PIR Activation!

Hi,

I'm new to the forum, with a relatively simple question that perhaps someone can help.

I have a wide electrical engineering background and experience, but limited intruder/fire alarm experience. Put one or two in over the years for me and friends. 

I have installed a pretty simple intruder detector outside the back of my house - separate PIR activating wireless to a LED flood and internal buzzer. I realise a PIR  basically operates by detecting IR passing past the segments of the lens, and that everything has some IR e.g. background,  and thats why detection is identified while passing past the segment, as opposed to remaining balanced in the segments.

However my pesky PIR operates when some of the the washing is drying on the clothes line! It that it you think, IR flapping across the segments, which is enough to operate it?

Any comments appreciated.

You are not wrong.

Also you could look at it this way. The fact that when the washing is blown by the wind the PIR activates, but yet the PIR does not activate when the washing does not move indicates it is the washing / wind combination that is causing the activations.

Then there is the fact that some "long range" PIR sensors can easily "see" 50M away, so of they can see that*, washing close up, no problem.

*It is also to do with the lens or mirror configuration as to how far  /  wide a PIR sensor can see.

Thanks Richard,

I'll just hope I get no intruders when the washing is out! I enclosed the PIR in  a fake bird-box (to fool the unsuspecting intruder). I'm getting paranoid now - I'm wondering if a spider made a web in front of the lens, and scurried across - I may be in further trouble! Oh well, complete out one job and create another I guess!

Mal

Wildlife , like hedgehogs, foxes , badgers,and domestic pets can add to your problems too.

 Pir's are far from foolproof. Radio waves have their problems too, taxi's police radio's etc can also have an effect on them.

Ruston,

Thanks for the infor. But apart from all these issues......... they are ok - perharps! (I was almost in the Romans sketch from the Monty Python film)

Looking at your photo - perhaps some quarrying background!

Mal

Yes . Opencast mining. Many years ago now though.

Brought up around heavy earth moving equipment.

Opencast mining!

I remember those days - when there used to be real industry in the UK!

I used to do the statutory electrical testing on opencast and quarries in S Wales, including the excavators. There was an old American Dragline down here - working on 60 cycles. The site had a frequency converter plant from 60 to 50 cycles onto overhead lines to the machine. At the end of its life British Coal sold it for spares back to the Americans.

Was it a Marion or Bucyrus Erie?

 We had the largest draglines in Europe up here , the most famous being 'Big Geoerdie.' he was a BE 1550 . weighed in at 300 tons. he was the smallest of his three successors.

 When his working life was over they tried to sell him on , the deal fell through and he was cut up for scrap.

 There are two small sites left , soon to close . Maybe an even smaller one in the pipeline, but is under severe opposition.

To my knowledge there are no electric machines working on the current sites.

PS. Tony and Rob are ex quarry men too.

I wouldn't "disguise" the PIR, 3 reasons

1) Waste of time

2) Potential burglar will not be looking for one / doesn't care if there is one.

3) Can have an effect on the PIR depending on enclosure.

a) If its too narrow it can reduce the "angle of view" of the PIR

b) If its too wide it will become a home for spiders to make a web and walk in-front of the PIR

c) Believe it or not you can get "air currents" in the enclosure activating the PIR 

ruston said:

PS. Tony and Rob are ex quarry men too.

Click to expand...

Only for a year before I found somewhere warm to build my nest. Kilns and furnaces becoming my home for the next forty years. Very occasionally I’d be dragged kicking and screaming in to the quarry for an emergency.

I don’t like being cold!

Ruston’s avatar is the last RB I worked on before it was cut up for scrap.

With the exception of the paint job, it actually looks in good condition.

 That would be an old navvy even when you were there.

It was the last of the RB’s bought in the 50’s. The other five had been repainted and renumbered by the time I started.

They were numbered RSxxx, Road Service vehicle as were the dumpers, front end loaders and rail loco’s.

Yes love I’m just off to the shops for you I’ll take RS9 it’s easier to park.

Hunslet 040 .

I had to google that , but I  envy you if you drove one of those.

Silly job of the day.

“Can you find out if the brakes will release on that heap of junk because we’ve flogged it to a rail preservation society.”

“OK, sounds fun.”

With the fitters in tow I released the hand brake while they watched either side of the loco. The brakes released OK, I couldn’t get them back on! The iron carriage coupled to the loco came along for the ride.




It was embarrassing when we were towed back to the stabling yard, everyone on the plant knew about it and there was a reception party waiting.

The loco is now fully restored and working on the Rutland railway

That's the sort of thing you never live down , and the story gets bigger with the years.

Unlike the plant, all totally flattened  :Salute

Same here , green fields and a golf course. 

The other one , green fields , lake and country park, and a nature reserve.

They’re trying to flog land poisoned by arsenic and cyanide as prime building land.

Anyone fancy growing your own vegetables in the garden? Good home grown food for all the family.