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Topic: Arduino Lightsaber (Read 176086 times) previous topic - next topic

Protonerd

There are still a few issues that I need to solve:

  • Powering. I currently use the DC-DC Adjustable Step-up Module to boost the voltage to 4.7V, but the buck seems to have quite significant power loss. I haven't measured it precisely yet, but its efficiency seems to be around 50% around the current/voltage that I use.

    I am thinking of using 2 x 10440 batteries that would give me 6.5-8V range, but in that case, there would be more than 50% loss in the MOSFET LED driver (or on the resistor if you are using just a resistor), so there's no benefit in that either. But, I also have a step-down buck that I need to test for efficiency, so that might make things better.

    Alternatively, the Kyberos Mk2 will be using Cree instead of Luxeon Rebel LEDs, and these suckers work on lower voltage. Perhaps I'll just try powering the LED drivers directly from a single 18650 battery.

I recall I once planned to use an adjustable 3A rated DC/DC to boost up voltage from 3.7V to 7.2V, but it just broke down and could not even deliver 1A... so I do not believe what ebay DC/DC spec say any more. Anyway, do you power your whole build with the DC/DC? I personally think it's enough to power the logic, the LEDs you can conveniently supply from the 3.7V battery. It's also close to their max Vth, so no power waste occurs.



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  • Voltage drop on the kill-switch varies significantly with the current (from 0V to 0.3V), what messes up the LED driver currents and the readings of the ADXL335. My kill switch currently disconnects the BAT- from the GND, allowing me to connect an external charger adapter, but it causes the voltage drop problem. I am thinking of either moving the kill-switch from BAT- to BAT+ (fixing the floating LED Driver GND issue, but loosing the possibility to use an external charger), and/or making an electronic kill switch that would have a voltage drop independent from the current.


The electronic kill key is an interesting idea, any clue as to how to do it? Apart from using a kill-switch, of course (which I did once on a blaster build for a kid, for them it's way easier to switch off than to grasp the idea of not loosing a kill-key :)   )


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  • Measuring Li-Ion State Of Charge (Battery Level) is a project of its own. There are quite a few whitepapers and doctor theses on the subject. Still working on a reliable implementation


There is an idea I've got from this link: http://www.gammon.com.au/forum/?id=11497
I implemented it into FX-SaberOS, of course it only works if you run your full board off the battery. If a DC/DC is in between, it will obviously not work. I did not put a lot of effort into it, but tried to connect one of the analog pins to the battery while the voltage is pushed up to 5V, but I could  not make any reliable reading so far. It's not very high on my agenda but it's nagging at me.


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  • Light Diffusion Foil is another thing I am working on. The plain wrapping foil does not give even distribution and is not good enough in the daylight, so I am experimenting with some modifications of the wrapping foil that should dramatically improve its efficiency.



Hehe, actually there is no competing with the sun :) But really, these RGB LED modules cannot compete with other illumination types like neopixels or LED strings, neither in homogenity nor in brightness. I personally think that with many saber builders put countless hours to try to improve the blade diffusion frankly I do not think it can be improved any more... but please prove me wrong.

jbkuma

The easiest and most reliable way to read the battery level is a voltage divider.  I've tried almost every other method I could find and this is the only one that actually works.

I use a 100k from ground and 470k from bat+.  You can mine my implementation from my versions of LSOS and FXSOS. https://github.com/jbkuma

jenga67

Hi guys!
Thank you very much for developing the thread and saber building!

I have done my first build on WT588d-u, and now converting to DFPlayer mini and having some issues, so I would really appreciate your advice.
 
The current issue, as I assume, is with powering the whole setup.
I use:
Arduino pro micro 5v/16mhz
2x CR123A 3.7v 1000mah
DFPlayer mini
MPU6050
Red high power LED

How do you think, would it work ok if I power it all with only one CR123A, using a DC-DC stepup to 6v for arduino, stepdown to 2.4v for the LED, stepup to 4.2v for DFPlayer mini and MPU6050 straight with 3.7v from CR123A?

Or should I keep on using 2 CR123A's?

I already consider ordering 3.3v arduino, but I'm afraid it will not reach me until Halloween...

Big thanks guys!

Protonerd

Hi guys!
Thank you very much for developing the thread and saber building!

I have done my first build on WT588d-u, and now converting to DFPlayer mini and having some issues, so I would really appreciate your advice.
 
The current issue, as I assume, is with powering the whole setup.
I use:
Arduino pro micro 5v/16mhz
2x CR123A 3.7v 1000mah
DFPlayer mini
MPU6050
Red high power LED

How do you think, would it work ok if I power it all with only one CR123A, using a DC-DC stepup to 6v for arduino, stepdown to 2.4v for the LED, stepup to 4.2v for DFPlayer mini and MPU6050 straight with 3.7v from CR123A?

