Hello
For a project I am searching for the right PIR sensor.
The aim is to sense motion in a very small range, approximately about 15cm.
Since most PIR sensors measuring wider rangers (up to 7ft) I am wondering which PIR sensor is suitable for my project.
Sincerely,
Castel
Just a thought. try a pir sensor with the freznel lens removed.
You might be able to limit the range by attenuating with some sheets or objects.
Many common PIR detectors use resistors and a pot to allow for adjustable sensitivity. You might be able to 'hack' the board and change these values to further reduce sensitivity, but I'm not sure about 15cm. Perhaps a filter as suggested.
What are you trying to do? There may be a better approach.
OldSteve:
Many common PIR detectors use resistors and a pot to allow for adjustable sensitivity. You might be able to 'hack' the board and change these values to further reduce sensitivity, but I'm not sure about 15cm. Perhaps a filter as suggested.What are you trying to do? There may be a better approach.
For my project a LED is lightning. When my hand moves in front of a sensor (range about 15 cm or less) the LED if off. When the hand is further away, (more than 15cm) the sensor can not respond to this.
castel:
For my project a LED is lightning. When my hand moves in front of a sensor (range about 15 cm or less) the LED if off. When the hand is further away, (more than 15cm) the sensor can not respond to this.
An ultrasonic 'ping' sensor might be more suited to this. Beacause it actually measures distance, unlike a PIR sensor, you'd get bettter results. But a ping sensor doesn't work at distances smaller than several cm. You could probably rely on it for distances between 5cm and 15cm though. They're very cheap, and easy to use, so it might be worth buying one to test and see if it suits your needs.
When using an US distance sensor I am facing one more problem. It's unable to get the sound waves through tissue. Is there any posibility that an infrared range sensor will go through transparant plastic?
castel:
When using an US distance sensor I am facing one more problem. It's unable to get the sound waves through tissue.
No, it'll bounce off or be absorbed by solid objects. You didn't mention that there would be something solid in the way.
Is there any posibility that an infrared range sensor will go through transparant plastic?
Yes. (Look at how well infra-red remote controls work, with plastic on the front of the remote and in front of the detector.) They might not be too effective at reflecting off your hand though. They work best with hard surfaces. So do ultrasonic sensors, but IR systems are worse in this regard. You'll need to test one and see if it's performance is acceptable. I considered suggesting IR earlier, but opted for ultrasound because it woud be more reliable for your purpose.
OldSteve:
No, it'll bounce off or be absorbed by solid objects. You didn't mention that there would be something solid in the way.
Yes. (Look at how well infra-red remote controls work, with plastic on the front of the remote and in front of the detector.) They might not be too effective at reflecting off your hand though. They work best with hard surfaces. So do ultrasonic sensors, but IR systems are worse in this regard. You'll need to test one and see if it's performance is acceptable. I considered suggesting IR earlier, but opted for ultrasound because it woud be more reliable for your purpose.
Thanks in advance for the advice.
Reliabilitity is not realy the problem. The motion just has to be detected closeby. In fact i should be able to make a sensor with an LED and IR receiver going through transparant plastic?
Best regards
castel:
Thanks in advance for the advice.
Reliabilitity is not realy the problem.
It will be if the method doesn't always work.
The motion just has to be detected closeby. In fact i should be able to make a sensor with an LED and IR receiver going through transparant plastic?
I already answered this once, in my last post:
OldSteve:
Yes. (Look at how well infra-red remote controls work, with plastic on the front of the remote and in front of the detector.)
Thank you for the helpfull advice.
Btw I have one more question considering distance sensors.
Is there existing an infrared sensor measuring upto 200 cm? The maxiumum range SHARP sensors providing is 150cm.
Best regards