LED light strips for basics

Thread Starter

@vajra

Joined May 2, 2018
154
Hi everyone

I would like to make LED light strips for home decoration I have included an image below which explain my understanding for LED light strips circuit
.I hope someone helps me with what I am trying to achieve and explain it in a very basic way.

upload_2019-6-3_11-41-33.png

What the best way of doing this would be, and exactly what parts I would need to give this a professional finish.

Thanks for any help in advance...
 

ericgibbs

Joined Jan 29, 2010
10,484
hi va,
The top circuit in your posted image is the most efficient when using a 24V supply.
Post details of the LED's ie: forward voltage drop and current.
E
 

MisterBill2

Joined Jan 23, 2018
6,728
Certainly there is a huge range of "LED light strips", some really great and some are junk. There are two basic kinds of LEDs, which are the kind with lead wires and the kind that surface mount, usually to some sort of printed circuit board arrangement.
In addition to using a series resistor there are a wide variety of electronic regulator circuit designs and products available. And one big caution to keep in mind is that LEDs are diodes, and so polarity matters, and that many LED types have a lower peak reverse voltage rating, which means that connecting them backward can damage them if the voltage is beyond that rating.
The LEDs with wire leads are easier to work with unless you have a circuit board to solder them to, and a good deal of soldering skill.
 

Thread Starter

@vajra

Joined May 2, 2018
154
hi va,
The top circuit in your posted image is the most efficient when using a 24V supply.
Post details of the LED's ie: forward voltage drop and current.
E
"LED Light Strips" can mean a million different things.
What do you want exactly?
Certainly there is a huge range of "LED light strips", some really great and some are junk. .
I want to make LED Light Strips as shown here https://www.google.com/search?q=blue+led+strip+lights&rlz=1C1CHBF_enIN805IN805&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjJ_7Ktkc3iAhWPeisKHViRCJ0Q_AUIESgC&biw=1242&bih=597#imgrc=5Yo4gDidRKmgPM:
 

Dodgydave

Joined Jun 22, 2012
9,316
If you're making it for yourself, the top one is the simplest, if you're going to use a lot of leds in the strip, the bottom one will be better.
 
Last edited:

Picbuster

Joined Dec 2, 2013
1,020
Hi everyone

I would like to make LED light strips for home decoration I have included an image below which explain my understanding for LED light strips circuit
.I hope someone helps me with what I am trying to achieve and explain it in a very basic way.

View attachment 178876

What the best way of doing this would be, and exactly what parts I would need to give this a professional finish.

Thanks for any help in advance...
using the top one:

Total Led voltage @ I V_forward = N x V_forward) N number of leds
Resistor =( 24- Total Led voltage) / I @ V_forward
Energy in resistor (W) = resistor x (I @ V_forward)^2

Picbuster
 

dendad

Joined Feb 20, 2016
3,595
If you use the bottom circuit, your 24V supply current will be 6 times higher than the top one for the same LED current.
I would use the top one. Do you have the skill to make a strip like you posted?
That ia surface mount. And on flexible circuit board.
Alec_t is pretty correct in that it is a good idea to buy it ready made.
How do you intend to mount it all?
Are you aiming for "birdsnest" construction or do you think you can get some other mounting system?
I'd be interested in your ideas for the mechanical side of it all.
 

MisterBill2

Joined Jan 23, 2018
6,728
If you are going to produce a light strip 2m long and put the LEDs at 1cm spacing then what makes sense is a hybrid arrangement using a common 12 volt supply. If the LEDs have a typical forward voltage of about 3.1 volts at a reasonable current then you can put them in groups of three and a series resistor for each group. That will be a standard setup and will keep the power dissipated in each series resistor to a reasonable amount. It will also allow you to check your work frequently as you are building the string. The big challenge is that surface mount LEDs look the same forward and backward, but they only work connected one way.
Now I have some advice, which is to look at a manufactured string of LEDs with a good magnifier before you start the project, so you can see exactly how it goes together. The project is not as simple as it seems. You still need to have the two power wires running down the sides and you need to be able to solder to them, and between the LEDs, and that means a lot of good soldering. GOOD LUCK!!
 

dendad

Joined Feb 20, 2016
3,595
A thought I just had, can you get ant TV ribbon?
That may make a good base to build a LED strip on, using through hole LEDs ans resistors. A 3mm hole could be punched through the ribbon and the LED pushed through. Connections hidden on the back side of the ribbon. Spray well with clear varnish when done to sort of waterproof it.
At least that is one idea. Now I may get to sleep as it is after midnight here.
 

MisterBill2

Joined Jan 23, 2018
6,728
A thought I just had, can you get ant TV ribbon?
That may make a good base to build a LED strip on, using through hole LEDs ans resistors. A 3mm hole could be punched through the ribbon and the LED pushed through. Connections hidden on the back side of the ribbon. Spray well with clear varnish when done to sort of waterproof it.
At least that is one idea. Now I may get to sleep as it is after midnight here.
I had not considered using 300 ohm twin lead, that is an idea. But nothing sticks to it and so the fabrication would need to be with the through-hole style of LEDs and those would need a hole punched and that assembly would be much harder to do well.And consider that a whole lot of holes of exactly the right diameter and spacing would need to be punched, and also a whole lot of places the insulation removed, it would certainly be a large exercise project.
 

