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Old 11-22-2012, 09:27 AM   #1
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Default Fun With LEDS

Hey guys,

Does anyone on here dabble with LEDs? I certainly don't but i'd love to!

I have done 1 project previously which was as basic as you can get but i'm genuinely interest to learn more.

I've looks about and you can get like 100 White 12V LEDs for 10 which isn't bad and I can think of a lot of things I could add LEDs to

First off where do resistors come into it?
My 1 and only project was a battery pack and 15 LEDs, meaning 15 wires going from the battery pack to each LED as apposed to running them in a serious with the right resistors?

Next off Patters / Controls
Is it easy (easy being an optimistic word) is it plausibly manageable to create a series of something very small say 10 LEDs and then have a way so that 1st LED comes on then off, then the 2nd then the 3rd etc so you have "chase" type effect?
How do you go about this?

Genuinely interested in this and it would be nice if there was someone here with some experience.
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Old 11-22-2012, 10:00 AM   #2
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Default Re: Fun With LEDS

Hi ssc456

Little bit on LEDs/Modding > Kustom PCs LEDs
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Old 11-22-2012, 10:23 AM   #3
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Default Re: Fun With LEDS

LED's are current sensitive. Over drive them and they burn out. Some will even explode like a popcorn kernel.
Parallel
Wiring up multiple LEDs in parallel

Series
Wiring up multiple LEDs in series

Sequencer
Images 1
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Old 11-22-2012, 11:12 AM   #4
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Default Re: Fun With LEDS

Thanks Guys,

Looks like that Sequencer is going to be a little more complicated than I first thought.
I'm going to have a Google to see if there are any USB LED Sequencers.
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Old 11-28-2012, 05:28 PM   #5
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Default Re: Fun With LEDS

Usually those 5mm resistors work without resistors at 5V. If you hooked it up to a 12V circuit with no resistor the LED would almost immediately die.

I do one project with LEDs for car radio adapters (on the HVAC controls).




There's lots of projects you can do with LEDs.
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Old 11-28-2012, 06:21 PM   #6
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Default Re: Fun With LEDS

I've done a fair bit of basic electronics stuff, including various bits with LEDs - they're just another basic electronic component in my book! I tend to accumulate them over time (look out for the cheap as chips ones from China on ebay, you can get them very cheaply here.)

Have I got any lying around? Of course, who doesn't!



Various sorts there - clock displays, 7 segment displays of varying colours (though none of the boring old red ones!) normal 3mm indication ones (those really are cheap as chips), 5mm ones of various colours (along the back), super bright ones (bottom left in the individual packets, one of those suckers almost blinded me when I first switched it one unwittingly), and thru-hole rgb ones (the ones towards the centre with four pins.) I have others around in various places, those were just the ones I could get my hands on quickly, the others are behind my much bigger box of resistors and ICs which I couldn't be bothered to dig out But that should give you an overall selection of the most common sorts of things available.

Firstly, resistors come into it because an LED's current draw isn't linear - it's resistance decreases as more current is passed through it, so more current passes through, so the resistance decreases, so more current passes through - until either the LED blows, the curve flattens off or the power source can't supply more current. To make sure we *know* what happens, we generally put a resistor in series with the LED to make sure there's a constant resistance there, keeping a check on the current draw and making sure the LED doesn't blow. (You can work out the value of this resistor by looking at the LED's data sheet, but for most around 330Ohms is fine.)

Each LED should really have its own current limiting resistor in order to a) not overload the resistor if you're using large numbers of higher powered LEDs and b) not screw up the whole circuit if just one component fails. It's also considered good practice.

In terms of chasing the lights, there's several ways you could do this. Possibly the simplest would be to use a 555 timer - they're a passive component so no programming involved, cheap as chips, and you specify the timing rate by putting an appropriate capacitance value between a couple of the pins (again, you can work this out by the datasheet.)

