Convert supply from AC to DC

Hi Everyone,

I hope I'm at the right forums, anyway, I have a LED light bulb which takes in AC as source AC180V-250V 60HZ, and outputs 1W, if I were to convert its power source to DC say 12V, what are the things I need to do? compute for?

I also want to create a dimmer switch sort of like a speaker volume, is it possible without busting the LED bulb?

Thanks in Advance!

 

Welcome to the forums!

Did you mean 120-250V?

Is this a 1W light bulb? Why do you want to feed this light 12V DC?

Sorry for so many questions - just trying to get a better handle on what you have and what you'd like to wind up with.

 

Are you sure it wasn't 100-280V? Why would you want to run it on 12VDC?


As for the reason it's 100-280V, Japan uses 100V while North America uses 120, 208, 240, 277V and Europe, Asia, Australia, South America uses 230-240V.

 

"I also want to create a dimmer switch sort of like a speaker volume, is it possible without busting the LED bulb?

I thought, but could be wrong that LED's were either off (not enough voltage), on (more than the min voltage), burned out (too much voltage). Dimming being accomplished by electronics that cycle between on and off very quickly.

If this is a long run of wire I think (but don't know) DC power loss due to resistance is higher than AC and the wire should be hotter.

I would think Solar or Automotive or Boating people would deal with the issue regularly. Westmarine type places should have info on 12v DC LED lighting.

 

It would help if people would put their actual location...in this case the Philippines...and explain WHY they are trying to do what they ask.

 

Did you mean without breaking the LED bulb.....or blowing up the LED bulb.....or even burning out the LED bulb?

 

To summarize to everyone's reply,

Yes, Casual Joe

Hi geor8ge, say if the wire would only run by a maximum of 5m? would it be hot, can I subdue the heat by adding a resistor or fuse somewhere?

Where is this Westmarine? do they have any site/forums?

Hi Justin Smith, would it make a difference if its not 100-280V? I think this sort of things are somewhat starting to become auto-volt in nature as manufactured. What will be the impilication/s if this would not be considered?

I was asked to do this project, to resolve heat from wires and make sure the a power source such as a car battery would be able to supply the necessary voltage to power the bulb, without blowing it up nor burning the wires. It's a DIY project,

Hi Nashkat1

The bulb packaging says AC180V-250V 60HZ, yes a 1W light bulb to be powered by a 12V DC for a DIY project


To Everyone:

It's my pleasure being asked/interrogated, I need to learn so I must adhere to the questions to get as much information and help from somebody like you.

I know this can be done, but I need some proof of concept, because as I understand the difference here is just the power source, I suppose I just need to put something in the middle between the bulb and the battery.

And yep, I'm from the Philippines, we got AC here at 220~-240~

Thanks in advance.

 

Hello mirageservo,

LEDs are powered by DC, the circuit in the lightbulb is actually converting the line voltage (220V AC) to a low DC voltage (~5V DC).

The "Dimmability" of the bulb is based on this same circuit, some bulbs like this dim very nicely on a typical wall switch dimmer, others don't and are designed for "Full On" operation only (because the circuit will cut out if the voltage is reduced). The packaging typically indicates whether or not it is dimmable.

The only way to power the LED bulb with DC without modifying it is to provide enough voltage to turn on the circuit, this could possibly work with as little as 5 volts or may require 100 volts DC or more.

LED life is dependent on the quality of the driver circuit and the heat dissipation of the assembly. For an unmodified LED bulb you probably can't hurt the LED without putting more than 240 volts on it, it may work just fine with 12 volts DC actually, but it totally depends on the circuit inside the base of the bulb.

 

Hi mnmattmn,

This is a good point, it never crossed my mind though, anyway, still I have to disassemble the bulb to remove the base and see the conversion if its really happening.

Is there any other way than disassembling it?

Thanks

 

Have you selected the LED you want to power up ?

Can you leave us a link to it.

 

Many other ways, but they all require providing sufficient voltage for the LED circuit to operate at full capacity, probably around 150 volts DC. A power inverter like for a car can convert 12V DC from a car battery to 240 VAC. That's the best way to get there without building your own circuit.

 

Search their site, but I can't find anything, anyway, I took a shot at the label when I bought it.

 

No Links but I got pic of the labelling

 

Hi mnmattmn,

150V in DC? How can I produce such power when my source is just 12V DC? What if the power source is just 12V?

A question about the inverter, where will the inverter get its power source, in the power outlet? what if the only source is just the car battery?

 

Seems a waste of money and effort though when you can just buy LEDs that are 12 volt DC. Why must it be that bulb?

