outside alarm system

[oldspark]

Hi Looked at a house today to do some electrics in. house out in the country, you drive over a small bridge thats approx 40 mtrs from the front door.
Bloke would like some form of senser at the bridge that provides an audio alarm in the house when a vehicle drives in.

Anyone point me in the direction of something like this.

Cheers
Os

 

[breezer]

external Active infra red beam

toy version clicky

 

[bernardgreen]

http://www.geoquip.com/pdf/rvdatasheets/m20active.pdf

Also available from RS Components Stock No. 331 613

 

[breezer]

good old Radio visor beams.

the "thing" is they are not that waterproof, but nothing a good squirt of silicone wont fix, you also need something to run them, i would suggest a cheap alarm panel, as it will supply the 12v to run them, wire it to a cct and put the cct on chime.

DON'T wire it to his existing alarm, becuse it will cause false alarms.

They are good but expensive, and dont forget you do need a pair, transmitter and receiver.

truth is these were not designed for outside use, as they have no heater to stop condensation, but a 100 ohm 5w resistor connected across the 12v works well

silicone on the top does work, pity i only had white

 

[bernardgreen]

The ones I have ( from RS ) certainly are water proof provided the cable gland is properly fitted and the correct mounting holes are used to fix it to the wall.

They do have a built in heater ( very simple 7 watt resistor ).

RS Components Stock No 331 613 provides the Tx and Rx pair.

My TX is partly obscured by thin vegetation but the system still detects people walking through the beam.

 

[breezer]

so are mine, but i have to date, lost one receiver in a bad storm, hence the silicone

 

[pdenni]

hi

check out gardiner security

optex beam sets are damn good, also you will need cheap alarm panel to run it,
perhaps another option whatabout an opal system? usually used for switching lights but could be tinkered with to just be used for the pir to give audible alert.

 

[breezer]

opal are PIRS, too much grief, it will pick up birds, animals etc, may not pick up a car, set of AIR beams will work no worries

 

[pdenni]

either product will pick up animals, just depends which one you prefer to install.

 

[breezer]

no it wont.

a set of beams should be mounted off the ground, their by a small animal can walk under it.

a pir looks down so no matter how high it is it will see an animal on the ground.

and if you really want to do it right, you should have 2 pairs of AIR beams at least 18 inches apart, mounted at opposite ends to each other so birds cant set it off.

i.e

TX.....................................RX



RX.....................................TX

This way one TX can not hold off both RX, and then if using RV beams you should sync them together

 

[pdenni]

not entirely true breezer as you could install a curtain pir which only looks the same angle as a beam, various possibilities on this one.
irrelevent of mounting at certain heights you will always run the risk with either option of activations due to animals.
I know this from installing both options over the years

 

[breezer]

I know this from installing both options over the years

well in that case then you will (or should) also know that a curtain pir can see "wider" the further you get away from it.

also a curtain pir as its name suggests "sees" a vertical whole area.(assuming its the right way up)


These two facts make a curtain pir of no use what so ever for this application, since they can still be triggered by animals. i.e. it will false alarm, still suseptabe to wind.

a set of AIR beams is the right bit of kit for this job. since the receiver is looking directly at the transmitter and wind itself can not set it off, neither can rain or fog.

Yes, the beam of the transmitter is conical (you did know that?) but since the receiver is looking at the centre of the cone (the brightest part) it is not suseptable to false aalrms as much as a pir is.

lets also not mention the fact of a hot day and a hot car

 

[oldspark]

Still thinking about this one..........

 

[breezer]

well its your choice but you do need a set of beams.
the radio visor ones are very good but other brands are available.

next time you see an electic gate sliding across the drive, go and have a look about 1/3rd the way up, you will find a set of beams