AC-LED Night Lamp

INTRO.

This AC LED Night Lamp is dedicated to my friend and adviser *qs*. Without his help I could not have done it.
This Night Lamp runs on AC and is also a Emergency Light when run on the UPS of your PC. during power cuts.

Step 1 STEP-1

FIXING THE LED's

First of all we will fix the LED's to the Perforated Hard Board.
Fix a row of 5 Blue LED's each on both sides of the Perf Board.
Then fix 6 rows of 5 White LED's in between the rows of Blue LED's
That is in total 10 Blue LED's and 30 White LED's = 40 LED's.
After fixing the LED's to the Perf Board we will wire the Circuit.
Please see the next Photograph for guidance.

Comments

[fcat1]

Hello mate,

From your 10mm LED AC light, with 18VAC (25.2 Vpk), u have 2 parallel sets of (6led x2) connection correct ? Roughly how many more 6x2 led can be parallel added to it ?

What if with household 240VAC, a .22uF & 1K ½W resistor, 7led x2, any limitation of parallel connection ?

By adding one Bridge Rectifier, should be able to filter the flicker effect right ?

[Dipankar]

On 240VAC, a .22uF & 1K half Watt resistor,
you can put up to 30+30 led's on a 500 milli watt 12 volt step down Transformer.
If you put more then 30+30 the light starts to go dim, but it will glow.

[fcat1]

Read lots of your post & QS's, about using LED with AC,

The max number of LED can direct connect to household is 240 * 1.4 = 336Vpk 336 / 3.3 (led Vf) = 101 minimum number of LED directly connect to VAC.

1) With lower number of LED, I need a .22uF & 1K ½W Resistor, does this C + R set support, as randomly as 45 + 45 led's ?

2) With this C + R combo, does it support four legged Superflux LED ?

Thanks mate : )

[Dipankar]

101 minimum number of LED directly connect to 240 VAC.
Your calculation is correct but it should be 101+101LED's.

Regarding four legged Superflux LED, I have no idea, never used it.

[knektek]

in the schematic you used a step up transformer. its supposed to be less windings on the secondary coil.

[Dipankar]

It is a step down transformer, sorry to have placed the transformer in the wrong direction.

[qs]

Hi DP,

Without getting the design too complicated, you can maximize the flickering effect by doing the first "TA" as 1 leg, then the ending "TY" as the other leg, and mix the centre "S" with LEDs from both legs. In general, the further apart you separate LEDs from each polarities, the more obvious you will make the flicker.

Your mains is 50cycles, so each leg is actually running at 25cycles = more flicker than 30.

See the image below as an example: red dots would be + polarity and dark dots would be negative.

[Dipankar]

Hi qs, How do I connect this to the mains? because LED's are a one way street.

[qs]

Use this schematic. Values in (brackets) are for US voltages. For added safety, add a 1N4007 diode in each chain facing the same way as the LEDs. This stops the reverse voltage to get too high should one chain stop working.

[netbuddy]

Where is the bridge rectifier and regulation? I hate to say it, if the output is only 12 volts, it is still AC and 240VAC or 12VAC, you can still seriously hurt yourself or even end up dead. Respect electricity, even a low voltage is dangerous.

[12V]

leds are diodes!

[netbuddy]

The have that property, too much reverse voltage and "POP" they go.

[zimmemic25]

the simplest rectifier would be 4 diodes, one straight on every ac line (different directions) and crossed (same direction like the straight diode connection) connections to + and - because this isn't an asciiart-friendly board, ill have to try to explain: (~1) (+diode-) (-) (~2) (+diode-) (-) (~1) (-diode+) (+) (~2) (-diode+) (+)

[olie854]

your schematic is eligible plus and minus wires seem to be connected I cannot tell where you hook the end of the led strings to even though i already know, And if you are going to mess with act there is no plus and minus wires act is alternating current meaning at one point one wire is + and the other is - then 1/120th or 1/100th of a second later they flip and it continues, now what makes it an emergency light maybe no power, oh wait it needs electricity to operate, what would you use it for. this kind of thing can be bought in a dollar store or thrift shop even online kind of a waist of LED's in my eyes.

