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FreeTrack Forum > FreeTrack : English Forum > Support : Tracking System > Using the LED setup wizard

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RSS >  Using the LED setup wizard, entering values
TheFabFour #1 09/09/2010 - 19h02

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when entering the values of the 'LED' into the wizard, (3 led clip on type) do I add up the values of the three LED's?  One LED being 1.2 volts / 100ma

So should I enter 3.6 volts and 300ma into the wizard to get it to calculate the correct resistor?

I am going to use an old radio shack power supply of 12 Volts.

TheFabFour
TheFabFour
FALL3N #2 10/09/2010 - 18h21

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just put in the value for one led. and put the dot into the 3 clip or cap position. And example of what I have done is as follows.

everything from radio shack.

IR LED Part# - 276-0143 (3 items)
Soldering flux
SPST-Submini Slide Switch part# - 275-0406 (used only one but 2 come in the pack)
Resistors will depend on the outcome of the power supply. So for what you have as a power supply his is what you will need with the Radio Shack IR LED part# 276-0143

you will need 120 Ohm Resistor 3 LEDs and wire this in series as that is what the calculator calls for. Honestly though you could just get the 9v batter clips from Radio shack and just use 2 9V batteries this would give you 18 Volts and Radio shack has 150 Ohm Resistors for this. I honestly wouldnt use a unregulated power supply as you could get a decreasing or increasing power spike in your house and blow/shorten the life of the resistor and LEDs. If you need any more help dont hesitate to post.
Edited by FALL3N on 10/09/2010 at 18h22.
dewey1 #3 11/09/2010 - 00h19

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Using two 9 volt batteries in series is absolutely ridiculous! Why?
Your just wasting battery power for no reason.
A 9 volt battery will not last very long compared to 4 AA in series for 6 volts.

You can get 10 of the SFH485P leds from Digi-Key for the same price you pay for the three from Radio Shack. No filing of led lens to get wider angle either.

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SpecterM #4 11/09/2010 - 01h59

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its true.  Have patience and do it right.  it will cost more in the long run if  you try doing this quickly.
Join the -=UGF=- Teamspeak, I'm here to help.  IP: 76.73.228.80 Port: 9987
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TheFabFour #5 11/09/2010 - 17h30

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Thanks for all the info.  I've been using a free track for about a year now that I built myself.  It seemed to go through the AA batteries in just a few hrs.  Then I added the unregulated power supply and I have not had a problem with it yet.

I plan on building a few more with the LED's that have the flat front. (thanks for the tip) I had a problem with the resistors and resorted to trial and error to get it to work.  That's why my original question about how to use the LED setup wizard.

I like the plug in power supply as it adds little weight to the clip and since I have a wire hanging from the head set anyway one more wire is no problem and no batteries to worry about going dead.

Also, thanks for the diagram showing the placement of the resistors, should be very helpful.

TheFabFour
TheFabFour
TheFabFour #6 11/09/2010 - 17h55

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Okay I ran the setup wizard and it tells me I need one 120 ohm resistor.

I went to Radio Shack and the guy helping me knows less than me and I know nothing!!

I found a resistor that is 120K ohm.  Is that what I'm looking for?  This stuff is very confusing for a lay person.  This is the reason that I had to do the trial and error on my first build.  If I can't find the 120 ohm resistor can I use a combination of several resistors to add up to that value?  I'm so confused.

TheFabFour
TheFabFour
dewey1 #7 11/09/2010 - 20h19

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No, 120K is equal to 120,000 ohms.

You may find 150 ohm 5% 1/2w. (BRN-GRN-BRN-GLD)

http://www.radioshack.com/product/index.jsp?productId=2062316&numProdsPerPage=60&retainProdsInSession=1

This will give about 56ma of current.

Otherwise a 100 ohm and 22 ohm in series will give 122 ohm.

100 ohm 5% 1/2w (BRN-BLK-BRN-GLD)
http://www.radioshack.com/product/index.jsp?productId=2062315&numProdsPerPage=60&retainProdsInSession=1

22 ohm 5% 1/2w (RED-RED-BLK-GLD)
http://www.radioshack.com/product/index.jsp?productId=2062311&numProdsPerPage=60&retainProdsInSession=1
Edited by dewey1 on 11/09/2010 at 21h11.
TheFabFour #8 11/09/2010 - 23h03

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lol, thanks for the info.  I will try to order the resistors in.  The store has a limited selection.  I've been told that Radio Shack is going to phase out the in store electronics items such as these.

Thanks so much for the help.


TheFabFour

Don't I need 100ma of current to run the three LED's?
Edited by TheFabFour on 11/09/2010 at 23h06.
TheFabFour
dewey1 #9 12/09/2010 - 00h30

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No, you never want to operate electronic components at maximum.

50ma to 75ma is more than enough.

Radio Shack has been downsizing for over 20 years.
Where do you live in the states?

Reason I ask is because of possible shipping costs for ordering from Digi-Key.
They are alot cheaper than Radio Shack.
FALL3N #10 13/09/2010 - 00h36

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well dewey the reason I went with what I have is because Radio shack doesnt have the exact resistors I would need for a 4aa battery layout in series. Also I did find one resistor to work with the 4aa series setup but the power output wasnt strong enough to power the 2nd and 3rd leds. This is why I went with 2 9v batteries as 2 9v batteries are cheaper than 4 aa batteries (4.99 USD for 4aa's comapaired to 2.99 USD for 2 9v).

