Thats why you also add a regular diode and compensate with a lesser
value zener. I believe this was already mentioned. But in assembly, it
is easy for a newbie to be confused about how a zener works
differently than a regular diode.

Yes there is no regulation, but is it required? It depends on the
ciruit and I don't think that a blink-a-led needs regulation. PICs do
not always need regulation, especially with such a wide operating
voltage range of most PICs. I have found the INTRC to be very
forgiving of supply variation and have not had a PIC lock up due to
supply ripple.

9v is the de-facto standard power supply for newbies. What could be
easier for a newbie to diagnose and replace?

my $1/50

- Ben



On Thu, 1 Jul 2004 14:02:32 -0500, David VanHorn <dvanhorn@cedar.net> wrote:
>
> >
> >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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