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Led's - Series Or Parallel?


MonkeyMark
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Got a couple of projects planned using the 5050 style led's.

 

How does it affect them wiring series or parallel when cut into short strips?

Just beginning our adventure. 95% of my time on CT I use my phone. As a result correct spelling and grammer will be used sparingly. This is due to fat fingers. Please don't let it bother you.

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You must be brave to use surface mount LED's not had much luck soldering surface mount. However as with most LED's it is the current which is important as to if building a current regulator or relying on a resistor is another thing I did a whole lot of experiments including over driving and pulsing the input but that was with smaller LED's and from what I am told heat is a real problem with these LED's so really do need a heat sink. So step one is clearly to design the printed circuit board with this in mind.

 

Colour does change the voltage I know red LED's had about 1. 2 volt drop across them and I used this to lift the output of a 7812 voltage regulator to 13. 2 volt by putting LED between device com and real com work like a zenor diode.

 

Assuming running off 12 volt which will likely range 12 to 13. 8 the more LED's in series using a simple resistor as current limit the dimmer they will get when the voltage drops so calculate on 5 then use 6 in series will mean one can go short circuit without blowing the rest and so bright likely good enough.

 

However my friend found some small switch mode power supply chips and clearly this really reduces the heat. I seem to remember him saying he had to buy 100 at a time so was selling the surplice at the local radio club.

 

The LED's can be bought already mounted on a flexible printed circuit with resistance already installed the 5050 refers to size of the package personally I would want to buy ready soldered onto a printed circuit in which case one has little control as to series of parallel.

 

Once talking about a pre-wired printed circuit it depends how that printed circuit is wired. "gumdrop" is lucky living in Bristol from memory three ham radio shops all selling books and staffed by cleaver guys who will help but as to Co. Durham not a clue what is local there?

 

I would go by the idea the LED is around 1. 2 volt may be 2 volt but around that area and with the examples I could find pre-fixed on printed circuit you could read the resistor size so should be able knowing the wattage to work out if a resistor each or common resistor for so many lights.

Edited by ericmark
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I think MM was talking about when he's cut the strips of 3 up, you need to put them in parallel i. e. all the +'s together and all of the -'s together.

 

J

Yes John, that is what I meant.

 

On one project they will be in a sort of star formation similar to one of the pics in your thread.

As it will be limited for space im trying to work out the best way to chain them together without crossing.

If they are side by side could you start with + then link it's - to the + of the next so the final - links back to power supply?

 

Sort of daisy chaining them to keep connecting wires to a minimum.

 

How did you do yours John?

Just beginning our adventure. 95% of my time on CT I use my phone. As a result correct spelling and grammer will be used sparingly. This is due to fat fingers. Please don't let it bother you.

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Yes John, that is what I meant.

 

On one project they will be in a sort of star formation similar to one of the pics in your thread.

As it will be limited for space im trying to work out the best way to chain them together without crossing.

If they are side by side could you start with + then link it's - to the + of the next so the final - links back to power supply?

 

Sort of daisy chaining them to keep connecting wires to a minimum.

 

How did you do yours John?

 

The easy way with a star or circular type formation like I did is to do the negative on the outside edge and the positive on the inside edge, there are solder pads at each end of the cut strips.

J

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The easy way with a star or circular type formation like I did is to do the negative on the outside edge and the positive on the inside edge, there are solder pads at each end of the cut strips.

J

Good point John. For some reason I'm trying to over complicate things.

 

One project will be running from a 9v battery so I'll have to work out how long it will last as I believe parallel draws more power.

 

Where do you buy your bare tinned copper from john? Checked eBay and can only find insulated so would need stripping.

Just beginning our adventure. 95% of my time on CT I use my phone. As a result correct spelling and grammer will be used sparingly. This is due to fat fingers. Please don't let it bother you.

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Parallel cos in series and they will become dim as the voltage is spread across the strips. Still arrange them in a pattern but make sure the +ve 12V goes to the +ve end of each LED strip and the -ve to t'other end of each strip.

Graham

Unless otherwise stated all posts are my personal opinion 

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Parallel cos in series and they will become dim as the voltage is spread across the strips. Still arrange them in a pattern but make sure the +ve 12V goes to the +ve end of each LED strip and the -ve to t'other end of each strip.

It doesn't work like that with the strips, +ve and negative are available at both ends of the strip.

J

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  • 2 weeks later...

I've used these RGB 5050 led strips over Christmas for the first time.

 

Put mine in a daisy chain, using bought connectors, theres a few youtube videos showing you how to connect etc.

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Good point John. For some reason I'm trying to over complicate things.

 

One project will be running from a 9v battery so I'll have to work out how long it will last as I believe parallel draws more power.

 

Where do you buy your bare tinned copper from john? Checked eBay and can only find insulated so would need stripping.

​Mains cable - either hard or flexable

Skoda Scout 4x4 pulling a coachman Amara 520/4 at 93%---- when full!

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Have fitted L. e. d's to quite a few vans use the both ends system found it the best way . With the tape 50/50 size they only get warm -its the Cree's that get b--dy hot ! ( as good as a halogen bulb ) On the tape set up you are restricted to a minimum size of 3 leds because of the built in resistors

Skoda Scout 4x4 pulling a coachman Amara 520/4 at 93%---- when full!

