Wiimote Project » Hardware Support » IR Pens » Electronics 101 - Basics for those who want to make their own IR-Pen.
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 : Electronics 101 - Basics for those who want to make their own IR-Pen.  ( 151048 ) 0 and 3 Guests are viewing this topic.
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 « : May 06, 2008, 03:19:29 AM »

Wiimote friends!

This is a comprehensive knowledgebase on the 'need to know' issues when making your own IR-Pen. Covering basic eletronic principles and desirable IR-Led qualities. How you design and construct your pen is totally up to you. I have linked to my instructional videos as the bottom, but I also suggest you Google IR-Pen and read the Forum posts to find many other concepts.

Lesson 1: Use the correct power source
Make sure the minimum voltage from you power source exceeds the max voltage of the diode.
Example:
Vishay 6400 has a Maximum Forward Voltage = 1.6v
NIMH 1.2v Rechargeable AAA/AA Min Voltage = 0.8v
1.6/0.8 = 2
To ensure IR-LED is correctly powered 2x 1.2v Batteries are required
(You calculate using Minimum Source Voltage and Maximum Forward Voltage to ensure Diode is always adequately powered)

Lesson 2: Use a resistor
They saves blowing IR-LED's and prolongs the life of diode and battery. They only cost about 15 cents.
To calculate the required resistor you need the Maximum Source Voltage, Diode Typical Forward Voltage and Diode Forward Current. Smart people (not me) will use Ohm's Law, the rest just use an online calculator like http://led.linear1.org/1led.wiz.
Example:
Vishay 6400 Typical Forward Voltage = 1.35v
2x 1.2v Rechargeable AAA/AA Batteries = 2.4v
Diode Forward Current = 100ma
Put this data into the online calculator and you will get a 12ohm Resistor.
(You use the Maximum Source Voltage and the Typical Diode Forward Voltage to ensure Diode is adequately protected)

This is main data from Vishay's Datasheet for the TSAL6400 used to calculate the above. I have circled the necessary information. The Power Source data will need to come from its manufacturer too.

See below for full datasheet's

Lesson 3: IR LED's are polarity sensitive
The long connector (anode) is positive and the short connector (cathode) is negative. If you look carefully at the LED the cathode is the flat piece inside.

Lesson 4: Get a wide viewing angle IR-LED
I have tried a few 30 degree and a really strong 25 degree LED and all work best when directed into the wiimote, rather than the whiteboard as I intend to use it (thus not very good at angles). (Vishay 6400 seems to be the way).

Viewing angle graphs like this can usually be found on the IR-LED Datasheet (this is random example and not related to the IR-LED pics below)

Lesson 5: Use the correct IR-Led Wavelength
The filter at the front of the Wiimote filters certain wave lengths. The preffered wave length is 940nm. Some IR-Led's have lower wavelengths still in the Infrared Spectrum but are filtered by the wiimote. Thanks to  inio  for his knowledge, the theory is explained here:
http://www.wiimoteproject.com/ir-pens/what-is-the-wiimotes-preferred-peak-wavelength-t867.0.html

Lesson 6: Get a strong IR-LED
Having tried a few 20ma LED's have found too week at distance, 100ma is the ideal strength. (again Vishay 6400 seems to be the way).

Vishay Data Sheets

Lesson 7: How do I know my IR-LED works???
Easy look at it through your mobile phone camera (cool little trick). You will be able to see the importance of the viewing angle, with the 25 degree from the side it looks like a dim light in the distance, front on it is very bright. (Remember 25 degree's means 12.5 degree's either side of 0 degree's. Thus not very wide, even over a long distance)

These photo's are from a camera phone of a: 25 Degree viewing angle, 1.2v AAA, 12ohms Resistor, 100ma LED. Note you can "see" the light and how difficult it will be for an IR sensor to detect the light from angles greater than 35 degree's, but also how strong it is at 0 degree's.

LED @ 90 degree's

LED @ 20 degree's

LED @ 0 degree's

Lesson 8: Scematic
A basic IR-Pen scematic:

Lesson 9: Read all the instructions & feedback
I left this to last knowing most people like me won't even read the first lesson, until they get totally stuck or until they finally got it to work and then read the instructions to check they did it right!
benpaddlejonesIRPENmach1 failed because I only read the ingredients list (2x AAA batteries) but didn't read the complete instructions that said I should only use 1 of the 2 batteries!
benpaddlejonesIRPENmach2: failed because I reverse wired it and assumed it was a busted LED!
benpaddlejonesIRPENmach3: works (mostly thanks to the really smart dude at www.altronics.com.au) but only if it is directed at the wiimote because of its small viewing angle!
benpaddlejonesIRPENmach4: Works AWESOME see my video:http://www.wiimoteproject.com/videos/enhancing-teaching-learning-with-the-wiimote-interactive-whiteboard-t983.0.html

may your wiimote be with you!
 « : September 22, 2008, 11:05:54 PM benpaddlejones »

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 « #1 : May 06, 2008, 05:42:54 AM »

great knowledgebase

//UndCon

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 « #2 : May 08, 2008, 01:16:44 AM »

IR - LED Experiment

I have just ordered a range of Vishay & Osram IR LED's from 25-160 degree viewing angle.

I will run an experiemnt to see which gives the best performance.

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 « #3 : May 08, 2008, 12:13:40 PM »

Hey good tutorial.