[Dipankar]

Hi olie854,
Read the second line in INTRO "This Night Lamp runs on AC and is also a Emergency Light when run on the UPS of your PC. during power cuts."
It works that's all. If you cannot follow the circuit Diagram then I can't help it.
I have used + & - because there has to be a Phase(+) and Neutral (-) in every cicuit.

[zimmemic25]

its AC, so the correct signs would be (~) <---> (~), not (-) ---> (+)

[olie854]

added to my comment the + and - on the LED's is sooooooooooo confusing also you have a connections on the bottom left and bottom right that have no connection dot should there be one I assume so.

[Dipankar]

Dont go for DOTS see where it is connected.
5 rows of LED's are connected alternatively so that when the AC current flows, it goes through the ROWS alternatively, and half the time one row is on and the other is off.
You can forget the (+) & (-) of the transformer as it is AC.
This Diagram is for those who do not have a college education like me.
We do everything in practical and it works.

[zimmemic25]

if you "do everything in practical", and don't even make correct diagrams, then i wonder y you are still alive.

[olie854]

college education I am in high school any one can Google these sort of things to find what they need i learned what everything is and what it does with a buddy and the Internet, you don't really need to be smart to read or write a schematic you just need to know what it means.

[zimmemic25]

agreed. and i want to add: there are some books, i dunno if Dipankar likes reading much, but fact is, i'm 14 now, and i'm building a robot. with age of 8, i built my first full adder, because you can read all these things in internet or books.

[lolzertank]

LOL! I built my first full adder at the end of 2nd grade... 8 years old too! Though I'm not making a robot...

[zimmemic25]

ok, update: my robot project paused, i didn't find a battery for powering it without being too heavy for being transportet by the bot. i think the problem was the fact that i was using an IBM/Lenovo T30 as control unit, which simply is too heavy for my motors.

[lolzertank]

Try using cells extracted from lithium drill batteries. The Dewalt 36V is a good choice since it's stuffed with 10 A123 26650 M1 3.2V 2.3Ah cells that can each supply 70A, more than you should need for a robot. The A123 cells are as safe as nickel (NiCD, NiMH) chemistry too. You'll need a hobby charger with a "LiFe" setting and run times might not be the greatest. The good thing is, with a proper charger, the A123 cells can be charged in 20 minutes. RC packs could work too, but LiPOs are very dangerous if abused.

[olie854]

OK I see that you can use it on a ups but the plus and minus at the end of the led string are useless even confusing get rid of them i did not understand that you wanted them in parallel loops and what are the little arrows on the LED's the current always flow from the anode to cathode in the direction of the triangle. but still ac is ac no + no - it alternates so the + and - on the transformer is wrong. you also have the emergency light well nothing changes unless you switch so how does that make it an emergency light also would a rocker or toggle switch be easier those switches can be difficult to move sometimes and there is little grip on them.

[zimmemic25]

the little arrows on the LEDs are light. if there werent arrows, it would be diodes. but with arrows, it are something emitting diodes, where the something is mostly light, so LED sign is diode sign with arrows.

[Dipankar]

Dont go for the DOTS
See the continuity of the RED and BLACK lines, they are all connected.
Got it?

[oninkanin]

Hello Dipankar, i am Nino from the Phillipines, i an working in CBN Asia, i am the systems engineer here. I just want to say thank you for your design and your heart to publish it on the web. It is indeed a great help for us. I utilize your idea and make it as our lighting system on the studio. I made one color (white) only and put some gels for corrections. It is great and consume less power. What i am trying to work out now is how to make a multi color LEd lighting, any advise??? Anyway I dont know if you believe me, but surely what you are doing has eternal rewards. continue to share your knoowledge brother. THANKS!!!

[treg]

I'm sorry to say that there are betters ways to supply power to the leds than using a transformer, you can make a current generator using just one condensator. Plus, adding a $0.5 diode rectifier would not hurt, and with another capacitor you would get a constant current source. The total cost would be about the same as the cost of the transformer (almost nothing), and you'd get twice more light and longer leds live. Anyway, I like the idea of the panel. I was planning to made one, I just could not find 5mm perforated fiberboard yet :D

[Dipankar]

Dear treg, I am also sorry to say that your idea of condensator did not work out as I have used 160 LED in my next Instructable "LED CHANDELIER" which will be published in a few days. One condensator was unable to light up all the LED's and using more than one condenser becomes very costly.

