Re: PIRs

["Dan Khan \(Work\)" <dhk@xxxxxxx>]

Thanks for the help.

Just need to save up for my homevision next...

-Dan

----- Original Message -----
From: "Steve Morgan" <steve@xxxxxxx>
To: <ukha_d@xxxxxxx>
Sent: Wednesday, January 16, 2002 5:20 PM
Subject: RE: [ukha_d] PIRs


> Dan,
>
> The PIR does not send a 'signal', as such - that's what they mean by
voltage
> free. It has a pair of contacts that are normally closed, completing a
> circuit. When the PIR triggers, the contacts open, breaking the
circuit.
It
> therefore acts like a switch that switches OFF when the PIR triggers.
>
> The 24V DC/50mA is the maximum rating of the contacts. i.e. don't
supply a
> voltage of more than 24V and don't use it in a circuit that draws more
than
> 50mA.
>
> You can use this with a powerflash module, but note that the effects
are
> reversed - in Mode 3, the powerflash would send OFF when the PIR
triggers
> and ON when it resets.
>
> Hope that helps,
> Steve
>
>
>
> > -----Original Message-----
> > From: mail.inovem.com [mailto:dhk@xxxxxxx]
> > Sent: 16 January 2002 15:46
> > To: UKHA_D
> > Subject: [ukha_d] PIRs
> >
> >
> > Just a quickie,
> >
> > I am about to purchase some PIRs and an X10 powerflash module
> > (for testing).
> >
> > The PIR spec states:
> >
> > a.. Alarm output: Normally closed voltage free relay
> > contacts, rated at
> > 24VDC, 50mA protected by 18-ohm series resistor
> >
> > What signal is sent when the PIR is triggered?  24V?  What
> > does the voltage
> > free bit mean? Does it mean that the actual contact that is
> > wired into on
> > the PIR are voltage free (thus you don't fry yourself when
> > connecting it
> > up?).  Is 24VDC too much for a powerflash?
> >
> > Little bit confused...
> >
> > -Dan
> >
> >
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