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First character testing - It works!

A project log for MOLBED Modular Low cost Braille Electronic Display

A project that I started in 2014, aimed to develop a low cost and modular refreshable Braille system

MadaeonMadaeon 07/23/2016 at 10:102 Comments

In this test we spell in Braille h-a-c-k-a-d-a-y (correctly, I hope :) It works, finally!

Lot of things still to be improved, coil optimization for faster refresh and state change, smaller overall size, higher holding force, design the PCB for the line control. Each pin has just one coil driven by H-bridges, that will be integrated in the line PCB.

Interesting thing is that the cost for a single character will be very low, since this project is designed with the goal to use parts as common as possible and as cheap as possible.

Each character consist in a pcb, connectors to the Line PCB, the body and magnet holder and top plate (injection molded if the project will raise some funds), 2 M2 nuts an 2 magnets and some enameled copper wire.

It is almost impossible to get an even lower part count!

The next steps will be optimization of the single char and designing of the character / line PCB. An automatic coil winder is already being designed, and I am also evaluating to build a micro-factory where the pins are automatically assembled, more on this in the next updates!

Feedback are also important, we are now getting in contact with Italian associations for visually impaired people, their feedback will help refining the project.

When the design will be refined enough, I'm going to design a full Braille tablet, and it may feature 2G connection via a Fona module, color recognition, eBook reading, maybe a modular design too...

Discussions

Madaeon wrote 08/03/2016 at 12:32 point

Hi, thanks for your suggestions!

I would like to discuss your points and see what you do think about it.

-I use one L293DD every 2 coils, and the cost for 100 pieces or more of L293DD should be ~1$ ordered from chinese supplier. If I were to build a discrete H Bridge I am not sure that 8 transistors and 8 resistors will cost very less than a L293dd; but I may be wrong and I will request come quotations to verifiy this.

-Do not worry for feature creep; as you can see, I am designing and testing each part, and going to the next only when it works; but I must have at the same time a "long range goal", a direction, or final goal. And it is useful also if you have to make a business plan or search for investors (even if I am not going to do it at the moment). And I think that a tablet-like device would be a great implementation of my Braille system. All the other extras (2G, color recognition) are just ideas that I will collect during the way and may be or not be implemented when the time will come to design the final device.

-You are right, I am going to contact the national italian association for visually impaired people for support, and involve them in the design, as soon as I have at least an 8-character prototype. Local governament funds here are not very easy to get, better chances with european funds (but requires a LOT of documentation), or big contest/challenges as the Hacakday prize ;)

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Trevor Johansen Aase wrote 08/01/2016 at 16:33 point

Very nice! a few points that may help out:

- A discrete H-bridge would be cheaper than an L293, at $2/coil that's probably your highest cost. You could made a board sandwich with the lower PCB have the discrete drivers and the upper as your digits as you have. I would keep them separate as the digits will wear out and that would lower replacement costs.

- "I'm going to design a full Braille tablet, and it may feature 2G connection via a Fona module, color recognition, eBook reading, maybe a modular design too..." You are already suffering from feature creep, lol. I whole heartedly recommend you get a simple 8 or so character display assembled in a no frills 3d printed case that accepts data from current software and then formally sit yourself down to think about the next step. 

- I would approach your local government services and find a support group for the blind and demo your unit. Ask THEM what they want in a product as nobody else cares. There is also no way in heck your local government won't give you a small grant.

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