 

Try firing it up with 12V DC and see what it does, it might be sufficient to light a 1Watt LED. Put the positive on the base of the bulb and the negative on the threads.

 

Hi mnmattmn

It didn't light up, however, I tried opening (dissecting) the LED bulb and found out that there's just an AC to DC conversion going on, (as I understand it), given this, if I were to remove the conversion and attached the LED +/- poles directly to power source, how much power rating should I provide to ensure that the LED will light up and will not be busted/blown? Should I put a fuse, Initially a car 12V DC would be the power source.

 

Just a caution. An LED is just a diode and you should not apply a DC voltage to it without a current limiting resistor. Calculating the proper size requires knowledge about the characteristics of the diode itself. Just don't want you to try it when it will fry just after it lights up.

Bud

 

If you opened it up it is probably a single die 1 Watt LED. Check to make sure that there is only one LED looking component, let me know if there are more.

White LEDs typically have a forward voltage of a little over 4 volts and since that one is rated to 1 Watt you can safely apply up to 0.07 amps at 12 volts (assume 14volts for safety margin)

So you need to limit the current to 0.07 amps max, but you'd like to dim it down to .01 amp. You should be able to limit the current using a 125 ohm 1/2 watt resistor in series with a 1k Ohm 1 watt pot (volume knob).

The 125 ohm resistor should be wired from either side of the LED to the middle or sweep pin of the 1k potentiometer, and one of the other pins wired to the battery. The 125 ohm resistor will act as a fuse and burn up before the led is damaged (if it is a 1/2 watt resistor).

 

Hi All,

I have attached pics here of what it looked like, anyway, I think I need to create something similar control as seen on the pics but instead of an ac source, it should be dc.

Where should I start? assuming a car battery is the only power source.

 

This seems obvious, but hasn't been responded to (or I missed it):It helps us provide better-targeted advice more quickly if we know where the question is coming from. To that end, would you please remove "CAL," a U.S. state, from your profile and replace it with "Non-US," unless PHILIPPINES is actually available as an option? (It would be cool if it was.)

 

I don't think it's just right to follow somebody's advice because they say it was obvious,

In my own opinion, I don't think this is a waste of money, the question should be how much are you willing to spend in terms of money, time and effort to build something. (as long as you know its making sense, its not a waste)

Let me ask you, where can I buy a bulb of DC source that's below 300PHP or say @45/$ that is $7, do you have any idea?

This bulb cost around 165PHP or less than $5, apart from that the fact that you are trying to do something opens you to something intangible that you could make use in your future endeavor and what is that? LEARNING... I think what makes people stop to think are these people that tells them its obvious, obvious what? obviously a failure? If you won't try, you won't know... and I hope you understand.

I came here to this forum because I believe it could help me instead of putting me down... There is no such thing as a stupid question only stupid answers.

If in case it fails, then I learned my lesson, and failing to realize that again on my future works/projects is what you can or those who wants to say that its obviously dumb.

I have change my location as you requested, I didn't realize it was there.

I was still hoping I could make this work... I know I can..

Thanks for burning my desire to soldier on. I'll keep you posted.

@mnmattmn

I would love to discuss your suggestion further, have you seen the pics I have posted?

Thanks,

 

Looking at your pictures you'll see a red and a black wire connecting the LED assy. to the board. That is going to be a low voltage connection.

Do you have a supply of resistors there and a VOM meter ?

That board converts the higher AC voltage to the lower DC voltage. Without being able to read the part numbers we don't know what the DC output voltage is supposed to be. Since there are ten LED's and it appears that they are connected in series, 12vdc may not be enough to light them.

I would try connecting the red(+) and black(-) to the 12v source with a resistor of 100 ohms at 1/2w in series with one of the wires. See what the LED's do. If they don't light or are dim....try reducing the resistance down to 30-50 ohms.

 

if you can measure the voltage across the LEDs (from the red wire to the black wire) and the voltage across a single LED when the light is on we can help you more exactly, but you can also try the "shotgun" approach and try this if you don't mind possibly damaging some or all of your LEDs:

It's a fair assumption that each LED has a Vforward of about 4 volts, meaning the power supply must provide at least 4 volts to turn on the LEDs, so right now it takes about 40+ volts DC to turn on 10 LEDs. If you can cut some of the LEDs out of the circuit you will eventually get the LEDs to turn on with 12 VDC...

I would start with 4 LEDs, and if that doesn't work go to 3 (safer to start with 4, then go to 3 -- less likely to burn out the LEDs that way). Then, if you find success with 3 or 4 you can wire an additional set of 3 or 4 in parallel, and you can add a resistor in series to the remaining 1 or 2 LEDs to get them all to light.

 

By all means, soldier on.