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Old Jun 06, 2009, 04:28 AM
PLD
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Extreme Edition of the BAC-004

This is really more of a post-incubator device. I took the standard BAC-004, which is a very nice device already and tried to see what I could 'upgrade' on it.

The new one is the BAC-004 'EE' (or just PLD-BAC-EE), If you take the now standard BAC-004 and make the following changes;

* Quadruple the size of the low-ESR 5V side cap
* Add a 52'C/W heatsink to the regulator (the bare DPAK device alone is 100'C/W
* Add a brown-out/low-voltage detector (eg, below 4.3V)
* Switch to 22AWG wiring

The aim of this version is to give a larger margin of operation compared to the standard BAC-004 unit. The heatsink gives us another 1W dissipation capacity typically over the normal non-heatsink version. The larger low-ESR cap means we can cope with larger 'instant demands' from servos, as well as squelching more ripples.

Now the really new feature here is the brown-out/low-voltage warning. If while you are flying something happens (eg, a servo bind or such) and it pulls the power down below 4.3V for more than a mS or so, it'll register on the BAC unit. The BAC will then blink the "error" LED for each time a brownout has occured (up to about 5 times, then it just stays at 5, no point making it indicate more, since clearly there's an "issue" if you get more than 1 or 2). If there's a brownout detected, it'll also continuously 'pip' the speaker (I might change this) ever couple of seconds to let you know "Oi! something went wrong".

Theoretically we shouldn't see the brownout light trigger but consider it as a "You should check your setup" type light.

Right now I've not got it ready for the store, I'm still running more tests to see what sort of loads are needed to drive it to the brownout situation.


Paul.
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Old Jun 11, 2009, 12:57 AM
PLD
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Okay, around and around we go... so here's another idea to throw some fun in the mix

What about a lipo charger/balancer for small packs, eg, up to 250mAh.

All the bigger ones do 100mA charge steps which tends to be a bit coarse for for smaller packs (and disasterous potentially for 50mA packs etc).

Paul.
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Old Jun 11, 2009, 05:27 AM
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Quote:
Originally Posted by pldaniels
Okay, around and around we go... so here's another idea to throw some fun in the mix

What about a lipo charger/balancer for small packs, eg, up to 250mAh.

All the bigger ones do 100mA charge steps which tends to be a bit coarse for for smaller packs (and disasterous potentially for 50mA packs etc).

Paul.
My charger/balancer goes down to 100ma and I've used it on 50mah and 70mah cells a bunch with no issues. Generally, the smaller cells can tolerate a bit over 1C with no problems.

Unless you are going to really, really small cells like 10mah, then I think 100mah steps is fine. You'll always be within 50ma of 1C.
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Old Aug 07, 2009, 09:48 PM
Bradster
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I would like to see module to convert hobby irons from very inaccurate bi metal temperature control to using electronic control, similar to that used on soldering irons.
I get frustrated with my iron because the temp can vary by huge amounts
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Old Aug 07, 2009, 09:51 PM
Bush Mechanic
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Not a bad idea that one
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Old Aug 07, 2009, 09:59 PM
PLD
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Are you referring to the actual covering irons?
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Old Aug 08, 2009, 06:17 AM
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Just get a better iron

http://www.coverite.com/accys/covr2700.html
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Old Aug 08, 2009, 04:11 PM
Bush Mechanic
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Quote:
Originally Posted by pldaniels
Are you referring to the actual covering irons?
Yes Paul.
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Old Aug 19, 2009, 04:02 AM
Bradster
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Quote:
Originally Posted by pldaniels
Are you referring to the actual covering irons?
Yes, I am talking about the covering irons. Until I saw the link for the coverite iron, I have never seen an iron that uses electronic control.
What I had envisioned was a very simple feedback circuit to control the on/off part rather than the bi-metal strip which has a very large hysteresis.
I suppose the fact that you would be switching 240 VAC may make it more difficult at least from the safety point of view.
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Old Aug 19, 2009, 04:59 AM
PLD
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Yes, alas getting a safe mod for such a thing would be rather difficult. There's a few 240V related projects I'd love to bring to market but having them all certified is just absurdly costly

Paul.
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Old Aug 29, 2009, 10:24 PM
Bush Mechanic
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Crazy idea.

BAC for 2 batteries in parallel. When batt A drops below voltage batt B takes over. Without power down batt A cannot be reconnected. If batt A is low on powerup then batt B will be re connected anyway.

I was reading about people wanting to do the LSF 8 hour flights, this could be good for them. Idea being say 2 x 850mAh Lipo (or even 2 x 1000) takes less space (lengthwise) than a 1600mAh (or 2000mAh). Could be for 2S or 3S.

Crazy or not, you be the judge.

Neil.
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Old Aug 29, 2009, 10:29 PM
PLD
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Neil,

Actually a simple 2-schottky-diode configuration works fine for that. The packs will then automagically balance in their depletion concurrently, there won't be a "first A, then B" type large-scale switching. You can expand this out to as many packs as required.

The "downside" is that you lose 0.3V (roughly) in the diode, though if you're feeding into a linear regulator/BAC then it's actually useful as it means the BAC has to dissipate less heat. (at max, say 1A, it'll drop from 3.4W dissipation to 3.1W)

Paul.
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Old Aug 30, 2009, 05:57 AM
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http://www.fromeco.org/Products/04FR...b/Default.aspx
http://www.ramrcandramtrack.com/rcfails.html

and more if you care to search for them.
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Old Aug 30, 2009, 06:24 AM
Bush Mechanic
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I don't like mechanical switches, specially those rotten fall apart, when you don't want them to, slide switches. I was thinking all electronic perhaps with Pauls, charge plug as the de-activator..............an extension/expansion of the charge/BAC.
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Old Sep 11, 2009, 12:27 AM
PLD
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So... I wonder if I should make my little foam cutter into an actual product...
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