[treg]

Is it possible that you share the precise schema you used ? I made a lamp with 120 warm white 25mA leds, using : -1 condensator to make an alternative current generator, -a diod bridge and a second condensator to get constant intensity, -6 lines of 20 leds (so the rectifying condensator don't get over-voltage if one of the leds get faulty) -6 resistors to match the luminosity of the 6 lines (and also lower the rush current). It worked perfectly (except that I did not like the "pure" white leds I hade) using the standard formula to calculate the value of the condensator).

[Dipankar]

Hi treg, For lighting 120 LED's you have used ... 2-Condenser 4- Diodes for bridge 6- resistors Total 12 items. whereas for lighting 160 LED's I have only used one Transformer, thats all.

[treg]

condensers + diodes + resistors costed me 2€. Also, if I accept to have leds flashing at 50Hz (or 60), and not really care about a very little difference between the lines of leds (I could use only 2 lines and match the leds so avoid any difference, I used resistors because I have hundreds of them left and because I wanted to match different flavour of "white" leds), I could do with a 1.5€ condenser alone. The reason why I like the transformerless solution is because I can reach nearly 100% efficiency, with a cheap transformer, I assume to be at about 50% efficiency (or maybe up to 60-70 with a bigger / more expensive transformer). I also like this solution because it takes very few room. BTW, there are also reason why I do not like it (the main reason is safety : I make all my less-than-ten-leds using cell-phone charger than I usually find in garbage cans : safe and free. I would not let my 8 year old nephew play with my 120 leds lamp !)

[remmelt]

Are you saying you have your LEDs hooked up directly to mains? There's a reason that's not legal. The reason is, it's dangerous. I don't think Dipankar's solution is perfect but at least he has separation between the light and the mains grid. Why not make a safe compromise with a transformer and a rectifier? That way you have safety and decent efficiency. Or you could buy a cheap wall wart and be done with it (but where's the fun in that!)

[Dipankar]

Hi remmelt, SEE STEP-2 DON'T YOU SEE THE 12 VOLT TRANSFORMER. YOUR MOBILE'S BATTERY CHARGER IS ALSO PLUGGED INTO THE MAINS, is it dangerous? Look at the circuit Diagram. all modern equipments which are plugged into the mains use a transformer INSIDE, your PC , TV, Stereo etc. Where did you see the LED's are directly hooked to the mains. LOOK AGAIN.

[remmelt]

Hey! I wasn't talking to you, clearly I can see your transformer :) Where I live (the Netherlands) it is illegal to hook up something like this to mains directly because it is unsafe. A transformer gets you separation between you and mains, which is good. Treg's solution doesn't offer that kind of safety, and that's why I responded. The mobile's battery charger is a transformer as well, and thus safe. Just don't touch the parts that are connected to the mains, but I guess we all know that ;)

[Dipankar]

Hi remmelt, I am sorry, I misunderstood your comment. Now I see It was for treg.

[treg]

-It is not illegal where I live (you still have to take some care of course). It is not more dangerous than wiring a 110/230 light bulb to the main (of course, you must protect the led as well as you'd protect the light bulb). -Using a rectifier will not give better efficiency (it will give poorer efficiency because of voltage drop across the bridge), but it WILL give twice more light per led. Also, if you use a cheap wall wart (which IS an acceptable solution), be sure to mesure the real voltage it gives under load, you will find that it can be very different from the expected one (one good solution is to use a potentiometer set to the correct theorical valu, then use an ampermeter to set the current to the correct value, then unplugg the pot an measure the needed resistor value).

[code_e]

How does one make a "current generator" using only a single condenser? I haven't heard of this before.

[treg]

Basically, the power source is an alternative voltage generator, so if you put a condenser, it will continuously be charging / discharging, Since the basic condenser law is Q=CU, with Q being the charge of the condenser, C its value and U the tension (voltage), you know that dQ = C.dU ("d" means variation). The variation of the charge (dQ) is the intensity (I), and dU is easy to calculate if you know the maths.

Of course this will not be as simple if the load makes a non-constant voltage drop, but here you will have only leds driven by a constant current, with rectifier diodes and a condenser to make constant current, so you can consider that you have a constant voltage drop, and accept the previous affirmation.