What LED are you using in that picture?
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 « #4 : May 08, 2008, 07:45:52 PM »

What LED are you using in that picture?

25 Degree 100ma Viewing angle from Dick Smith Electronics (www.dse.com.au). A Australian electronics and components retail outlet. (similar to USA - Radioshack)

It doesn't work unless you point it directly at Wiimote ( no good for interactive white board).

I have just ordered a range of IR-LED's (from 25 degree VA to 160 degree VA) and I'm going to run an experiemnt to see which viewing angle works best, will post results.

 « : May 08, 2008, 07:50:04 PM benpaddlejones »

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 « #5 : May 24, 2008, 11:22:41 PM »

Added a new lesson on preffered wave lengths

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 « #6 : May 31, 2008, 04:38:41 PM »

Thanks for the excellent tutorial! One question though: what about the 'radiant intensity' of an IR led. Does that play any role in selecting the most suitable IR led?
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 « #7 : June 01, 2008, 02:35:27 AM »

What LED are you using in that picture?

25 Degree 100ma Viewing angle from Dick Smith Electronics (www.dse.com.au). A Australian electronics and components retail outlet. (similar to USA - Radioshack)

It doesn't work unless you point it directly at Wiimote ( no good for interactive white board).

I have just ordered a range of IR-LED's (from 25 degree VA to 160 degree VA) and I'm going to run an experiemnt to see which viewing angle works best, will post results.

Where are you getting the 160deg VA IR led from? DSE and Jaycar both do 25deg ones, and the waterclear ones from DealExtreme are 40ish deg.
Im going to try RS Components and Farnell on Monday.
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 « #8 : June 01, 2008, 04:36:36 AM »

Where are you getting the 160deg VA IR led from? DSE and Jaycar both do 25deg ones, and the waterclear ones from DealExtreme are 40ish deg.
Im going to try RS Components and Farnell on Monday.

Farnell
They are only 80deg (farnell's website was wrong) they don't work as well as Vishay TSAL6400.

I suggest go direct to Farnell and get Vishay TSAL6400 anything else doesn't work as well. (DSE, Jaycar and Altronics are useless).

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 « #9 : June 01, 2008, 04:55:24 AM »

Thanks for the excellent tutorial! One question though: what about the 'radiant intensity' of an IR led. Does that play any role in selecting the most suitable IR led?

I could be a little (or a lot) out of my depth but:

My understanding is Radient Intensity is a measure of light emmited over a period of time. Given the Wiimote locks for Blobs either at the IR-LED or reflected on the whitebaord this is not overlly relievent. It is also a function of the forward current so that is a suitable measure of strength for us nOOb's.

I welcome correction and advice from any Electronic/Physic Guru's though.

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 « #10 : June 01, 2008, 05:07:07 AM »

I am probably the uber-est n00b when it comes to this kind of electronics stuff so I'm not quite sure what to do. I thought I'd try out this wiimote whiteboard thing just to learn something and have a little fun at the same time I have bought some Vishay TSAL 6400 LED's so far... and I have no idea what to do. I did not buy resistors because I'm not sure what to get.

I understand that the LED's forward voltage is 1.35v and a max voltage of 1.6v? So if the voltage of a battery is 1.5v will it work without any resistors?

I'm sorry for asking what are probably some really stupid questions but I would love to get this working.
I appreciate anyone that takes the time to answer me
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 « #11 : June 01, 2008, 06:50:19 AM »

Kaos,

To know how to do a IR Pen go to my IR pens pages:
http://clinik.net/wiimote/wiimote_info_my_pen_1.php
http://clinik.net/wiimote/wiimote_info_my_pen_2.php

I use a 1.35v - 1.6v led with a 1,5v battery with good results!!!

Cheers!

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 « #12 : June 01, 2008, 07:18:18 AM »

Looks like its farnell after all, might have to order 25 or 50 of them to make the shipping worthwhile.

Either that or wait until the electronics guys at work order something from them.
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 « #13 : June 01, 2008, 06:03:03 PM »

Thanks for the excellent tutorial! One question though: what about the 'radiant intensity' of an IR led. Does that play any role in selecting the most suitable IR led?

I could be a little (or a lot) out of my depth but:

My understanding is Radient Intensity is a measure of light emmited over a period of time. Given the Wiimote locks for Blobs either at the IR-LED or reflected on the whitebaord this is not overlly relievent. It is also a function of the forward current so that is a suitable measure of strength for us nOOb's.

I welcome correction and advice from any Electronic/Physic Guru's though.

See http://www.vishay.com/docs/49495/sg2123.pdf
I see that the wider the angle the lower the radient intensity. The difference between the 5300 and the 6400 reveals that the 5300 will be brighter as is mentioned somewhere in this forum.
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 « #14 : June 01, 2008, 06:55:38 PM »

apdewith and all,

http://www.wiimoteproject.com/ir-pens/inside-my-ir-pen-t929.0.html

"Can we say that TSAL 5300 is better than TSAL 6400?
Have we a 'new' winning IR led?"

I have two pens:

TSUS 5400
(IR Pen #1 - with red end)

Peak Wavelength: 950
Angle of Half: 22
Rise and Fall: 14

TSAL 5300
(IR Pen #2 - with black end)

Peak Wavelength: 940
Angle of Half: 22
Rise and Fall: 45

I post here a photo (made by Macbook Pro webam...) of both
@ 90 degree's and @ 45 degree's.
The 45 degree's photo shows very clearly which its brighter!!!