Re: [MH-list] FW: 12v PIR detectors ???


All (as far as I know) of the Burglar alarm type PIRs are 12V operation as all house alarms run on a 12V battery. The mains supply just keeps them charged up.
Any electrical wholesaler should be able to sell them to you for about 10 quid a go.
You might even be able to buy them from B&Q etc but avoid the cordless type. These have no connections so are useless for wiring in :)

The contacts in an alarm type PIR probably don't have a very high switching current and they probaly won't like switching mains voltages either, but as you are wanting one for the van then switching mains voltages probably isn't an issue.
The switching current on the ones that I use is only 50mA (0.05A), though some have a switch rating of 1A or more. Remember that 1 Amp is only 12 watts at 12 Volts.
It all depends if the alarm circuit is relay or solid state switching. Have a look around.

The other problem with alarm type PIRs is that the contacts are normally closed. This means that they open when they detect movement. A few do have a normally open contact as well (the switch closes as movement is detected), but it's not the norm.

All of the above problems can be overcome by using the PIR to switch a relay. This relay could then switch the lights on.

There are lights available for mounting on the outside of the van that have a PIR built in. These lights aren't cheap but they would do the job. These are of course powered by 12V.

There is a place that sell just what you need but sit yourself down before reading the prices :)
This place is :-

Have a good search around the net, and see if you have a local alarm wholesaler nearby.


KaraPaul wrote:

I have been thinking about this for a while ....
I wish to fit a couple of PIR detectors in/on my motorhome (both for
security and also for night-time approach/entry. There are numerous 220v on
sale for houses but surely the internals run on very few volts? - so 12v
should not be a problem?
Has anyone ever seen 12v PIRs for sale?

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