If you want to get more complicated than flashing - say fading, or something like that - you can look at a microcontroller. Perhaps the simplest way to get started with these is with an Arduino - tons of stuff around on the web, cheap (around 10 for an Arduino Uno) and very easy to use. If it were me I'd probably knock up something on an Arduino first then transfer it to an ATTiny and use that (standalone, very cheap tiny chip.)

In fact, you've got me inspired. If I get any time between now and Christmas (doubtful but possible!) I may just see if I can create a few Christmas decorations... :-)
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Old 11-29-2012, 05:00 PM   #7
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Default Re: Fun With LEDS

Quote:
Originally Posted by berry120 View Post
I've done a fair bit of basic electronics stuff, including various bits with LEDs - they're just another basic electronic component in my book! I tend to accumulate them over time (look out for the cheap as chips ones from China on ebay, you can get them very cheaply here.)

Have I got any lying around? Of course, who doesn't!



Various sorts there - clock displays, 7 segment displays of varying colours (though none of the boring old red ones!) normal 3mm indication ones (those really are cheap as chips), 5mm ones of various colours (along the back), super bright ones (bottom left in the individual packets, one of those suckers almost blinded me when I first switched it one unwittingly), and thru-hole rgb ones (the ones towards the centre with four pins.) I have others around in various places, those were just the ones I could get my hands on quickly, the others are behind my much bigger box of resistors and ICs which I couldn't be bothered to dig out But that should give you an overall selection of the most common sorts of things available.

Firstly, resistors come into it because an LED's current draw isn't linear - it's resistance decreases as more current is passed through it, so more current passes through, so the resistance decreases, so more current passes through - until either the LED blows, the curve flattens off or the power source can't supply more current. To make sure we *know* what happens, we generally put a resistor in series with the LED to make sure there's a constant resistance there, keeping a check on the current draw and making sure the LED doesn't blow. (You can work out the value of this resistor by looking at the LED's data sheet, but for most around 330Ohms is fine.)

Each LED should really have its own current limiting resistor in order to a) not overload the resistor if you're using large numbers of higher powered LEDs and b) not screw up the whole circuit if just one component fails. It's also considered good practice.

In terms of chasing the lights, there's several ways you could do this. Possibly the simplest would be to use a 555 timer - they're a passive component so no programming involved, cheap as chips, and you specify the timing rate by putting an appropriate capacitance value between a couple of the pins (again, you can work this out by the datasheet.)

If you want to get more complicated than flashing - say fading, or something like that - you can look at a microcontroller. Perhaps the simplest way to get started with these is with an Arduino - tons of stuff around on the web, cheap (around 10 for an Arduino Uno) and very easy to use. If it were me I'd probably knock up something on an Arduino first then transfer it to an ATTiny and use that (standalone, very cheap tiny chip.)

In fact, you've got me inspired. If I get any time between now and Christmas (doubtful but possible!) I may just see if I can create a few Christmas decorations... :-)
I don't -- can you send me some of those??!!
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Old 11-29-2012, 06:19 PM   #8
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Quote:
I don't -- can you send me some of those??!!
In all seriousness, browse around the chinese sellers on ebay. I've had 100 or so 5mm LEDs in assorted colours sent to me including postage for less than 1!
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Old 11-29-2012, 06:33 PM   #9
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In all seriousness, browse around the chinese sellers on ebay. I've had 100 or so 5mm LEDs in assorted colours sent to me including postage for less than 1!
Wow, can you PM me some links?
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Old 11-29-2012, 06:56 PM   #10
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Originally Posted by szvwxcszxc View Post
Wow, can you PM me some links?
The offers come and go quite quickly (it's probably a case of whatever surplus LEDs and other assorted bits they've got lying around at that particular moment.)

100 red ones (5mm) for 1.38 currently here though: 100Pcs LED 5MM RED COLOR RED LIGHT Super Bright Bulb Lamp | eBay

Trick is to search in the "electrical and test equipment" category, and make sure you tick worldwide to get the bulk of the chinese ones. Shipping takes a while, sometimes up to a month - but for that price I'm happy stocking up so I've just got them when I need them.
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