Thanks Matt, that's very helpfulMattHawkinsUK wrote:Take a look at my post :
http://www.raspberrypi-spy.co.uk/2013/1 ... umination/
The 48 LED type devices would probably suit your purposes. I would buy a cheap one and experiment.
According to http://www.gizmology.net/LEDs.htm : A fairly typical "bright" IR LED will put out about 27 mW/sr. Now there are 4*pi steradians in a sphere. At a distance of 1 cm from that LED, you get 27 mW/cm^2 but it falls off as 1/r^2 so at 2 cm away, you have only 27/4 or 6.75 mW/cm^2, and at 4 cm you have 27/16 or 1.69 mW/cm^2. So if you have an illuminator with 40 such LEDs, you do want to stay at least 10 cm away from it to be within the TLV value for long-term exposure. In other words, don't clamp such an illuminator source to the rail of the crib, but mounting it somewhere out of reach should be fine. But of course, such a thing should always be mounted out of reach, for several other reasons! such as the strangulation hazard from the power cord getting around the neck.The ACGIH publish the TLV (Threshold Limit Values) for various physical agents; they recommend a TLV of 10 mW/cm2 for the irradiance of near Infra-Red radiation under
conditions of viewing for longer than 16 mins.
can you point me in the direction of the retrofit bulb you are using please?batfastad wrote:I'm hoping to do exactly the same thing to replace a D-Link DCS-932L which we've been using as a baby monitor for about a year. This D-Link works well but having to use a nasty browser plugin (ActiveX or Java) is annoying, and connecting to the MJPEG stream directly with VLC or something is extremely unreliable. I want something that I can hook up to with XBMC or any streaming media player, so presumably an RTSP stream of some sort. I've seen a few bits about this in the forums.
The DCS-932L (http://www.dlink.com/uk/en/home-solutio ... oud-camera) produces enough illumination but only appears to have 4 iR LEDs, glowing a dim red colour.
Does anyone have any info on whether it's possible to obtain and then power similar iR LEDs directly from the Pi?
Presumably there's a maximum amount of power that would be available for these? I was hoping to be using a USB wifi adaptor and possibly a small microphone and temperature sensor as well.
It would be great to have this powered by a single cable but I don't have much practical electronics knowledge. I'm not afraid of learning a bit if someone can point in the direction of parts needed and the best way to power from the Pi.
I use this one (web page in German language, can be switched to Spanish tho)keithj69 wrote: can you point me in the direction of the retrofit bulb you are using please?
But why can't the Raspberry organization post the designed frequency response of their product? Is this too much to ask that they provide this information?jbeale wrote:I haven't done this, but I'd be willing to bet the peak sensitivity is somewhere around 700 nm, because that's usually the case for any CMOS sensor. It will be lower as you go to 900 nm and goes to zero between 1000 to 1100 nm which is the practical limit for silicon sensors. Do an image search for "CMOS spectral response" for some example graphs.
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