IR wall detection -- physical setup. - Electronic Circuits Projects Diagrams Free

**3v0** · 16th April 2008, 02:28 AM

EDIT:
After posting this I realized that most of what I am asking is impossible to answer due to the charistics of specific parts. Just the same any pointers are welcome.
--------------------------------------------------------------------------------------------------------------------

I need to demo how this at school soon. I have a receiver on a breadboard and code on the processor that detects the low from the receiver. So far I have only tested it with a TV remote which puts out too strong an IR signal. I can bounce it off the ceiling and it still sees it. (That is expected)

I could come up with this by working with it but if anyone can give me a starting point it would be very helpful. Could save me some time.

The questions I have is about setting up the IR LEDs. I am going to be driving them with a PIC port pin. How much of a resistor is required to reduce the current through each LED such that it will have enough but not too much IR. I know I could also cut the duty cycle of the 40KHz back to less then 50%. If ones goes that route how low of a duty cycle will the TSOP receiver work with?

I plan to use 2 IR LEDs with a receiver in the middle \ | / only one LED will be active at a time. The idea is to check to the left and the right.

Currently I have 3 choices of LEDs
17 degree angle
25 degree angle
Radio Shack Clear unknown angle
Radio Shack Grey unknown angle

Which LEDs and what angle between the detector and the receiver.

**Nigel Goodwin** · 16th April 2008, 06:52 AM

Quote:

Originally Posted by 3v0

EDIT:
After posting this I realized that most of what I am asking is impossible to answer due to the charistics of specific parts. Just the same any pointers are welcome.
--------------------------------------------------------------------------------------------------------------------

I need to demo how this at school soon. I have a receiver on a breadboard and code on the processor that detects the low from the receiver. So far I have only tested it with a TV remote which puts out too strong an IR signal. I can bounce it off the ceiling and it still sees it. (That is expected)

I could come up with this by working with it but if anyone can give me a starting point it would be very helpful. Could save me some time.

The questions I have is about setting up the IR LEDs. I am going to be driving them with a PIC port pin. How much of a resistor is required to reduce the current through each LED such that it will have enough but not too much IR. I know I could also cut the duty cycle of the 40KHz back to less then 50%. If ones goes that route how low of a duty cycle will the TSOP receiver work with?

I plan to use 2 IR LEDs with a receiver in the middle \ | / only one LED will be active at a time. The idea is to check to the left and the right.

Currently I have 3 choices of LEDs
17 degree angle
25 degree angle
Radio Shack Clear unknown angle
Radio Shack Grey unknown angle

Which LEDs and what angle between the detector and the receiver.

Check my website that includes just what you're looking for

http://www.lpilsley.com/cybot/radar.htm

and the original site

http://users.frii.com/dlc/

**3v0** · 16th April 2008, 09:21 AM

Thanks Nigel.

16th April 2008, 02:28 AM	(permalink)
3v0 Moderator Blog Entries: 3	IR wall detection -- physical setup. EDIT: After posting this I realized that most of what I am asking is impossible to answer due to the charistics of specific parts. Just the same any pointers are welcome. -------------------------------------------------------------------------------------------------------------------- I need to demo how this at school soon. I have a receiver on a breadboard and code on the processor that detects the low from the receiver. So far I have only tested it with a TV remote which puts out too strong an IR signal. I can bounce it off the ceiling and it still sees it. (That is expected) I could come up with this by working with it but if anyone can give me a starting point it would be very helpful. Could save me some time. The questions I have is about setting up the IR LEDs. I am going to be driving them with a PIC port pin. How much of a resistor is required to reduce the current through each LED such that it will have enough but not too much IR. I know I could also cut the duty cycle of the 40KHz back to less then 50%. If ones goes that route how low of a duty cycle will the TSOP receiver work with? I plan to use 2 IR LEDs with a receiver in the middle \ \| / only one LED will be active at a time. The idea is to check to the left and the right. Currently I have 3 choices of LEDs 17 degree angle 25 degree angle Radio Shack Clear unknown angle Radio Shack Grey unknown angle Which LEDs and what angle between the detector and the receiver. __________________ search engine for electronic parts Junebug USB PIC programmer kit., USB Bit Wacker, Homepage The 15 Minute Printed Circuit Board! (+drill time) Last edited by 3v0; 16th April 2008 at 03:05 AM.

16th April 2008, 09:21 AM	(permalink)
3v0 Moderator Blog Entries: 3	Thanks Nigel. __________________ search engine for electronic parts Junebug USB PIC programmer kit., USB Bit Wacker, Homepage The 15 Minute Printed Circuit Board! (+drill time)

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