>
>The power loss in the zener is the zener voltage times whatever the
>circuit draws. If the circuit draws nothing, the zener wastes nothing.
>The only thing more efficient would be an actual power converter (ie
>switching regulator).

However, there is NO regulation at all.
Any voltage variation on the supply is passed direct to the micro.

For that matter, if efficiency and low cost are the issue, why are we talking about a 9V battery?  Four AA cells and a series diode would give better regulation than the 9V/Zener system, and reverse protection as well. An LDO would be better, but I could argue for this system in a product design, in some cases.

Caps are needed in all cases, I figured those as a "gimme".


>>
>> As far as getting a newbie into trouble, I assume that the kit comes
>>...
>
>Just make sure newbies understand that a zener is supposed to be
>pointing the "wrong" way ;-)

It's not the zener that I'm worried about, it's the main supply.

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