BobTPH

Joined Jun 5, 2013
2,503
I cannot imagine that you could make anything as good as the ones offered commercially for less money.

Any mass produced item is cbeaper than a one off DYI version with the same quality.

I try to limit my efforts to things I cannpt buy cheaply or, more often, at all.

Bob
 

Thread Starter

@vajra

Joined May 2, 2018
154
Alec_t is pretty correct in that it is a good idea to buy it ready made.
I cannot imagine that you could make anything as good as the ones offered commercially for less money.
I totally agree with bits of advice but If I buy, I will not be able to learn I am taking it as project If I make myself, then I can learn much from myself. I think, the first thing we should know the requirement, required parts and design

I know my requirements and I have also shared my circuit so I think I need to select components

some points

1) Right now, we have not come to a conclusion about which circuit we should implement first or second
2) My calculation is for 24V, I'll power strip from 24V SMPS
 

djsfantasi

Joined Apr 11, 2010
6,718
I totally agree with bits of advice but If I buy, I will not be able to learn I am taking it as project If I make myself, then I can learn much from myself. I think, the first thing we should know the requirement, required parts and design

I know my requirements and I have also shared my circuit so I think I need to select components

some points

1) Right now, we have not come to a conclusion about which circuit we should implement first or second
2) My calculation is for 24V, I'll power strip from 24V SMPS
Funny, I thought that was answered. The second circuit will require much more current than the first circuit. Six times. Calculate the current required by both circuits and see if your supply can handle it.

Also, in the first circuit, if one LED blows, your entire string is dark. You can minimize this problem by wiring the LEDs in series-parallel.

As several people have noted, you may want to consider a third circuit, with fewer LEDs in series. Three LEDs in a series string, and all strings wired in parallel is how commercial strips are often wired.
 

Reloadron

Joined Jan 15, 2015
5,611
Here is an example of how one strip I have is wired:
5050 LED String.png

The left side of the drawing is an example of using 5050 RGB LEDs. The strip uses 12 VDC power but they are available in other voltages also. I can buy a 5 meter (16 foot) strip which is easily cut to smaller strips for about $16 USD and I can't make a strip that easy or affordable. I agree with those who say better to buy than try and build.

Ron
 

AnalogKid

Joined Aug 1, 2013
8,536
5 LEDs in 2 m is pretty spread out, but if that is the entire unit, then nothing will be more simple and more efficient than the upper schematic in post #1. One major advantage over the lower sch comes if you daisy-chain multiple strips for more length. The upper sch draws 20 mA per group, while the lower one draws 120 mA. Assuming the same 20 mA per LED, it needs one 330 or 360 ohm (343 ohms calculated) per LED. That is an extra 100 mA per downstream string that the first string has to pass on. With multiple strings, a 6:1 difference in current affects wire size, connector type, and power supply capacity.

ak
 

MisterBill2

Joined Jan 23, 2018
6,728
I totally agree with bits of advice but If I buy, I will not be able to learn I am taking it as project If I make myself, then I can learn much from myself. I think, the first thing we should know the requirement, required parts and design

I know my requirements and I have also shared my circuit so I think I need to select components

some points

1) Right now, we have not come to a conclusion about which circuit we should implement first or second
2) My calculation is for 24V, I'll power strip from 24V SMPS
OK, my mistake in thinking the supply would be 12 volts. So here is the suggestion, along with an explanation, which works if you select LED devices that are intended to work with a forward voltage drop of around 3 volts. That is about what many of the high brightness white LEDs run. So this suggestion is based on 4 volt white LEDs. The circuit would work best as a hybrid of the two circuits, with groups of 7 LEDs in series with a current limiting resistor, all across 24 volts. The resistor value must be set to limit the current to the selected value, probably 50 milliamps. You will need to experiment and discover what the voltage across an LED is with the current at 50 mA. That voltage must be multiplied by 7 and subtracted from 24 volts to find the voltage that must be dropped across the series resistor with a current of 50mA flowing. The same value can be used for each string of 7 LEDs. The hard part will be figuring out how to space groups of 7 LEDs along the strip so that it comes out even.
Using 300 ohm twin lead cable is a great idea if you will be using through-hole mount LEDs. If you choose to use surface mount LEDs there may be some sort of suitable material available, but I am not sure how it will work. Possibly you could fabricate groups of 3 series strings on each section and then couple the sections. At that point the hard part will be the mechanical arrangement. Of course, if you can produce a printed circuit board pattern with groups of 7 LED strings then it could work very well. But since I have no clue as to your mechanical skill set All I have is guesses on the mechanical part.
 
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