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Old Nov 03, 2011, 11:19 AM
PLD
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PLD-BACALL: 1S lipo to 5V booster with charger, volts disp, LMA and switch

I've been in discussions with another vendor of R/C goods and it's been decided to give a "complete package" BAC a shot, using a 1S lipo as the power source, for simplicity and compactness.

The BACALL will do the following:
* Boost 1S to 5V @1A
* Allow properly managed charging on-board using a dedicated lipo charge chip
* Charge using USB power or other 5V source
* Voltage readout of 1S pack
* Low voltage alarm
* Integrated power switch
* Option for Magnetically activated power on/off
* Lost model alarm

It's an exotic little project that's been brewing for some time and that's a lot of features to pack into a tiny 22 x 38mm board (same size as small 280mAh lipo cells! There's a great deal of design expertise being pulled together here from a lot of other different projects I have done over the years. Sincerely hoping this will work well.

PCB boards have been already submitted for prototype production - 2~3 weeks before they arrive.
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Old Nov 03, 2011, 07:50 PM
KJ4WFG
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Hi Paul -- Interesting. I wish everybody provided such clear specs and design goals. What's the application that this is targeted for? The 1S to 5v sounds like I could run my Rx and servos with it using a nice light weight LiPo, but the 1amp leaves me uncertain what size airplane/equipment you're targeting (car, maybe?). What's the mental picture in there of the target market. You got lotsastuff goin on right now. Very cool. Subscribing. Best regards........... R
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Old Nov 03, 2011, 07:54 PM
PLD
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modbuilder,

Primary market is the DLG community. This is a bit of an extension of the current BAC/BEC units that I have done.

1A doesn't seem a lot, though consider that it would work for RX/servo power on any device currently using a "1A BEC equipped ESC" (which really only can deliver about 500mA and only on 2S).

So, ultimately you could simply say "gliders with up to 6 x 9g servos"

Tx for the subscribe, it's going to be a very busy month or two leading in to the new year

Paul.
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Old Nov 06, 2011, 05:43 AM
PLD
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PCBs have been shipped (just received notification from factory).

Seems quite a few different boards have shipped, what's strange is that some of the earlier ones haven't yet come through *scratches head*.

Anticipate ~2wks delivery.
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Old Nov 06, 2011, 08:18 AM
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Just a comment on the charging feature, 5 volts is a weird voltage to have laying around at the flying field don't you think? Or were you thinking we would have larger capacity receiver packs laying around that we would use??

Do you think input from a small 6v lead-acid battery would be within limits....or better yet a larger 2s lipo pack?? (I know, that's probably pushing it)

Just seeing about the options Thanks!
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Old Nov 06, 2011, 08:24 AM
PLD
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Quote:
Originally Posted by Nathan Schmoekel View Post
Just a comment on the charging feature, 5 volts is a weird voltage to have laying around at the flying field don't you think?
The plan is to run off a USB port, now those there's quite a few around - or just in the car there's plenty of 12V -> USB adapters. 6V is the -absolute max- voltage I can drive the chip at and I generally don't like pushing that far into the specs. There is a second option, but it's a more expensive chip, which would let me accept a 2S lipo (or up to 9V), but it is a lot more expensive and only lets me set the charge rate to 200mA max, as opposed to 300mA that I was planning for.

btw, thanks for popping in, and I'm more than happy to be asked such questions

Paul.
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Old Nov 06, 2011, 08:32 AM
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I had not thought of the USB-car power adapters. That's an easy enough solution.

I suppose one could hook up an old un-used ESC to a 2cell lipo and have just the right voltage output from the BEC's power too..... I thought of that about one second after I hit the submit button

As always, you do great work....I'm sure I'm not the only one happy to see you still in the game
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Old Nov 06, 2011, 08:35 AM
PLD
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It's a tough game to be in - though I'm not complaining about that, I do enjoy the rush of designing.

Hoping that this first set of boards work acceptably well (that is, they _work_ ), as is often the case when bringing together so many unique parts, while they individually might work, sometimes they don't work together.

The trickiest part of this is actually the soft-switch combined with the switchmode power-supply. I don't want any crazy things happening.

At least for now there's still some BAC55 / ESJ6-55 units to build, though I have to restock on a lot of things again soon (wires!)
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Old Nov 15, 2011, 04:46 AM
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What do you think about estimate sales price for this device?
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Old Nov 15, 2011, 05:09 AM
PLD
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Quote:
Originally Posted by Shread View Post
What do you think about estimate sales price for this device?
*pinky in the corner of the mouth* "1 billion dollars!"

The full package is certainly going to be more than the existing BAC units, no way to avoid that with all the extra parts like the onboard charger and of course the switch mode controller. I'm thumb-sucking that they'll be somewhere around the $45 AUD mark. Dropping the charge controller will reduce that a bit.

A lot depends on things like (a) will the board even work properly (if so, that's good!), and (b) what pricing can I get for the parts in 100~1000 lot units. There's several new parts on this board which I've not used in the past, so seeking out the optimal pricing has yet to be done.

The big BIG contention is the actual switch-mode controller. If it works well with the planned chip then the pricing should stay about where my thumbsuck is. On the other hand if it doesn't then I have to go to the more expensive option which also requires different coil/cap/diode combinations and thus throws things out again.

It's somewhat insanely hilarious that the switchmode controller chip, on its own, costs more than what you can buy an entire completed 3A Turnigy buck-coverter unit from HK.... and that's when I look at their reel pricing (1000~5000 units).
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Old Nov 15, 2011, 05:16 AM
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Do not try to compare your price with china made devices, China supplier typicaly sell device for the cost wich we will pay only for parts even on 10000pcs order))))
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Old Nov 15, 2011, 05:35 AM
PLD
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I agree... but it's still very frustrating,more so too that the chips are designed by US/EU companies (in this case, Linear, Microchip and Atmel ).
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Old Nov 15, 2011, 06:27 AM
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Very simple answer - they use components stolen from manufacturing fabs, you can buy the same components from china scrapyard if you do not care about your customers))) Lots of them availible via alibaba.com))
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Old Nov 15, 2011, 06:30 AM
PLD
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Ah yes... I've seen those a lot. I do get a lot of gear via Alibaba sources, wiring looms, LCD panels, connectors etc, but I use it more as a business contact point shopping site. I've seen those "shady" offers too "Oh wow, it's 1/4 the price I normally pay!!!", usually on AliExpress.

I think the worst thing I've had with business like that is when the samples are not the same as the things they send you.

I have 2000 buzzers here that are no good to me because they didn't live up to the 90dB output the samples gave me. Anyone want some KIA 4-pad square SMD buzzers?
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Old Nov 22, 2011, 12:27 AM
PLD
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Progress has been good on the BACALL, all facilities now are functioning as planned, now it's a matter of fine-tuning things to make sure that I've not missed something obvious (and that happens all too often).

Some pictures of the setup.
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