Reading the intensity of an IR Led using a PNA4601M IR Recei

B

BurningFuses

Guest
Hello,
I'm trying to detect if an IR Led is on and if it is how intense is the light.
For this purpose I tried to use a PNA4601M IR Receiver (http://parallax.com/product/350-00014) that I bought from Parallax a while ago.
I thought the I could simply connect the Vcc of the IR Receiver to 5v, the GND and read the voltage out through the Vout. The higher the voltage, the stronger the IR Light shinning on the IR Receiver. But that is not what happened.
After applying 5V to the Vcc, connecting the GND and reading the output (Vout), I get 5V (a bit lower than the input), even with the IR Led turned off.
What am I missing here? Any clues?
Thanks a lot,
BurningFuses
 
On Wed, 6 Nov 2013 09:42:45 -0800 (PST), BurningFuses
<cassiano@gmail.com> wrote:

Hello,
I'm trying to detect if an IR Led is on and if it is how intense is the light.
For this purpose I tried to use a PNA4601M IR Receiver (http://parallax.com/product/350-00014) that I bought from Parallax a while ago.
I thought the I could simply connect the Vcc of the IR Receiver to 5v, the GND and read the voltage out through the Vout. The higher the voltage, the stronger the IR Light shinning on the IR Receiver. But that is not what happened.
After applying 5V to the Vcc, connecting the GND and reading the output (Vout), I get 5V (a bit lower than the input), even with the IR Led turned off.
What am I missing here? Any clues?

That component is intended to work with a 38 KHz modulated signal. It
has an internal bandpass filter in order to reduce the sensitivity of
the device to constant sources -- like your IR LED. If you hold a
typical IR remote control up to it and trigger the remote with a
repeating signal (like, say, volume down) then you should see a net
deflection with your multimeter. This
https://www.sparkfun.com/products/10266 over at Sparkfun isn't
identical to yours but the datasheet over there will give you an idea
of what the output looks like, when presented with the modulated pulse
train from a remote control's output.

Something like https://www.sparkfun.com/products/241 is an IR detector
without the added bandpass filter, and so it will respond to a
constant input signal.

And shame on Parallax for not providing a link to a datasheet!

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com
 
On Wed, 06 Nov 2013 09:42:45 -0800, BurningFuses wrote:

Hello,
I'm trying to detect if an IR Led is on and if it is how intense is the
light.
For this purpose I tried to use a PNA4601M IR Receiver
(http://parallax.com/product/350-00014) that I bought from Parallax a
while ago.
I thought the I could simply connect the Vcc of the IR Receiver to 5v,
the GND and read the voltage out through the Vout. The higher the
voltage, the stronger the IR Light shinning on the IR Receiver. But that
is not what happened.
After applying 5V to the Vcc, connecting the GND and reading the output
(Vout), I get 5V (a bit lower than the input), even with the IR Led
turned off.
What am I missing here? Any clues?
Thanks a lot,
BurningFuses

You want to look for a plain old IR phototransistor or photodiode. A
phototransistor is probably more what you want (it'll have better gain).

Don't get the floor-sweepings that Radio Shack sells unless your needs
are very modest -- go shopping at DigiKey or Mouser and get something
that doesn't need to be pounded with light to detect something.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
 
"BurningFuses"

Hello,
I'm trying to detect if an IR Led is on and if it is how intense is the
light.

** A digital camera will do that.


For this purpose I tried to use a PNA4601M IR Receiver

** The full name is " modulated IR digital code receiver ".


BTW: Do you think "steak sauce" is made from steak?



.... Phil
 
On Wednesday, November 6, 2013 12:42:45 PM UTC-5, BurningFuses wrote:
Hello,

I'm trying to detect if an IR Led is on and if it is how intense is the light.

For this purpose I tried to use a PNA4601M IR Receiver (http://parallax.com/product/350-00014) that I bought from Parallax a while ago.

I thought the I could simply connect the Vcc of the IR Receiver to 5v, the GND and read the voltage out through the Vout. The higher the voltage, the stronger the IR Light shinning on the IR Receiver. But that is not what happened.

