i'm just not a fan of using regulators unless absolutely necessary. linear regulators have to have huge heat sinks to handle the current needed for a bunch of big servos and just waste the dropped voltage as heat. an efficient switching regulator that can handle the current also gets so big and heavy that you may as well go back to a regular 5 cell pack...also costs big bucks...

for flight packs i and some others have been using 2 cell li-pos without regulators. in reality they put out less than a volt more than a fresh 5 cell pack and most servos take it just fine. those that don't seem to like it just get a diode added to the positive lead to drop the voltage a bit. receivers have no problems as they're regulated internally.

but since we're talking ignitions it gets a lot more doable due to much lower current and the fact that a failure just means landing dead-stick...and we all know how to do that

google "LM7805" and you'll get a bunch of data sheets with schematics for their proper use. normally just two caps are needed and their specs aren't to important. but a much better choice IMO would be an LM2940 low-dropout regulator that only needs an input of 0.5 volts higher than the output, about $1.50 at digikey. same exact schematic as the 7805 but here it is very important that the cap on the output meets the specs in the data sheet. searching digikey i find that all the leaded caps that fit are $$$ but part #478-1759-1-ND for $1.20 would do nicely. this is a tiny SMT chip that could be soldered right across two leads of the regulator.

another choice might be a switcher like this: http://www.dimensionengineering.com/DE-SW0XX.htm ready to use, good price and the voltage dropped isn't just wasted as heat but turned into added capacity. and best of all is that they don't rape you with their shipping costs.


dave