At 09:19 AM 9/16/2003 -0500, michael brown wrote:

>With all this talk about the CMX chips, I've been looking their line-up
>over.  I was thinking that I could use a PIC, a CMX602B and an LCD
>display without battery power to show who's calling yet never change
>batteries.  Does anyone have any idea how much power you could tap from
>the line without causing it to go off hook?  I know the number would
>probably be small, but I have yet another idea if that won't work.  ;-)

very little.

this page will help you a lot.
http://www.ce-mag.com/99ARG/Gubish233.html

>I know the DC loop is limited to small amount of maximum current, but
>the ringing signal seems to have quite some oomph behind it.  I'm
>wondering how hard it would be to capture the first ring to charge up
>some capacitors, and then use that to power up the PIC, LCD and CID
>chip, capture the data and then display it till the caps run down.
>Would it work?

current drawn during ring is how the co tells that you're off hook.

have a look at the link above, it will answer many questions.

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