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Author Topic: LED HELP!!!  (Read 3961 times)

Mark47

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LED HELP!!!
« on: March 13, 2009, 04:53:50 PM »

Well I have read about 20 articles today to try and understand this form of lighting and my heads about to go BOOM %% %% %%

I plan to run my LEDs of off 6volts. I need some help to place an order for some of these tiny wee  :-X I think I'm suffering from info overload O0. I want to put them in my Trent Lifeboat. I am looking at working mast, deck, navigation and some interior lighting (interior done through fiber optics). So I will need 2x Green, 2x Red, 1x yellow, 1x flashing blue, 15x white all in 3mm. I will also need 21 x voltage suppressors (diodes, I think I need different ones for different coloured bulbs)?

Can anyone help me out here?

Many thanks to anyone who can help compile my order...........should have just stuck to grain of rice bulbs O0 but don't want to try and leave access to them all for replacing.

Mark
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Umi_Ryuzuki

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Re: LED HELP!!!
« Reply #1 on: March 13, 2009, 05:50:47 PM »

LED, are Diodes.  Light Emitting Diodes.

You need Resistors.  ok2

This should help with resistors.
http://led.linear1.org/1led.wiz


Do not hook up any LED without the
resistors in place.

Yellow and red
Forward Voltage 1.8v-2.2v
Forward Current 18 mA

White and Green
Forward Voltage 3.2-3.4v
Forward Current 20mA

Source voltage will be the battery or
the power supply voltage.

_______________________________________

LED Resisitors for 6v
Yellow/Red    220ohm 1/8watt
White/Green   150ohm 1/8watt

LED Resisitors for 12v
Yellow/Red    560ohm 1/2watt
White/Green   470ohm 1/2watt

 :-))


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Mark47

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Re: LED HELP!!!
« Reply #2 on: March 13, 2009, 05:57:20 PM »

LED, are Diodes.  Light Emitting Diodes.

You need Resistors.  ok2



Told you I have not got a clue :embarrassed: :embarrassed: :embarrassed:

Mark
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Mark47

  • Guest
Re: LED HELP!!!
« Reply #3 on: March 13, 2009, 06:08:35 PM »

LED, are Diodes.  Light Emitting Diodes.

You need Resistors.  ok2

This should help with resistors.
http://led.linear1.org/1led.wiz


Do not hook up any LED without the
resistors in place.

Yellow and red
Forward Voltage 1.8v-2.2v
Forward Current 18 mA

White and Green
Forward Voltage 3.2-3.4v
Forward Current 20mA

Source voltage will be the battery or
the power supply voltage.

_______________________________________

LED Resisitors for 6v
Yellow/Red    220ohm 1/8watt
White/Green   150ohm 1/8watt

LED Resisitors for 12v
Yellow/Red    560ohm 1/2watt
White/Green   470ohm 1/2watt

 :-))




Would it be better to run these in parallel with separate resistors???

Mark
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craftysod

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Re: LED HELP!!!
« Reply #4 on: March 13, 2009, 07:01:26 PM »

From one Mark to another Mark,we are gaining on the forum.
This link might help
http://www.maplin.co.uk/Search.aspx?criteria=12v%20led&source=15
Mark
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Mark47

  • Guest
Re: LED HELP!!!
« Reply #5 on: March 13, 2009, 07:21:29 PM »

I now know what quantities of 1/8watt resistors I'm looking for, I know the ohm numbers I'm looking for (100,150,270), I also know what colour banding they should have.

But all the web sites list things like 0.25w and "The kit contains the following values:10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68 and 82Ωplus all decade values up to 1MΩ" So my next question is. What the h*ll does that mean??????????????. As you can tell I'm starting to loose patience with this idea. I could have been building for the last few hours. >>:-(
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The long Build

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Re: LED HELP!!!
« Reply #6 on: March 13, 2009, 07:31:02 PM »


You need Resistors.  ok2


Do not hook up any LED without the
resistors in place.



Am thinking of using some as well, so why do we need resistors ?
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Umi_Ryuzuki

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Re: LED HELP!!!
« Reply #7 on: March 13, 2009, 07:33:13 PM »

I typically run mine in parallel with separate resistors.

However, for lots of LED, it can be simpler to run them in series till the
number of LED, in volts, matches the voltage of your battery.

So, 7 serial wired pairs of white LED run in parallel

If you wanted to wire all  15 of the white LED in parallel, and add one resistor
to the head of the line, you would likely need an 2.0 watt resistor to handle
the current. Maybe go with a 5 watt just to give it some allowance.


