Chuck Harkness wrote:

>I think that's what confused me most. The diagram said 12V secondary on
>transformer and 9.1+5 = 14V.  Why didn't they just use a higher voltage
>regulator instead of the zener + 5V?  I promise no more questions about this
>after this one.
>
>Chuck H.
>
>
There are many reasons to do so, but they all usually depend on
circumstances and needs.
One reason might be that they needed a specific output (14.1) with a
certian accuracy (say 5%) but they only had 10% resistors on hand (which
is what a variable regulator uses to determine its output voltage). So
they might have decided to use the zener and regulator combination to
get accuracy.  (not too likely)

It could also be cheaper (not too likely, but possible)

It could be what they had in their junk box when they built it (quite
possible)

-Adam

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