So in essence to say it is a waist is absolutly wrong. and the 2 9v's will last longer than 4 aa's will anyway. I know because I have tested it wth several different circuit setups for several different devices. Also the circuit calulator isnt completely right with all the mirad of circuit layouts that can be achived (I.E. series-paralell, Series W/ capasitor, Paralell w/ ICS...ETC ETC). It will give however the best basic setup you might want to try. But for IR-LEDs that push 1.2 V FFV and 100mA FC the calculator isnt correct with the resistor it recommends as the 33 Ohm Resistor blocks way to much voltage to 2 LED's let alone 3.
dewey1 #11 13/09/2010 - 19h14

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FALL3N @ 13/09/2010 - 00h36 a dit:

well dewey the reason I went with what I have is because Radio shack doesnt have the exact resistors I would need for a 4aa battery layout in series. Also I did find one resistor to work with the 4aa series setup but the power output wasnt strong enough to power the 2nd and 3rd leds.
What value was that resistor and what leds are  you using.
This is why I went with 2 9v batteries as 2 9v batteries are cheaper than 4 aa batteries (4.99 USD for 4aa's comapaired to 2.99 USD for 2 9v.

At Walgreens, Duracell Coppertop, two 9v batteries and four AA are the same price!
That is 3 USD.
So in essence to say it is a waist is absolutly wrong. and the 2 9v's will last longer than 4 aa's will anyway. I know because I have tested it wth several different circuit setups for several different devices.

Well that is going to vary depending on the "different circuit setups."
The best method overall is to use a constant current regulator.
Also the circuit calulator isnt completely right with all the mirad of circuit layouts that can be achived (I.E. series-paralell, Series W/ capasitor, Paralell w/ ICS...ETC ETC). It will give however the best basic setup you might want to try. But for IR-LEDs that push 1.2 V FFV and 100mA FC the calculator isnt correct with the resistor it recommends as the 33 Ohm Resistor blocks way to much voltage to 2 LED's let alone 3.

After 45 years in the Electronics field, I do not have to use a "circuit calculator".
I have been known to use a pencil and paper, possibly a slide rule, and now a days maybe a calculator. Sometimes I just do it in my head.


Here is a bit of information gathered to inform some people.
The formula is Battery Life = Battery Ampacity (mA) / Current Draw (mA)

With 50mA constant current load we yield the following results:

Assume 50% for "actual real life" verses calculated. .8 volts per cell is end of life. ( 9 volt battery is 4.8v)  (6 volt battery is 3.2v)

        Typical Average                               Duracell spec            Duracell  at 50%        Walgreens Drug for prices       Cost per Hour

(1) 9 Volt battery (565mAh / 50mA = 11.3 hours)    550mAh $1.50    About 5.5 hours actual    1x Reference    $1.50    $.27 per hr

(4) AAA batteries (1190mAh /50mA =  23.8 hours) 1000mAh $.75    About 10 hours actual    1.8x longer    $3.00    $.30 per hr

(4) AA batteries (2707mAh / 50mA =  54.1hours)    2100mAh    $.75    About 21 hours actual    3.8 longer    $3.00    $.14 per hr

(4) C batteries (7935mAh / 50mA =  158.7 hours)    7000mAh $1.50    About 70 hours actual    12.7x longer    $6.00    $.09 per hr

(4) D batteries (17,100mAh / 50mA =  342 hours)    14000mAh $1.50    About 140 hours actual     25.4x longer    $6.00    $.04 per hr

Since most people do not use a constant current circuit for their IR emitter clips or hats the actual life time will be longer. In other word they are using a fixed resistor value.
For a given resistor value the current will decrease as the cell voltage decreases. A 1.5 volt cell will be 1.5 volts for the first 10% of it life expectancy.
TheFabFour #12 13/09/2010 - 21h44

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I ordered the IR LED's (10 pack) From Digi-Key, but after the shipping cost it came to $15.20.  At least I will get the IR LED's that are flat on the tip.  So all in all not bad.

thefabfour
TheFabFour
dewey1 #13 13/09/2010 - 22h10

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TheFabFour @ 13/09/2010 - 21h44 a dit:

I ordered the IR LED's (10 pack) From Digi-Key, but after the shipping cost it came to $15.20.  At least I will get the IR LED's that are flat on the tip.  So all in all not bad.

thefabfour



Wow that is a lot for shipping. I hope you went with standard mail rather than other shipping methods.
Where do you live that it was that much?

From Minnesota to Wisconsin, I paid around $6 for 10 pcs and that included shipping
and I got them in 2 days. The led price was $.44 each in 10 quantity.

You will be happy using them. No filing or modifying. Plus you have some extra!
Even at $1.52 each, that is better than $2 each from the Shack.
ShiMaKe #14 14/09/2010 - 06h57

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Here's a poser, I live in a backassward country. They only sell IR leds without any specs whatsoever. Sort of generic IR led. Even a local electronics guy told me none of the few diy electronics shops will tell you the specs, even if they know.

My question is, would the best guess be the same specs for the Radio Shack IR led 276-143? There don't seem to be many different kinds of IR leds out there AFIK

Thanks guys


BTW any shipping here would be many times more than the cost of the leds themselves.
dewey1 #15 14/09/2010 - 19h59

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ShiMaKe @ 14/09/2010 - 06h57 a dit:

Here's a poser, I live in a backassward country. They only sell IR leds without any specs whatsoever. Sort of generic IR led. Even a local electronics guy told me none of the few diy electronics shops will tell you the specs, even if they know.

BTW any shipping here would be many times more than the cost of the leds themselves.



I do not not know where "backassward country" is located!  :D

At least tell us what country! We may be able to help with a source!
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