Schematic approval

[hedgehog1]

Thanks HH,

I did consider this type of setup but discounted it for the following reasons (please let me know if you think reasonable):
1) reduced run time by using 7.4V
2) I have a complete LiPo setup already - charger, leads etc... (excluding the battery I would need for this project)
3) If using LiPo a requirement, then no way to (easily) split output from one cell.

Any idea whether using a MOSFET would allow ramp up/down effects?

BW,
Mike

If you use Pulse Width Modification (a.k.a Duty Cycles), either MOPSFETs or the PEX will work since you are really only doing 100% on, 100% off very rapidly.

While I have not checked the output of an NB on a scope, because it has no current driver on board I am assuming it uses Pulse Width Modification to achieve what 'appear' to be dimming effects including power up/down and blade flicker. Erv could answer that for sure.

As to Ari-Jaq Xulden's point: I know you can get this level of power from Li-Ions and cram them into a hilt. I don't know myself if the LiPO packs can give you 2 amps continuous output.

[hedgehog1]

I would do this a little bit differently. Tri-Rebel Greens tend to have a lower vF per die than the LedEngins. I would go Tri-Green with a single 18650 3.7v, using power extenders to allow each die to be driven at 700mA to 1A. Less batteries, less parts, easier to do.

You could also go with two 18650 3.7v in parallel to get about the same run time as two 18650 in series. I like this idea, PR!

[mikeclem]

Hi,

The current output is dependent on what the application draws from it but the LiPo I have in mind can potentially deliver up to 16.5 Amps (15C @ 1100mAh).

The dimension are 100mm x 18mm x 20mm (so long and thin) - it'll fit nicely although I haven't got round to working out exactly how to stop it rattling around inside (I have previously wrapped in foam to increase the diameter in another project).

I'm not sure what you mean by: "Nor do their outputs match that of a comparable cell size, even burning through the current at twice the rate.'
I think what you're saying is the capacity (in mAh) is not as high and I concede that point with the example I have used that but at cell dimensions of 18mm X 65mm it is a much larger pack for a similar energy output - even burning the current at twice the rate. If I've misunderstood please do clarify.

I think generally folks are a little cautious of LiPo's - which is understandable as one of the first things you'll see if you search on You Tube is a series of rather dramatic explosions. However, it is now a proven technology in the RC community for a few years now. Most folks I know who fly have binned their I/C engines in favour of LiPo/Brushless motors due to the energy density/power curve of this combination. However, I acknowledge the fact that this is not that kind of application it is being applied to here.

It is just a battery and as long as it charged appropriately, not hit with a hammer, punctured, immersed in water or short circuited it will behave itself. Anyway, I didn't want this to turn in to a 'here comes another madman wanting to use LiPo's thread'. If it's easier, assume I'll use 4 X 17650's in series - they would provide the same output (but you'll have to imagine that they fit in the hilt).

Given this, the question I am asking (given that I am confident around the power source) is: will the schematic work in principle and if using a Power Xtender / MOSFET will ramp up/down effects be maintained with an NB?

BW,
Mike

[mikeclem]

Sorry, bit of cross posting going on - my response above was to Ari-Jaq Xulden.

Thanks PR and HH. I'm looking to go BRIGHT! When I last made a saber all that was around were 3W LED's - and while adequate I was never wholly satisfied - it matched my MR but didn't exceed it. Things have moved on and now I want something that will sear retinas while also being visible from space. That is what I am chasing.

PR states less batteries but if I use a LiPo it is only 1 battery - but I appreciate the challenges in down regulating the current for the LED and voltage for the NB. If it was easy then everyone would be doing it!

Thanks for the info regarding the duty cycles of the board. I suspect you are right, but as you say, would be nice to have it confirmed.

Mike

[hedgehog1]

Hi,
... Given this, the question I am asking (given that I am confident around the power source) is: will the schematic work in principle and if using a Power Xtender / MOSFET will ramp up/down effects be maintained with an NB?

BW,
Mike

I believe the NBs Ramp Up/Down and Blade Flicker effects will be maintained using a Power Xtender / MOSFET.

[hedgehog1]

Great - now you have peaked my curiosity. Might I ask for the part number or link to the LiPo you plan on using? I want to get to know them better....

[mikeclem]

Here you go, mount 1 on top of each other:
http://shop.ehobbyasia.com/king-arms...m-battery.html

There is also a 1400mAh version but it is slightly longer and twice the price (and I rather just buy 2 of the 1100's if it came to it). It does have a higher discharge capacity though - but as I say, for this application not really a consideration:
http://shop.ehobbyasia.com/systema-1...x-mad-max.html

I'm in the chat room if you want to discuss further.....

Ta,
Mike

[hedgehog1]

here is the link asking Erv if the NB uses PWM/Duty Cycling:

http://www.fx-sabers.com/forum/index.php?topic=39811.0

[Silver Serpent]

Hedgehog, I just wanted to say that your earlier wiring diagrams are a most imaginative solution to running a LEDEngin with the NB. Splitting the battery pack is not the sort of thing I would have ever considered.

I'm still trying to wrap my head around how to hook in a recharge port. Maybe after a good night's rest...

[hedgehog1]

SS,

Thanks for the positive words.

As to recharging LiPos, it appears that every cell is recharged seperately using the secondary wiring on the packs. If this is the case, then a two conductor recharge port will not work. The packs will have to use two wires for every cell in the LiPo pack; so that means removing the pack for recharging or using much larger recharge connector and a real on/off switch.

EDIT: The LiPOs packs are charged in parallel after all: please disregard the italicized text above.