______________

The resistors help the match the voltage 3v, 6v, 9v, 12v, of the battery to the voltage limits of the LED

The Ohms is the resistance.  You need ohms to reduce the voltage from 6v to 1.8 - 3.4 volts for the LED.
If the resistance, ohms, is too small, you will burn out the LED,... too much voltage.
If the resistance. ohms, is too large, the LED will not get enough volts, and refuse to light up.

The watts is the current. The resistors can only handle a certain amount of current. If the LED or set of LED
draws more current, watts, than the resistor can handle, then the resistor will burn out.

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Mark47

  • Guest
Re: LED HELP!!!
« Reply #8 on: March 13, 2009, 07:51:07 PM »

I typically run mine in parallel with separate resistors.

However, for lots of LED, it can be simpler to run them in series till the
number of LED, in volts, matches the voltage of your battery.

So, 7 serial wired pairs of white LED run in parallel

If you wanted to wire all  15 of the white LED in parallel, and add one resistor
to the head of the line, you would likely need an 2.0 watt resistor to handle
the current. Maybe go with a 5 watt just to give it some allowance.


______________

The resistors help the match the voltage 3v, 6v, 9v, 12v, of the battery to the voltage limits of the LED

The Ohms is the resistance.  You need ohms to reduce the voltage from 6v to 1.8 - 3.4 volts for the LED.
If the resistance, ohms, is too small, you will burn out the LED,... too much voltage.
If the resistance. ohms, is too large, the LED will not get enough volts, and refuse to light up.

The watts is the current. The resistors can only handle a certain amount of current. If the LED or set of LED
draws more current, watts, than the resistor can handle, then the resistor will burn out.



I do get what you have said. :-))

I don't mind running them all with seperate resistors, I would probably feel happier doing so. But what does this mean in english "values:10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68 and 82Ωplus all decade values up to 1MΩ" I presume this is 10ohm, 12ohm,15ohm and so on, or I am I way off track here?
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craftysod

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Re: LED HELP!!!
« Reply #9 on: March 13, 2009, 07:54:04 PM »

Yes that is ohms
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malcolmfrary

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Re: LED HELP!!!
« Reply #10 on: March 13, 2009, 08:04:01 PM »

Quote
Am thinking of using some as well, so why do we need resistors ?
Left to its own devices, an LED will pass infinite current.  It will dissipate the power from this, which will be considerable, and will let you know that it is unhappy by emitting what us technical blokes call "A heck of a flash" during which it will die.  The purpose of the resistor in series is to limit the current to a level that the LED can survive.  Some LEDs have a resistor built in, and cost accordingly.
Quote
But what does this mean in english "values:10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68 and 82Ωplus all decade values up to 1MΩ" I presume this is 10ohm, 12ohm,15ohm and so on, or I am I way off track here?
This sounds like you are looking at a boxed set of hundreds and hundreds of resistors of pretty much all known values, suitable for a class of students to play with.  Avoid like the plague.  Once you have decided what values you want, and how many, ask for them at the counter.  You have no need for all the other values.
You may well have decided that 1/8 watt resistors are the thing.  It will do no harm to use 1/4 watt - in many cases they are the same-ish price and are marginally larger.
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"With the right tool, you can break anything" - Garfield

Mark47

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Re: LED HELP!!!
« Reply #11 on: March 13, 2009, 08:20:54 PM »

Thank you everyone who has taken the time to reply. :-)) :-)) :-)) :-)) :-)) :-)) :-))

Believe it or not I actualy think I know what I'm doing and ordering O0 O0 O0, just need to find a site that won't charge a 5 delivery for a 6 order ;) {-) {-) {-).

then I can get back to beer :D. Oops did I type that :}, I ment build O0.

Mark
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craftysod

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Re: LED HELP!!!
« Reply #12 on: March 13, 2009, 08:40:15 PM »

Mark
Build+Beer+Bulbs=happiness
Mark
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Mark47

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Re: LED HELP!!!
« Reply #13 on: March 13, 2009, 08:42:07 PM »

Mark
Build+Beer+Bulbs=happiness
Mark

 {-) {-) {-) {-) {-) {-) {-)
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Rex Hunt

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Re: LED HELP!!!
« Reply #14 on: March 13, 2009, 09:48:44 PM »

You may find this site helpful too

http://led.linear1.org/led.wiz

It will tell you how to link up 'arrays' of LEDs in series and parallel combinations,work out the right resistor values and give you the colour coded bands that mark their value.


Good gen.

When buying resistors play safe.......if you think a 1/8 Watt one will do....... fit a 1/4 watt one to be on the safe side!

Rex
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Mark47

  • Guest
Re: LED HELP!!!
« Reply #15 on: March 13, 2009, 10:56:58 PM »

You may find this site helpful too

http://led.linear1.org/led.wiz

It will tell you how to link up 'arrays' of LEDs in series and parallel combinations,work out the right resistor values and give you the colour coded bands that mark their value.


