Which Camera

You could get the PiNoIR and add a filter for daylight use e.g.

for the best of both. Also requires one of these to do this for RPi-controlled filter swapping. :-)

I don't know if it's an option for you, but I bought a Logitech C920 camera for my Pi. This camera has its own H.264 encoder so it makes streaming a 1080P video through the Pi possible.

In message , Adrian writes

Thanks for the information.

A follow up question.

Would a standard Pi power supply (1 - 1.2A) be meaty enough to supply the Pi, the camera and an array of IR LEDs (say a couple of dozen).

Adrian

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No. The smallest IREDs listed at

have a forward current of 60mA. 24 * 60mA = 1.44A.

This ready-made unit is designed for 12V, 1.25A for up to 10m distance:

One way or another you'll need to get a fair amount of additional power to the lamp to illuminate the subject.

Thanks for the suggestion.

Adrian

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The current used by a LED is set by the circuit design , often a resistor. The current quoted in the spec is the maximum allowed. For the most efficient use of power from a 5volt USB supply connect the LEDs in parallel banks of 2 LEDs in series with appropriate resistors.

In message , robert writes

Thanks for the suggestion. I'll have to have a look at some datasheets, and do some calculations.

Adrian

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It's been a while now since I built stuff with LEDs but ISTR they used

15-25mA. Those were intended only as visible indicators though: your application will have to illuminate an area sufficiently to make the camera work, and I suspect that most IREDs are designed with higher output in mind. Datasheets may tell you a working current for optimal efficiency as well as a maximum. If you have a way of measuring the current and the IR output, you could plot your own curve.

It shows! I remember those days. Put 20mA in a green LED and it was just sufficiently lit to see its indication, when it was not in direct sunlight.

However, the times they have changed.

20mA in todays LED will make it shine like a torch with a brightness so high that it will hurt (or damage) your eyes when you look into it.

That's certainly true of those painfully bright blue LEDs, not so much for the red and green ones. If you need sufficient brightness for indicator lamp use, I'd say 10mA for red and green and 1mA for blue leds to maintain a reasonable balance when a blue led is part of mix.

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We never had no blue LEDs neither. Now everything comes with blue LEDs... taint natural... except Raspberry Pis... proper retro. :-)

The camera will be covering up to about 30ft.

Adrian

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Wireless keyboards originally eschewed LED indicators on the grounds of battery life. If, otoh, they'd known about blue LEDs they could have used proper indicator lamps for the Num lock, Caps lock and Scroll lock indicators and still offer a battery life of 8 to 16 months using a pair of AA alkaline cells.

Possibly some modern wireless keyboards do just that with blue LEDs. I haven't seen any since I haven't had any need to shop for a wirless keyboard so far.

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On Sun, 1 Dec 2013 14:38:40 +0000, Adrian declaimed the following:

That's likely to call for a very sensitive camera sensor AND a fairly massive IR array, presuming you are pulsing the array like an electronic flash. Consider: the electronic flash on visible light cameras is only rated for 7-15 feet depending on the ISO setting of the camera. Granted, your exposures are probably for much longer than that snapshot camera (unless you need to stop motion too)

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Probably not.

The Pi has approx. 200mA "spare" out of the GPIO connector. This limit is from the Pi itself taking some 200-400mA itself, leaving some to be shared between USB and the GPIO port. (That's 300mA, but you're really best off not pushing it) That limit is a rather hard limit caused by the 700mA polyfuse on the Pi's micro USB input.

The way to do it would be to power the camera separately via a powered USB hub (which could also power the Pi, if you only wanted one PSU), but do make sure the PSU powering the hub and everything else really is up to it. Sadly, a lot of the cheaper ones aren't.

Gordon