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Old Jun 06, 2009, 04:28 AM
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Magicsmoke maker
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Australia, QLD, Charters Towers
Joined Dec 2003
17,426 Posts
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.

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