Good gen.

When buying resistors play safe.......if you think a 1/8 Watt one will do....... fit a 1/4 watt one to be on the safe side!

Rex

Umi_Ryuzuki beat you to it, but yes it's a cracking site. :-)) :-))
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OMK

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Re: LED HELP!!!
« Reply #16 on: March 14, 2009, 12:56:02 AM »

But what does this mean in english "values:10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68 and 82Ωplus all decade values up to 1MΩ" I presume this is 10ohm, 12ohm,15ohm and so on, or I am I way off track here?

No, you are spot on. Those numbers are indeed resistance values, and that particular series of values are known as the E12 series range. E12 values have a tolerance value of plus/minus 5 percent...... perfect for LEDs.
As to the 'decade' thing, all you need do is stick a '0' (zero) on the end of each number. 10 ohms then becomes 100 ohms; 12 ohms then becomes 120 ohms, etc, etc. Stick another '0' on the end and 100 ohm then becomes 1,000 ohms; 120 ohms then becomes 1,200 ohms...... and so on.

Incidentally, since your battery is just 6v, then a 1/8watt series resistor on each LED is plenty man enough. Also, 1/8w res's are physically smaller than, say, 1/4w res's, which means when it's soldered to the LED and covered in heatshrink you'll hardly notice it there.

<edit>

By the way, why are you looking at whole packs of resistors anyway? That's an expensive way of doing it - especially when you end up with a zillion resistors that you will probably never need. Do you know that you can buy individual resistors for just 0.002 each?
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Mark47

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Re: LED HELP!!!
« Reply #17 on: March 14, 2009, 03:25:12 AM »

By the way, why are you looking at whole packs of resistors anyway? That's an expensive way of doing it - especially when you end up with a zillion resistors that you will probably never need. Do you know that you can buy individual resistors for just 0.002 each?

I only looked at the pack because some of the sites I had been on did not list the size of resistor I need. I think I'm going to have to bite the bullet and order from Rapid and pay 5 postage for a 6-7 order (well there prices compaired to some it's more like 10-11). They are the only site with everything in stock.


Mark
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towboatjoe

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    • Towboat Joe
Re: LED HELP!!!
« Reply #18 on: March 14, 2009, 04:53:01 AM »

Why do people make everything so complicated?
I've never used resistors.
I just wire all my LED's series/ parallel to two 1.5 v. batteries with a switch and leave it go at that.
I've got some that have been burning since 1992.
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OMK

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Re: LED HELP!!!
« Reply #19 on: March 14, 2009, 06:04:52 AM »

Agree what you say about Rapid. But I was thinking maybe you could try www.esr.co.uk (2.50 shipping, no minimum order). I'm not certain they will stock everything on your list, but they are guaranteed good for resistors. Watch out for the VAT.

On the other hand, maybe towboatjoe has a point........ And the money you save on rip-off shipping fees could instead be spent on a bunch of 1.5v rechargable's and battery holders (with maybe enough left over for a swanky radio-controlled-switch for turning all them LEDs on and off from your transmitter).
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Mark47

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Re: LED HELP!!!
« Reply #20 on: March 14, 2009, 10:57:53 AM »

By the way, why are you looking at whole packs of resistors anyway? That's an expensive way of doing it - especially when you end up with a zillion resistors that you will probably never need. Do you know that you can buy individual resistors for just 0.002 each?

I only looked at the pack because some of the sites I had been on did not list the size of resistor I need. I think I'm going to have to bite the bullet and order from Rapid and pay 5 postage for a 6-7 order (well there prices compaired to some it's more like 10-11). They are the only site with everything in stock.


Mark

Well bit the bullet and ordered 2x red led, 1x yellow led, 2x green led, 1x blue flashing led, 3x packs of 100 resistors (did not sell what I need in singles), total price 2.05. not to bad, but with vat and delivery 8.06 >>:-(. Not a very cost effective way. So went to Ebay for white super bright leds x 50 5 with free postage. Ordered 6 metres of 3mm heat shrink 2.50 from another E bay source (more than I need, but always handy for other jobs). O0


As you can see My total order spread over three companies was  17.61 (I did not factor in the heat shrink in my initial costs, but to get it all at Rapid I was looking at a price nearer 25 and that was for only the 15 white leds I needed. Not the 50 I have ordered. It pays to shop around O0 O0 O0 O0. I'll just have to wait for three deliveries now. {:-{ {:-{


Mark
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Mark47

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Re: LED HELP!!!
« Reply #21 on: March 14, 2009, 03:41:43 PM »

EDIT FOR ABOVE POST- The £25 price at Rapid does include 50 bulbs, but only standard See what happens when you stay up all night trying to find LEDs

Mark
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