RE: PIRs

["Steve Morgan" <steve@xxxxxxx>]

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
>
>
> ------------------------ Yahoo! Groups Sponsor
> ---------------------~-->
> Tiny Wireless Camera under $80!
> Order Now! FREE VCR Commander!
> Click Here - Only 1 Day Left!
> http://us.click.yahoo.com/WoOlbB/7.PDAA/ySSFAA/IBOolB/TM
> --------------------------------------------------------------
> -------~->
>
> For more information: http://www.automatedhome.co.uk
> Post message: ukha_d@xxxxxxx
> Subscribe:  ukha_d-subscribe@xxxxxxx
> Unsubscribe:  ukha_d-unsubscribe@xxxxxxx
> List owner:  ukha_d-owner@xxxxxxx
>
> Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/