Or should I keep on using 2 CR123A's?

I already consider ordering 3.3v arduino, but I'm afraid it will not reach me until Halloween...

Big thanks guys!
One Step-up DC/DC to 6V would suffice, or even 5V if you connect it directly to the 5V pin and not to VIN. I'm not sure about the Micro, but if it has an FTDI chip, that one has an in-built 3.3V LDO (3V3 pin on the Nano). BTW, the DFPlayer mini also has an in-built 3.3V LDO, but alas I'm not sure any more if the signal is available on the breakout. On my Prime and Stardust boards I use either the LDO of the FTDI or of the DFPlayer chipset to supply the MPU.

Alternatively you can power your whole setup from a single 3.7V batttery, I've tried and it works. For the LEDs, do not supply them with a DC/DC, have them hooked up to the battery with resistors.

jenga67

Thanks a lot, Protonerd!

On Pro micro 5v there is one RAW pin for 5-12v input and VCC pin for regulated 5v, and either one can be used as an output of ~4.8v.

I have tried feeding 5v to Arduino and DF from the same DC-DC, but seems like it screws DFPlayer, as it starts with maximum volume (which cannot be controlled) and freezes after the first MPU triggering.
So I assumed that it needs lower voltage, like recommended 4.2v.

But why you would not recommend using step down to 2.4v for LED?


marsthrax

I'm interested in trying to build a bluetooth-enabled system. Before going through this thread, this is what I was leaning towards using:

Bluefruit Feather NRF52: https://www.adafruit.com/product/3406
Sound/SD: https://www.adafruit.com/product/3436
Gyro/Accel: https://www.adafruit.com/product/3463
Neopixel Jewel for LED: https://www.adafruit.com/product/2226
Surface Transducer for speaker: https://www.adafruit.com/product/1785
18650 Battery: http://www.thecustomsabershop.com/Panasonic-Li-Ion-18650-37V-3400mAh-PCB-Protected-Rechargeable-Battery-P853.aspx

It doesn't look like anyone has really used any of those components. I was hoping to get some input on whether this setup actually made sense, or if there are better options. A few specific questions:
1) Does a surface transducer make sense? It seemed like an interesting idea, and I saw somebody ask about it, but never saw a follow-up. Is it better to just go with a tried-and-true speaker for a lightsaber?
2)  I think my main sticking point so far is choice of sound. I'd much prefer a non-SD card option, but would probably 100MB-1GB to allow sufficient space for a few different configurable fonts. I haven't seen any good options for that. I'm also curious whether anyone really notices issues in practice with sound playing one after another, rather than mixing (say, keeping the hum sound always going and mixing in clash/blaster/etc).

I'm more of a software guy, so any input on whether the above setup seems practical (or if there are other things I should look into instead) would be greatly appreciated!

JakeSoft

I'm interested in trying to build a bluetooth-enabled system. Before going through this thread, this is what I was leaning towards using:

Bluefruit Feather NRF52: https://www.adafruit.com/product/3406
Sound/SD: https://www.adafruit.com/product/3436
Gyro/Accel: https://www.adafruit.com/product/3463
Neopixel Jewel for LED: https://www.adafruit.com/product/2226
Surface Transducer for speaker: https://www.adafruit.com/product/1785
18650 Battery: http://www.thecustomsabershop.com/Panasonic-Li-Ion-18650-37V-3400mAh-PCB-Protected-Rechargeable-Battery-P853.aspx

It doesn't look like anyone has really used any of those components. I was hoping to get some input on whether this setup actually made sense, or if there are better options. A few specific questions:
1) Does a surface transducer make sense? It seemed like an interesting idea, and I saw somebody ask about it, but never saw a follow-up. Is it better to just go with a tried-and-true speaker for a lightsaber?
2)  I think my main sticking point so far is choice of sound. I'd much prefer a non-SD card option, but would probably 100MB-1GB to allow sufficient space for a few different configurable fonts. I haven't seen any good options for that. I'm also curious whether anyone really notices issues in practice with sound playing one after another, rather than mixing (say, keeping the hum sound always going and mixing in clash/blaster/etc).

I'm more of a software guy, so any input on whether the above setup seems practical (or if there are other things I should look into instead) would be greatly appreciated!

I don't know anything about the sound board you linked so I can't testify about its performance. I looked at it a little in the link you provided, but couldn't really tell how hard/easy it is to use on the software side since you have to actually download the library to see any example code.

The old standbys around these parts are DFPlayer Mini (Link) and WT588D (just look on Ebay, tons of sellers).

If you want to try this new board out then please be my guest. It looks good on paper as far as supported features, so I don't see any obvious reason why it wouldn't work. Let us all know how it goes. Good luck.

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