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Basically, I have this line sensor. It is designed to distinguish black and white lines. It detects white surface and gives me digital 1 as output and 0 in case of black. But the surface need to be too close to it.

However, as it uses infra-red sensors, I wanted to use this sensor as a proximity sensor, to tell me if there is a white surface near it. Is it possible to do this? I think the only problem here is, that we need to increase its range of giving 1. Currently, it gives 1 only when white surface is too close to the sensors. I want 1 even if the white surface is there at a bit more distance.

Also there is an adjustable screw there to adjust something, under which POT is written. I am working on Arduino.

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  • \$\begingroup\$ Is the target a white surface? What range do you need to detect the target? \$\endgroup\$ – gbulmer Sep 11 '14 at 18:02
  • \$\begingroup\$ yes, white walls. range around 5 cms (not precise) \$\endgroup\$ – user53058 Sep 12 '14 at 15:21
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The line sensor you linked operates using an IR LED and phototransistor, and the specifications state that the range is adjustable from 10 to 50 mm.

To increase the range further, you would need to use a more powerful IR emitter and/or a more sensitive IR detector. The angle of view (sort of a misnomer when talking about infrared) would need to be considered as well. Some sensors employ plastic or glass lenses to focus and achieve greater ranges.

A higher-power emitter would probably require more power than the circuit is currently designed to supply, so you would also have to modify the current-limiting resistor and/or the supply voltage.

IR proximity sensors are designed to detect a certain threshold of reflected IR light. When a object that reflects IR is near, the phototransistor base current goes up. When the desired threshold is reached, the circuit produces "HIGH" (1) output. The line-following sensor is the same basic idea.

You might be able to use another sensor that is designed as a proximity sensor and already has the range you are looking for. It will require some experimentation and calibration, as the line or surface you are trying to detect will probably be more reflective than, say, a human.

Also keep in mind that longer range detection can incur additional problems, such as other sources of infrared light. If you're trying to detect a line outdoors, sunlight will raise the amount of detected IR across the board, and you'll have to change the detection threshold.

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