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Hows it going MM, have you done it all yet??

 

RT

Hello there.

The answer is yes and no.

I have not done anything on the van yet but I did do an LED conversion on something else.

I'll be adding it to my blog when I get the chance along with pics and an explanation of why I have not altered the van yet, though that will be next!

 

Edit: Thought I'd add that I've just finished it today and did intend to report back. And I did it in parallel.

Edited by MonkeyMark

Just beginning our adventure. 95% of my time on CT I use my phone. As a result correct spelling and grammer will be used sparingly. This is due to fat fingers. Please don't let it bother you.

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Parallel or series, the power consumption will not be different. However, if the strips have their own resistor packs, wiring in series will reduce the brightness.

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Parallel or series, the power consumption will not be different. However, if the strips have their own resistor packs, wiring in series will reduce the brightness.

 

How does it reduce brightness without reducing power consumption?

 

Parallel is the only way to run them unless you have 24v supply.

Edited by Guest
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Parallel or series, the power consumption will not be different. However, if the strips have their own resistor packs, wiring in series will reduce the brightness.

Plus if one led goes down they all go out ( series )

Skoda Scout 4x4 pulling a coachman Amara 520/4 at 93%---- when full!

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I'm not sure how my 5050 are wired internally, there is a tiny sm chip not sure what it is for each led, which as mentioned earlier are in blocks of three.

 

But as the strip came in a 5M length it seemed logical to connect them the same, I bought a complete kit to keep things simple. And they do run with some heat on full brightness.

 

http://www. amazon. co. uk/YAGGU-SET-Changing-Flexible-brighter/dp/B007H39XLA/ref=sr_1_2?ie=UTF8&qid=1389452694&sr=8-2&keywords=5050

 

I also bought these to connect, as the connections are tiny going the soldering route.

 

http://www. amazon. co. uk/Connector-Cable-Adapter-Stripe-Waterproof/dp/B009WE70VC/ref=pd_sim_light_4

 

 

I use mine to supplement my tropical fish lighting, but due to the heat they can produce I wouldn't want to fit them to my caravan.

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I'm not sure how my 5050 are wired internally, there is a tiny sm chip not sure what it is for each led, which as mentioned earlier are in blocks of three.

 

But as the strip came in a 5M length it seemed logical to connect them the same, I bought a complete kit to keep things simple. And they do run with some heat on full brightness.

 

http://www. amazon. co. uk/YAGGU-SET-Changing-Flexible-brighter/dp/B007H39XLA/ref=sr_1_2?ie=UTF8&qid=1389452694&sr=8-2&keywords=5050

 

I also bought these to connect, as the connections are tiny going the soldering route.

 

http://www. amazon. co. uk/Connector-Cable-Adapter-Stripe-Waterproof/dp/B009WE70VC/ref=pd_sim_light_4

 

 

I use mine to supplement my tropical fish lighting, but due to the heat they can produce I wouldn't want to fit them to my caravan.

 

Chips on the amazon picture are resistors, one for each colour led in the tri colour LED.

RT

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Good point John. For some reason I'm trying to over complicate things.

 

One project will be running from a 9v battery so I'll have to work out how long it will last as I believe parallel draws more power.

 

Where do you buy your bare tinned copper from john? Checked eBay and can only find insulated so would need stripping.

Fairy lights inside tubes with what looks like bare wire: This wire is very special in that you can solder through the insulation! You just need to use a fairly hot iron and cored solder while holding the wire where you want it and even just wrapping joins together before soldering. For soldering to tiny lands like led strips it is best to tin the end of the wire first - just touch the end with the hot iron and solder. Stripping varnish insulated wire is really not necessary.

Bailey Pageant S7 Burgundy - Very comfortable two berth van, towed by a Citroen Xantia HDI 2. 0.

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Chips on the amazon picture are resistors, one for each colour led in the tri colour LED.

RT

There appears to be only one resistor for each chip?, but as the forward resistance is different for all three colours you could be right, anyway this pin out data helps explain.

 

http://dlnmh9ip6v2uc. cloudfront. net/datasheets/Components/LED/5060BRG4. pdf

 

My previous experience of leds was only using the same colour, where the leds could be wired in series with out a resistor, the number of leds in series depends on the supply voltage, to keep the current with in range, usually 20ma.

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There appears to be only one resistor for each chip?, but as the forward resistance is different for all three colours you could be right, anyway this pin out data helps explain.

 

http://dlnmh9ip6v2uc. cloudfront. net/datasheets/Components/LED/5060BRG4. pdf

 

My previous experience of leds was only using the same colour, where the leds could be wired in series with out a resistor, the number of leds in series depends on the supply voltage, to keep the current with in range, usually 20ma.

Should have said forward voltage.

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Should have said forward voltage.

 

I knew what you meant and in effect it's the same. I would suggest that three of each led colour are in series and then a resistor is in that chain providing suitable current limiting. So in each group of 3 tri colour LED chips there will be 3 resistors which may look like one per LED but it's not.

 

Regards RT

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That makes sense, I don't know anything about SMT apart from the fact that I can recognise SM when I see it.

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