Hi all
I'm currently working on a project for my car and need some advice on using infrared led's.
What I would like to do is place lights in the door pockets of my car. The lights would then be triggered when an object (or hand) is placed inside the door. It would then stay on for a certain amount of time, before switching off.
How I planned on implementing this is by placing an infrared led and phototransistor on one end of the door pocket. I then wanted the light reflected off the object to be picked up the phototransistor and switch on the lights. (the system needs to react to a change in ir light, not merely the detection of it)
All I need to know, is the following:
1. Can I use just one ir-led for my purposes (the maximum distance from the ir-led to the object it reflects off would be about 45cm).
2. Does the ir-led have to be modulated at 38khz or could I do it without modulation? (I know ambient ir light may affect the sensor, but I think its location may be sheltered enough to avoid this problem). What I'm asking is, would modulating have any other benefit besides protecting against ambient IR light?
3. I've done some experimenting with a single ir-led, and reflected the light off my hand onto the transistor, but the current is extremely small (could not measure it at the time but probably less than a milliamp). A reflective object works much better, but I need it to work by reflecting off my hand. I have not tried to use a darlington to increase it yet, but would there be any other suggestions besides this? (perhaps an ir-phototransistor isn't suitable for my purposes at all?)
The ir-led I am using:
https://www.fort777.co.za/index.php?main_page=product_info&products_id=6075
Phototransitor:
https://www.fort777.co.za/index.php?main_page=product_info&products_id=6076
Could this be a better alternative?:
https://www.fort777.co.za/index.php?main_page=product_info&products_id=7206
I dont have any experience working with infrared systems, so I'm open to suggestions.
Thanks
I'm currently working on a project for my car and need some advice on using infrared led's.
What I would like to do is place lights in the door pockets of my car. The lights would then be triggered when an object (or hand) is placed inside the door. It would then stay on for a certain amount of time, before switching off.
How I planned on implementing this is by placing an infrared led and phototransistor on one end of the door pocket. I then wanted the light reflected off the object to be picked up the phototransistor and switch on the lights. (the system needs to react to a change in ir light, not merely the detection of it)
All I need to know, is the following:
1. Can I use just one ir-led for my purposes (the maximum distance from the ir-led to the object it reflects off would be about 45cm).
2. Does the ir-led have to be modulated at 38khz or could I do it without modulation? (I know ambient ir light may affect the sensor, but I think its location may be sheltered enough to avoid this problem). What I'm asking is, would modulating have any other benefit besides protecting against ambient IR light?
3. I've done some experimenting with a single ir-led, and reflected the light off my hand onto the transistor, but the current is extremely small (could not measure it at the time but probably less than a milliamp). A reflective object works much better, but I need it to work by reflecting off my hand. I have not tried to use a darlington to increase it yet, but would there be any other suggestions besides this? (perhaps an ir-phototransistor isn't suitable for my purposes at all?)
The ir-led I am using:
https://www.fort777.co.za/index.php?main_page=product_info&products_id=6075
Phototransitor:
https://www.fort777.co.za/index.php?main_page=product_info&products_id=6076
Could this be a better alternative?:
https://www.fort777.co.za/index.php?main_page=product_info&products_id=7206
I dont have any experience working with infrared systems, so I'm open to suggestions.
Thanks
