Modify an external pir sensor / gate alarm

Unsure if this question is best in alarms, automation or electrics Forum. I reckon this one...

We wanted a wireless garden gate chime, although couldn't find any waterproof wireless ones.
Amazon had a sale and got a PIR wireless waterproof jobby for £12 instead of £30.


It's too sensitive. If I move it next to the gate the bushes set it off. Up the garden path and the foxes set it off. Mostly at night. Spent a few weeks playing with locations and settings but it's useless due to false alarms.

Irritating.

Thought occurs that a PIR is just a NC (normally closed) switch, with drain. I have a NC reed switch (a spare door open sensor) for the house alarm.

If I de-solder the pir and replace with the reed switch, it would be in the waterproof case, and, if I attach the magnet to the gate I have a waterproof, wireless gate chime that'll only go off when the gate is opened.

Sounds genius.

Can anyone spot a problem with my plan, or, understanding of how these things work?

jacko555 said:

Unsure if this question is best in alarms, automation or electrics Forum. I reckon this one...

We wanted a wireless garden gate chime, although couldn't find any waterproof wireless ones.
Amazon had a sale and got a PIR wireless waterproof jobby for £12 instead of £30.
View attachment 236054

It's too sensitive. If I move it next to the gate the bushes set it off. Up the garden path and the foxes set it off. Mostly at night. Spent a few weeks playing with locations and settings but it's useless due to false alarms.

Irritating.

Thought occurs that a PIR is just a NC (normally closed) switch, with drain. I have a NC reed switch (a spare door open sensor) for the house alarm.

If I de-solder the pir and replace with the reed switch, it would be in the waterproof case, and, if I attach the magnet to the gate I have a waterproof, wireless gate chime that'll only go off when the gate is opened.

Sounds genius.

Can anyone spot a problem with my plan, or, understanding of how these things work?

Click to expand...

It all depends what your component level printed circuid board skills and reverse engineering capabilities.

Buy cheap …buy twice …

SUNRAY said:

It all depends what your component level printed circuid board skills and reverse engineering capabilities.

Click to expand...

I'd rate them as fair

sparkymarka said:

Buy cheap …buy twice …

Click to expand...

I would have spent more on a wireless, waterproof gate chime...

Can you find one?

For £12 it was worth the punt

sparkymarka said:

Buy cheap …buy twice …

Click to expand...

Not if you send it back quick with the returns policy/

Yes, alarm probably better.

jacko555 said:

...
Thought occurs that a PIR is just a NC (normally closed) switch, with drain. I have a NC reed switch (a spare door open sensor) for the house alarm.

If I de-solder the pir and replace with the reed switch, it would be in the waterproof case, and, if I attach the magnet to the gate I have a waterproof, wireless gate chime that'll only go off when the gate is opened.

Sounds genius.

Can anyone spot a problem with my plan, or, understanding of how these things work?

Click to expand...

Only that the PIR is likely to be NO (and close to operate a light/alarm/whatever).
But if it is indeed NC, then it will work. Only niggle will be the physical alignment - and having sufficient adjustment (the hardest being the face to face seperation distance). Working with shutter/roller door magent/reeds (big, chunky things) removes most of this hassle as they operated reliably over a good distance. If a metal gate, perhaps space in a small block.
Me, I used a standard burried door pair with magnet element in a small block of wood, painted black as the gate - works flawlessly.

The standard reed switch with some petroleum jelly over contacts will likely last a few years, and at £2 cheap enough, an electronic bell, I say electronic as less current, inside some thing like a bird box again will last for years, biggest problem is spiders. As to converting old unit to work as simple bell maybe it will work.

We have abandoned the idea of PIR, we use wifi switches so we can turn of lights with phone, but they have also been causing problems. It is not the detecting when not required, it is timing out before we have got into the door which has caused the problem, as to door bell, getting people to push it, seems everyone simply knocks the door, then when it does go, I think it is some thing on the TV.

ericmark said:

with some petroleum jelly over contacts will likely last a few years, and at £2 cheap enough, an electronic bell, I say electronic as less current, inside some thing like a bird box again will last for years, biggest problem is spiders. As to converting old unit to work as simple bell maybe it will work.

Click to expand...

Problem is the distance from the gate to the house - I want it to ring in the house, not the garden, and not have cables.

Gonna cracked it open this weekend, and I if I need NO or NC reed switch, I'll get one.

£12 was a bargin. I couldn't get a bell for that