IR illuminators

[electronicsuk 0]

Hello guys. This is my first post here, so please bear with me!

 

Just this weekend I installed a CCTV camera for a relative who'd been having trouble with youths congregating outside his home. The camera itself is nothing special, just a small monochrome PIR unit from Wickes, chosen because the price was right and I've also got four similar colour PIR units around the house which do a pretty good job for what they cost.

 

Now, during the daytime the camera provides a perfectly acceptable picture, and I made the assumption that under normal streetlit conditions the camera would give acceptable night time performance, at least equal to or better than what I get on my colour units back at home. What I didn't notice at the time of installation was that there aren't really any street lights nearby, and apparently even the cloest one has been out for months.

 

So, I've got to find a way to get good enough night time performance out of the camera to be able to keep an eye on the car outside the house (approx. 3-4 metres away) and, if possible, a little further afield. I suggested installating a PIR floodlight, but since the problems are occurring at the front of the house it would probably get a lot of nuisance triggering and look a little too conspicuous.

 

You're probably getting the idea by now... I need suitable IR illumination for the camera. I've had a look through my CPC catalogue and a few web sites (including eBay) and there's a lot of choice. I've seen a few LED-based units and they seem like a fairly attractive solution given the low power consumption, no emission of visible light, and low price point. For example, CPC code SR04439 claims to be a 10m infra-red source for only £45. Now, I'm into electronics and I know the sort of performance LEDs provide in the visible spectrum, but haven't got a clue when it comes to IR. Would I be wasting my time with such a purchase? I'm on a budget, but I wouldn't want to waste money on something that isn't going to provide the performance increase I promise.

 

Then there's also the (what I assume are) more typical units that aren't based around LEDs. I don't claim to know how these work, but they seem to be the type used in most commercial applications and emit a small amount of red light in the visible spectrum. I'd imagine these perform better, but the higher initial and running costs make them slightly less attractive for this particular application.

 

In conclusion, what would you guys recommend? What sort of range can I expect and for what price? Does anyone have any examples to show the difference between camera with and without IR illumination?

 

Cheers,

 

Matthew

[Airick 0]

IR illuminators generally come in two different types. Near-Covert is light at 850 nm. This is close to the visible "red" ligth and therefore you get can see a slight red in the LED. Covert IR is light at 950 nm and does not give itself away with the reddish glow.

 

One thing to check on your specs is the angle of illumination and range. If the car is 3-4 m away, then you might have trouble illuminating it all and you could end up with a useless spotlite on one point of the car and not be able to see anything around it.

 

You could just install a motion activating floodlight. It would have the benefit of illuminating enough of the area for your cameras as well as perhaps detering the vandalism.

[rory 0]

Hi, also read my post on this thread.

http://www.cctvforum.com/viewtopic.php?t=4172

[Cooperman 0]

Hi electronicsuk and welcome,

 

You've had some good information from the chaps already, but I thought I'd just quickly mention a couple of other points that might be of interest.

 

Here in the U.K., the two most popular "bulbed" IR illuminators are filtered for 715nM (bright red glow) and 830nM (dull red glow). illuminators providing outputs between 850 and 950 nM become increasingly covert as the number increases, and most higher frequency lighters are now LED based rather than bulb fitted.

 

I'm guessing that if you've used a Wickes camera (without knowing which one), it is going to be fairly basic, and is unlikely to have any significant IR response. In other words, you'd probably need a reasonable quantity of IR light (even at a lower frequency), just to get anything useful on screen.

 

As a suggestion, it may be worth considering keeping a low level maintained 'white light' illuminator on, perhaps using a 60w bulb. Hot filaments give out shed loads of IR, and whilst the surrounding area may not look terribly well lit to the human eye, the camera should see it very clearly.

 

Certainly for such a short distance to view, you won't need anything hugely impressive.

[electronicsuk 0]

Thanks guys. A security light isn't really the preferred option as the system is supposed to be relatively covert, but if its the only sensible option then it doesn't leave me with a lot of choice. I've taken a look through the spec sheet for the camera and there's no mention of IR response, the closest thing is the light level required for operation of the camera in lux.