Hi
I have bought a Kemo IR floodlight kit which I aim to illuminate an Owl nesting box and monitor it with an adapted USB webcam (IR filter removed) plugged into a Raspberry Pi.

What I am unsure about is will I need all the IR "light" from the kit? So I was thinking i could adapt it and have a separate power supply to each string of emitters. If I do this what input voltage should I use? The kit states that I need a 12v supply for the whole kit but as I think the strings are in parallel if I only use 6 of the strings should I reduce the input voltage down to 9v? I have attached a picture of the board if that helps.

My plan would be not to solder one side of the resistor to the board and instead solder each +ve/anode? supply to it instead and have a common -ve/cathode?

Cheers


David

 

The strings are in parallel, keep the supply at 12v.

Also, how sure are you that the owls wont be disturbed by the IR? People can see cheap IR LED's, I imagine an owl would be much more sensitive.

 

thats just 8 circuits in parallel with its own resistor for each series string.. simple.
The supply voltage must be greater than the combined Vf of each LED in the series string.
You can wire up 1 to max 8 strings..You still need the 12V supply.. But as you fill more circuits the "current" requirement of the power supply will increase..

 

Hi thanks for that. That will be much easier and I can probabably use a DIP switch to adjust the "light"

When you say people can see IR LED's do you mean the red glow?

David

 

some birds that can see light in the ultraviolet spectrum but can't see into the IR spectrum. Their cones top out at 700nm..

 

I need to do a bit more research!

 

some birds that can see light in the ultraviolet spectrum but can't see into the IR spectrum. Their cones top out at 700nm..

Seems like it would be an incredible advantage for an owl to see warm rodents in the dark. Can any animal "see" into the IR? (I don't count snakes as really seeing heat so much as sensing it.)

 

See page 710 and following of this old book.

http://jgp.rupress.org/content/23/6/709.full.pdf+html

 

See page 710 and following of this old book.

http://jgp.rupress.org/content/23/6/709.full.pdf+html

I like the first paragraph of section II when they simply say the previous investigator's results are horse hockey without saying how it was proven to be horse hockey. Quite unusual for a technical journal in those days. Usually, they would wait for the end, once the full body of new work is properly played.

 

Great reference!

It answers my question as to why IR vision is not more common in nature:

"They found that the tawny owl's eye which gave retinal potentials when exposed to ordinary light, failed to show any potential when illuminated by the infrared radiation from a black body at temperatures between 40° and 400° C. Moreover, they demonstrated that the lens and vitreous humour of the eye are opaque to these radiations, as is to be expected from their high water content."

 

Seems like it would be an incredible advantage for an owl to see warm rodents in the dark. Can any animal "see" into the IR? (I don't count snakes as really seeing heat so much as sensing it.)

Pit viper snakes "see" the IR radiation from a warm body with two single-pixel unfocused thermal sensors, one in each of the pits on each side of the head to give stereoscopic sensing. Of course the resolution of the image is rather low but I imagine that can get a good sense of the size of the warm object by moving the head slightly side-to-side and up-and-down. I've seen videos of a pit viper, with his eyes blindfolded, hitting the center of a balloon filled with warm water suspended in front of him.