »

Nice board!

KiCad is just fantastic for us hobbyists; and the boards from JLCPCB are amazing for the price.

Mounting holes: yeah! So many people forget those...
Great choice of GND / VIN / GND on the battery input! No more blown boards because you plugged the battery in wrongly!
Wide traces for power lines: superb!

A few ideas, if I may:

I do not see any capacitors on the input of the voltage regulators. Usually LDOs want to have something like 1uF on the input for buffering of transients.

I assume you will put an additional capacitor directly on the nRF24 module power supply. If not, then I would suggest moving the larger output cap on the 3.3V LDO closer to the nRF connector. It may also be a good thing to make that capacitor quite large, something like 10..47uF.

It may be worth investigating whether it is possible to swap the locations of the 3.3V LDO and the programming header. Then the programming header would be closer to the 328P, and the 3.3V LDO closer to the nRF24 connector.

I am surprised that you put the GND of A0..A7 and D3, D7, D8 towards the inside of the board. I would assume routing would be significantly easier when GND faces towards the board edge. and the data pins towards the 328P.

Silkscreen: I would rotate the annotation on D0 and the battery connector by 90 degrees. (KiCAD: select the silkscreen layer, select the text, press R to rotate). This way they are easier to read.
The +3V label on the nRF connector overlaps the copper, so it will be cut-off on the final board.
The "x" markers on the LEDs are a bit confusing, since they seem to indicate the Anode of the LED. Maybe change them to a "+"? Usually board designers mark the Cathode of LEDs, and the KiCAD footprint has already a marking of the Cathode: the closed outline on short side.

The smallest caps look extremely small: 0402? Since space is not a concern 0603 or larger may be easier to solder -- at least for me, being half blind and jittery.

great job as always, Werner
Tobe
Posts: 665
Joined: 16 Feb 2018, 06:19
Location: Varberg or Stockholm, Sweden

Re: Learning process...one more option on Tx-Encoder board

Post by Tobe »

Appreciate your input and you have good points :D

Many issues are just how the boards are designed in the products I'm designing at the moment.
Unfortunately my hands are not as they were so I leave it to JLCPCB to install all SMD.

Rome was not built up in a day...and not being to young anymore I need a longer takeoff 😫 distance but I still get airborne thankfully and enjoy every moment of it.
Cheers,

Tobe
Tobe
Posts: 665
Joined: 16 Feb 2018, 06:19
Location: Varberg or Stockholm, Sweden

Re: Learning process...one more option on Tx-Encoder board

Post by Tobe »

Version 2.0 is up and running on my :D breadboard
Tx 328P nRF24+Ver_2_0.jpg
Cheers,

Tobe
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Wayne_H
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Location: Temora, NSW. Australia
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Re: Learning process...one more option on Tx-Encoder board

Post by Wayne_H »

Superb ;) :ugeek:
Cheers,

Wayne
Once a Retrobate, always a Retrobate............ ;)
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tiptipflyer
Posts: 393
Joined: 16 Feb 2018, 22:49
Location: Germany

Re: Learning process...one more option on Tx-Encoder board

Post by tiptipflyer »

Excellent work Tobe, as usual.
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stuart mackay
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Joined: 01 Mar 2018, 10:38
Location: Swaffham, Norfolk
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Re: Learning process...one more option on Tx-Encoder board

Post by stuart mackay »

Wow Tobe, was discussing this with Mike today and i think having the rate expo pots on the board is a good idea as most tranmitters get very "busy" on the upper half and top surfaces and not having to mount bulky pots externally is a good idea in my opinion.
You have my admiration & respect, Sir! 8-) 8-) 8-) 8-) :ugeek: :ugeek: :ugeek:
Tobe
Posts: 665
Joined: 16 Feb 2018, 06:19
Location: Varberg or Stockholm, Sweden

Re: Learning process...one more option on Tx-Encoder board

Post by Tobe »

I quite often install the Rate&Expo pots on a separate PCB that I mount inside the case in a suitable position.
Here's the inside of my "almost fully DIY Tx"
20210404_082610.jpg
20210404_082048.jpg
Cheers,

Tobe
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_AL_
Posts: 160
Joined: 17 Feb 2018, 01:09
Location: Sydney Australia

Re: Learning process...one more option on Tx-Encoder board

Post by _AL_ »

I've done the same with most of mine. A small vero board with the expo & rates on trim pots..
One of my Kraft's had holes drilled in the case by the previous owner so the pots sit behind that. The others are accessed by removing the back of the case.
Each to their own but I like the outside to look clean, regardless of how messy it is inside.
Tobe
Posts: 665
Joined: 16 Feb 2018, 06:19
Location: Varberg or Stockholm, Sweden

Re: Learning process...one more option on Tx-Encoder board

Post by Tobe »

Hope you all enjoyed Easter holiday.
I was waiting for a DHL from JLCPCB and today was my lucky day....

I'm fully aware the video is terrible but it shows my Encoder up and running with nRF24+ ,thanks to Phil's lockdown project, with the 3,3v supplied directly from the encoder board as it's equipped with a separate voltage regulator for 3.3V.

It's a learning plattform but eventually I will get there.
In the video I'm using 4 of my DIY ProPo servos with the amplifier based on Mike K sketch adapted to work on my own 328P platform with a DRV8838/DRV8835
...here follows a preview of what will come next
Tx 328P nRF24A+.png

When I'm done with all this hopefully I will be able to hit the flying field
Attachments
20210406_201740.jpg
20210406_204510.jpg
Last edited by Tobe on 06 Apr 2021, 19:47, edited 5 times in total.
Cheers,

Tobe
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