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Help me please ......Project Design question

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installer2001

New Member
hello Guys,
plz help me urgently


Query is that "How IR can pass through Human finger or Ear Lobe "


Suppose that we have IR transmitter & receiver .

(IR TRANSMITTER) then i place my finger (or ear lobe) in between and then i place IR receiver .
So none of the light is able to pass through my finger(or ear lobe) and the receiver is in cutoff bcoz no IR pass through from my finger (or ear lobe) .

Sir plz tell me any IR transmitter that will able to penetrate the human ear lobe.
bcoz ear lobe is most sensitive part of human body without any bone
Is there any higher intensity IR available ,if yes then from where.
Sir if at output i get only few millivolts then it will be more than enough for me....

I am currently using LED55(IR transmitter ) but not getting desired result .
 

mneary

New Member
My experience is that IR passes easily through my finger or ear lobe or anywhere there is no bone in the way. My TV remote is not as effective (it works at 1 m instead of 10 m) but it works.

Infrared transmission is apparently measured to estimate blood flow. Ratio of IR transmission to Red transmission gives an estimation of oxygen (or is it C02?). Lots of info can be found through Google.
 
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installer2001

New Member
Respected Mneary


Can u plz tell me any IR which can pass earlobe or human finger...
You please plz tell me the name so that i can buy it...
Plz give me the link

IR working at 940 nm will be preferred...
 

mneary

New Member
What do you need? IR is an abbreviation for InfraRed. 940 nm is within that classification. LED55 is a 940 nm GaS device; here is its data sheet http://www.fairchildsemi.com/ds/LE/LED55C.pdf . You cannot see 940 nm but it can be seen by your cell phone camera or maybe your cat.

p.s. If you have a full keyboard please use it.
 
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installer2001

New Member
Please reply

Sir arr you sure that LED55 IR will be able to pass from my ear lobe...Is any anyway to increase it's power output so that it can pass from my earlobe...
Please please reply ..
 

mneary

New Member
LED55 will pass through your earlobe. But you need to be looking with a receiver that can see it. What are you using?
 

audioguru

Well-Known Member
Most Helpful Member
An LDR is hopeless as a receiver. It might not even respond to IR.
Why not use an IR receiver IC or an IR photo-diode with a preamp or an IR photo-transistor??
 

installer2001

New Member
Can any body guide me in selecting appropriate IR receiver for my circuitry.

My transmitter(LED 55) operates at 38KHZ and LED55 operates at 940nm wavelength

Plz guys help me ...
 

john1

Active Member
I think that identical LEDs can be used as senders and receivers for each other,
but i havent tried it.
See what others say about it.

John :)
 

Torben

Well-Known Member
I think that identical LEDs can be used as senders and receivers for each other,
but i havent tried it.
See what others say about it.

John :)
They can, but you need more of a preamp on the receiving end. Unless there's a reason to do this it's probably easier to just use a suitable IR phototransistor or photodiode.


Torben
 

installer2001

New Member
Guys ......
I am planning to use PL-IRM0101-3 as IR receiver .....

Torben what u say.......

Should i use Identical LED's for transmitter and receiver or should i use

LED 55 as IR transmitter and PL-IRM0101-3 as IR reciver....
 

audioguru

Well-Known Member
Most Helpful Member
An LED has an extremely low output when it is used as a receiver. You can't use it in your circuit.
 

installer2001

New Member
MR Blueroom electronics can u plz tell me which IR phototransistor should i use.....
Plz can u mention some IR phototransistors...

Thz in advance..
 
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