Subject: From: Date:

Re: [ECS] Telephone Deadman switch Ingo Pakleppa Thu, 27 Aug 1998 11:29:15 -0400

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How about putting a 10V zener diode in series with a large resistor (large
so you don't drain too much current, but small enough for the zener diode to
work well)? Then just use the 10 as the input for the voltage regulator.
Or,. use a 5V zener diode and use the voltage across the zener diode
directly as input for your digital input. It's been a couple years since I
did this kind of stuff, so I don't remember what good dimensions would be.

Ingo Pakleppa (not Ingo Dean!)

Dan Carrington wrote:

> I have looked in my big book of electronic parts and it seems that
> voltage regulators allow input voltages up to about 35 volts.  If the
> phone system runs at 48 vdc and rings at 90 vac, any ideas as to how to
> limit the voltage that ends up at the regulator so as to not blow the
> thing?
>
> Dan Carrington
>
> Daniel Dubay wrote:
> >
> > I bet it would work.  Let us know.
> >
> > Dan Dubay
> >
> > >>> Dan Carrington <dc_grafx@microworks.net> 08/26 3:16 PM >>>
> > How about a regulator that puts out 5 volts that I could then directly
> > sense with a digital input with basically no current draw?
> >
> > Dan

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