Hello all,

I'm making a current monitor for the mains power line.  I plan on using =
an electrical outlet as an enclosure (probably plastic).  Not that it =
matters, but in case anyone is interested, I'll be using a PIC16F876A w/ =
one of those nifty Allegro current sensors (so cool BTW) and a 3 digit =
7seg. LED scrapped from a PC case.

Anyway, I remember there was a discussion recently about transformerless =
power supplies on the piclist.  I have found several similar schematics =
on the net for this scheme. =20

Here's my question, is there any way to make it work without the Zener =
diode?  Not that it's hard, but I'm trying to make this thing using =
stuff I already have, and I don't have any Zener diodes (damn Canadian =
RadioShack is going to the dogs).  I know they're probably like $0.15 at =
digikey, but then there's the min. order fee $5.00 and then shipping =
$8.00 so a handfull of zeners would cost me almost $15.00.  I really =
don't have enough money right now to order more stuff to make it =
worthwhile.

So is there any other way of doing this, like maybe a resistor divider =
or some such thing, fed into a regulator?  I really don't need much =
current, just enough for the pic to wake up, take a sample and go back =
to bed (and then the LEDs), maybe less than 100mA?.  Do any of you gurus =
know any good tricks on the cheap that'll do this?  Or should I just =
hack up a Wall Wart and use that transformer (might fight into the =
outlet box)?

Another quickie, can I use a little 600:600 audio transformer from a =
telephone to provide some isolation with the "transformerless" power =
supply?

In the meantime, I'll be routing through some scrap circuit boards from =
telephones and VCRs to see if I can find a suitable Zener diode.

Thanks ahead of time.

MJ Brush

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