Hi,

I've got a couple of covert CCTV PIRs in the house, and was wondering if normal PIRs for alarms are immune to these or not? If they are not, are there any that are? I thought DT PIRs are as they detect both heat and movement? Thanks

Kuchars22

Edited December 3, 200718 yr by kuchars22

i am also interested in the reply this question. because i thought the ir on cctv was light and the ir in the passive was infra radiated heat (body heat) there fore two different energies.. if my thinking is true, then the answer to your question, i think is yes (they should not detect them)....but hey i have being corrected in the past...

'Passive' infra red as in PIR merely detects a source of infra red detectable energy so one type of PIR is not going to cause a problem with another type of PIR as they both detect rather than emit.

IR LED's are an active source of infra red energy but because the PIR uses its lens to detect movement it should not be affected by the IR LED's as they will not provide a source of moving detectable infra red energy.

Edited December 3, 200718 yr by topalarms

except for when they switch on at dusk and throw infra red all over the place - you`ll just have to try them and see if they do

Sorry, the covert pir is only a dummy pir, so it only has a pinhole camera in it. I think the LED radiates at around 850nm, so the IR is visible at night.

that has got to be one of the funniest questions i have ever seen asked in here, i'm just rocking with laughter at the thought.

to be serious and apologising to the o/p, please don't worry, the led will have absolutely no effect.

technical reason -: apart from the pir 'looking' for movement from a radiated heat source in the range of 3 degs a second you will understand it has to be far greater than what can be emitted by any cheap LED, or camera. fortunat coincidence really, or pirs and camera's would need to be housed in heat proof housings or they would melt .

the pir also 'looks' down, so away from your LED 'heat' source, so unless you mounted the camera in the skirting board looking up (if so - whats the web site please? ) you will be just fine.

regs

alan

Edited December 3, 200718 yr by arfur mo

that has got to be one of the funniest questions i have ever seen asked in here, i'm just rocking with laughter at the thought.

to be serious and apologising to the o/p, please don't worry, the led will have absolutely no effect.

technical reason -: apart from the pir 'looking' for movement from a radiated heat source in the range of 3 degs a second you will understand it has to be far greater than what can be emitted by any cheap LED, or camera. fortunat coincidence really, or pirs and camera's would need to be housed in heat proof housings or they would melt .

the pir also 'looks' down, so away from your LED 'heat' source, so unless you mounted the camera in the skirting board looking up (if so - whats the web site please? ) you will be just fine.

regs

alan

You are right very funny question but a think a valid one especially in the d.i.y area

I would still like to try it to prove it

You are right very funny question but a think a valid one especially in the d.i.y area

maybe,

attending a call on a system false alarming on a pir (in days before self employment ), a previous engineer (known as a bit of a numb nuts) had blamed the fish in a fish tank, so with as straight a face as i could muster as i had to protect the firm, i said "he was 'understandably' mistaken as although they are tropical fish - they are cold blooded, and pir's worked on movement of heat" (will i ever get to heaven?).

best of it was there were only 2 tiny neons - in an 8 ft tank .

apparently they had a problem with the tank heater a few weeks prior which had killed all but these two fish, while getting the docket signed i was asked as the fish lost were very expensive "could 'we' alarm the tank" - i nearly cracked up, i had to go outside to 'compose' myself for ten minutes.

regs

alan

that has got to be one of the funniest questions i have ever seen asked in here, i'm just rocking with laughter at the thought.

to be serious and apologising to the o/p, please don't worry, the led will have absolutely no effect.

technical reason -: apart from the pir 'looking' for movement from a radiated heat source in the range of 3 degs a second you will understand it has to be far greater than what can be emitted by any cheap LED, or camera. fortunat coincidence really, or pirs and camera's would need to be housed in heat proof housings or they would melt .

the pir also 'looks' down, so away from your LED 'heat' source, so unless you mounted the camera in the skirting board looking up (if so - whats the web site please? ) you will be just fine.

regs

alan

Yeah, but you got to remember that I'm not in the trade. I know that IRs in cameras can generate enough heat to satisfiy a spider's ar5e, and a convector heater can affect the PIR (as mentioned in the Hints and Tips of installing an alarm system). Put heat and heat movement as in a convector heater together, and I assumed that I asked a straightforward question. Not being technical in PIRs, I don't know what level of heat is enough to set off a PIR. What if it was a powerful dennard lamp sitting on a PTZ? Is this still not enough to trigger the PIR (have you fallen of your seat yet?!)

But now that I know, I still can't see the funny side?!