PIR repair

[Badger1oo]

Hi, The plastic lens on a PIR for an external light became brittle and crumbled into pieces. I did a neat repair using some plastic from a plastic squash bottle. It looks like new, but the sensor now barely detects motion unless it is within an inch of the sensor. Is there some other type of plastic which might do the job ?.

 

[doingitmeself]

Bin!

The plastic is actually a lens which focuses IR radiation from the room into carefully designed 'zones' on the IR receiver. Replacing it with a piece of ordinary plastic isn't going to work I'm afraid.

These lights are so cheap that it's not worth the hassle. Bin it and buy another for a tenner.

 

[josh451]

WTF? A squash bottle.

That fookin hilarious!

Basil Fawlty would do something like that ahaha!

 

[SandyLyon]

No, the lens difusses the PIR into "Fingers" on 3 levels.

A piece of plastic will be next to useless.

If you can't get a replacement lens, then it's a new PIR / light I'm afraid

 

[joe-90]

It's a Fresnel lens named after the Fresnel bros originally used in light houses. (Pronounced Frennell).

 

[Europlex]

It's a Fresnel lens named after the Fresnel bros originally used in light houses. (Pronounced Frennell).

Is there anything you don't know Joe? I didn't know about the pronunciation.

Noticed how quiet it is now?

 

[joe-90]

Has he gone on holiday? Or didn't he take my warning of what happens to trouble makers seriously?

 

[Badger1oo]

No, the lens difusses the PIR into "Fingers" on 3 levels.

A piece of plastic will be next to useless.

If you can't get a replacement lens, then it's a new PIR / light I'm afraid

Ok thanks to every body for their help, even the p*sstaker, looks like a new one then.

 

[fpb]

I cut a piece to size from a plastic milk container. It works just as well and in exactly the same way as the original.

 

[sparkymarka]

And ?

 

[secureiam]

I almost wet myself, some PIR's may lend them selves to some sort of detection with such repairs, however lenses are designed to provide certain coverage patterns with certain detectors, so even the same manufacturer will have different lenses for different jobs on the same PIR, curtain lens for example is an option on some systems, which effectively narrows down the detection area it almost a beam (in simple terms).

The more sections to the lens the better in theory at least for the detector to differentiate between a real event and a false one, but its a little more complicated than that.

 

[bernardgreen]

and in exactly the same way as the original.

The questions to be asked are .......

How well did the original work ?

If the original worked why was it nescessary to replace it ?

 

[Europlex]

Bernard, you obviously didn't read the first line

Hi, The plastic lens on a PIR for an external light became brittle and crumbled into pieces. I did a neat repair using some plastic from a plastic squash bottle. It looks like new, but the sensor now barely detects motion unless it is within an inch of the sensor. Is there some other type of plastic which might do the job ?.

WTF? A squash bottle.

That fookin hilarious!
Basil Fawlty would do something like that ahaha!

Bernard, the broken lens is why it has to be replaced. Not going to find a new lens anywhere.

 

[bernardgreen]

My reply was to fp's post which came out of the blue more than 5 years after the original post from Badger1oo

I cut a piece to size from a plastic milk container. It works just as well and in exactly the same way as the original.

 

[fpb]

And ?

What do you mean: "And ?"