After applying 5V to the Vcc, connecting the GND and reading the output (Vout), I get 5V (a bit lower than the input), even with the IR Led turned off.

What am I missing here? Any clues?

Thanks a lot,

BurningFuses

My favorite way for detecting light is to stick a photodiode across the uA current input leads on my DMM. Bang you're done.. and if you know the wavelength then you have a decent measure of the light intensity. (Assuming access to the photodiode data sheet.)

George H.
 
On Thursday, November 7, 2013 11:16:27 AM UTC-5, John Larkin wrote:
On Thu, 7 Nov 2013 06:22:30 -0800 (PST), George Herold <gherold@teachspin..com

wrote:
On Wednesday, November 6, 2013 12:42:45 PM UTC-5, BurningFuses wrote:
Hello,

I'm trying to detect if an IR Led is on and if it is how intense is the light.



For this purpose I tried to use a PNA4601M IR Receiver (http://parallax.com/product/350-00014) that I bought from Parallax a while ago.



I thought the I could simply connect the Vcc of the IR Receiver to 5v, the GND and read the voltage out through the Vout. The higher the voltage, the stronger the IR Light shinning on the IR Receiver. But that is not what happened.
snip
My favorite way for detecting light is to stick a photodiode across the uA current input leads on my DMM. Bang you're done.. and if you know the wavelength then you have a decent measure of the light intensity. (Assuming access to the photodiode data sheet.)

George H.

For low levels, use the voltage leads. A 10 meg input impedance voltmeter is an
ammeter with sensitivity of 100 pA per millivolt. Even cheap meters can reliably
measure nanoamp currents.

OK.. I guess that's for *really* low light levels! I futzed around to get 1uA of photocurrent...(Pretty dark.) On the volt/ milli volt scale this registered as ~200mV...
(One might worry about the input impedance of the meter on the milli-volt scale... I know some go into a high Zin mode.)

So the diode had an resistance of ~200k ohm... Hmm why not 25mV/1uA = 25k ohm?
(I seem to be confusing myself.) Yeah, I know, with light shinning on it the I-V curve is displaced downwards.

I tried a smaller area PD.. more light for 1uA.. and now that gives 230mV in voltage mode.
(scratch scratch...time for lunch.)

George H.
--



John Larkin Highland Technology Inc

www.highlandtechnology.com jlarkin at highlandtechnology dot com



Precision electronic instrumentation

Picosecond-resolution Digital Delay and Pulse generators

Custom timing and laser controllers

Photonics and fiberoptic TTL data links

VME analog, thermocouple, LVDT, synchro, tachometer

Multichannel arbitrary waveform generators
 
On Thu, 7 Nov 2013 06:22:30 -0800 (PST), George Herold <gherold@teachspin.com>
wrote:

On Wednesday, November 6, 2013 12:42:45 PM UTC-5, BurningFuses wrote:
Hello,

I'm trying to detect if an IR Led is on and if it is how intense is the light.

For this purpose I tried to use a PNA4601M IR Receiver (http://parallax.com/product/350-00014) that I bought from Parallax a while ago.

I thought the I could simply connect the Vcc of the IR Receiver to 5v, the GND and read the voltage out through the Vout. The higher the voltage, the stronger the IR Light shinning on the IR Receiver. But that is not what happened.

After applying 5V to the Vcc, connecting the GND and reading the output (Vout), I get 5V (a bit lower than the input), even with the IR Led turned off.

What am I missing here? Any clues?

Thanks a lot,

BurningFuses

My favorite way for detecting light is to stick a photodiode across the uA current input leads on my DMM. Bang you're done.. and if you know the wavelength then you have a decent measure of the light intensity. (Assuming access to the photodiode data sheet.)

George H.

For low levels, use the voltage leads. A 10 meg input impedance voltmeter is an
ammeter with sensitivity of 100 pA per millivolt. Even cheap meters can reliably
measure nanoamp currents.




