I used a photo diode with peak sensitivity to wavelength of 900nm to detect flash light.
First i tried an LED with wavelength 450nm and it required a minimum of 50us LED on time to trigger the circuit.
Now with an apple ipod, it took ~7ms.
I have got not idea like what kind of led is used in an ipod or its internal led control circuitry.
I am aware of the fact that the intensity & wavelength of LED used plays a key role in the detection.
If anybody could shed more light on this, it could help understand and provide a sensible explanation to all these stuffs.
Thanks & Regards,