Robot Sensor(Tept5600) detecting a LED from max 2 a 3m

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Hey,

I'm working on an project on school with robots they use sensors(Tept5600) for detecting light like White Led. The problem is that i can't use Ifrared because it will use for something else and the teacher banned me to use the IR. So i can only use the Ambient light sensor(Tept5600). The problem is that i must detect a LED at 2 a maximum 3 meter but my sensor detect a lot of ambient light and i only can use the TEPT5600. So i did some research and if i blink my LED on and OFF at een frequency of 1 kHz can i use a filter after the ambient light sensor like HPF or BPF?

Someone an idea about this?
sry about my english.

Grtz
Killa
 

What would you like to achieve from the project?

I mean why are you applying 1kHz to LED?

And why you need HPF or LPF?
 

chuckey said:
That's exactly what I would do, try to avoid a multiple of your mains frequency, as flourescent lighting "blinks" at 2 X Fmains, so 975 HZ for 50 HZ mains or 990 for 60 HZ.
Frank
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sounds like the best way, though another way might be to measure the ambient light, pulse the LED[to get more contrast between LED on and minor ambient light changes], and detect the difference
 

It might pay to experiment with a tube, and/or a magnifying lens. The goal is to get only light from the led on your sensor, and screen out ambient light.

This has a disadvantage because you will then have a limited field of view. The robot might need to pivot around, to search for the led. So it may not be practical.
 

Thanks for your reply. The frequency was an example. I thougt if i blink a LED at some frequency maybe i can detect him when i use a Low pass filter. I will try it today.

The robot must search the light automatically. He will advanced than turn around.
The problem is detecting light blinking or not, only with this kind of sensor.
Using two the same sensors and then the difference won't be a good idea. One will get sunlight etc.

I try a lot of test with my board but no result for the moment. If you have any idea let met know. I have already reduce the grandient to 5 a 10 degrees but it kept sunlight and daylight. How can i only detect the light of the LED
 

If you use a pulsating LED with a suitable BANDPASS filter it might work. Sunlight would give DC or a very low frequency out of the detector, that is why a low pass filter is no good. A high pass might be better. The sunlight might be driving the detector diode into saturation, i.e. if it gets more light it will not give any more output. If you suspect this is happening try operating another detector with a filter on it, it will not give so much output, but you might get some of your pulsating frequency through it. If you choose a colour, say blue and use a blue filter and a LED which gives a lot of blue light and a detector with a blue filter and high output in the blue spectrum, it could help.
Frank
 


Hey,

Thanks Frank for your reply. I will blink my led at an frequency like 100 Hz. After my sensor i will use an BPF(opamp,...). I must use a white led and the detector TEPT5600. (5V dark and 0V sunlight/daylight). I hope i wil get only light of my LED and the voltage increase or decrease dependent of my LED

LED----------------3m------------------>Sensor and behind BPF.
Is it this what you mean?
 
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