--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators
 
On Thu, 7 Nov 2013 10:10:21 -0800 (PST), George Herold
<gherold@teachspin.com> wrote:

On Thursday, November 7, 2013 11:16:27 AM UTC-5, John Larkin wrote:
On Thu, 7 Nov 2013 06:22:30 -0800 (PST), George Herold <gherold@teachspin.com

wrote:
On Wednesday, November 6, 2013 12:42:45 PM UTC-5, BurningFuses wrote:
Hello,

I'm trying to detect if an IR Led is on and if it is how intense is the light.



For this purpose I tried to use a PNA4601M IR Receiver (http://parallax.com/product/350-00014) that I bought from Parallax a while ago.



I thought the I could simply connect the Vcc of the IR Receiver to 5v, the GND and read the voltage out through the Vout. The higher the voltage, the stronger the IR Light shinning on the IR Receiver. But that is not what happened.
snip
My favorite way for detecting light is to stick a photodiode across the uA current input leads on my DMM. Bang you're done.. and if you know the wavelength then you have a decent measure of the light intensity. (Assuming access to the photodiode data sheet.)

George H.

For low levels, use the voltage leads. A 10 meg input impedance voltmeter is an
ammeter with sensitivity of 100 pA per millivolt. Even cheap meters can reliably
measure nanoamp currents.

OK.. I guess that's for *really* low light levels! I futzed around to get 1uA of photocurrent...(Pretty dark.) On the volt/ milli volt scale this registered as ~200mV...
(One might worry about the input impedance of the meter on the milli-volt scale... I know some go into a high Zin mode.)

Most stay at 10M, although some bench meters can optionally go hi-z. A
bigger issue is that, if you want to measure diode current in PV mode,
you need the voltage to be low, probably no more than 100-200 mV
maybe. At higher voltage, the diode conducts and gobbles up its own
current.

Use the current range if it has enough resolution.



--

John Larkin Highland Technology, Inc

jlarkin at highlandtechnology dot com
http://www.highlandtechnology.com

Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom laser drivers and controllers
Photonics and fiberoptic TTL data links
VME thermocouple, LVDT, synchro acquisition and simulation
 
On Thursday, November 7, 2013 7:18:52 PM UTC-5, John Larkin wrote:
On Thu, 7 Nov 2013 10:10:21 -0800 (PST), George Herold


snip

OK.. I guess that's for *really* low light levels! I futzed around to get 1uA of photocurrent...(Pretty dark.) On the volt/ milli volt scale this registered as ~200mV...

(One might worry about the input impedance of the meter on the milli-volt scale... I know some go into a high Zin mode.)



Most stay at 10M, although some bench meters can optionally go hi-z. A
bigger issue is that, if you want to measure diode current in PV mode,
you need the voltage to be low, probably no more than 100-200 mV
maybe. At higher voltage, the diode conducts and gobbles up its own
current.

Use the current range if it has enough resolution.
OK this is nice.. here’s the forward voltage drop vs bias current.
Vf is for the PD I used yesterday ~200mV at 1 uA. The PIN-44 is one we commonly use...about the same area (for comparison.) There’s something like 100 ohms of resistance in series with the diode drop... but it’s non-linear. (less resistance at 10mA)

https://www.dropbox.com/s/qx199i6pcyhlan3/PIN44_VF.BMP

For these PD’s you’ve got to be below ~100mV to not have any current sucked up by the diode. But for low light levels you could just use the logarithmic behavior of V to get an estimate of the light intensity. (You’d have to do the I-V of ‘your’ PD first.)

George H.

--



John Larkin Highland Technology, Inc



jlarkin at highlandtechnology dot com

http://www.highlandtechnology.com



Precision electronic instrumentation

Picosecond-resolution Digital Delay and Pulse generators

Custom laser drivers and controllers

Photonics and fiberoptic TTL data links

VME thermocouple, LVDT, synchro acquisition and simulation
 

Welcome to EDABoard.com

Sponsor

Back
Top