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When you need to convert voltages, you almost always need a transformer or inductor of some sort, at least if you want to do it efficiently. Linear power supplies will use a large 60Hz iron core mains transformer, switchmode power supplies and commercial LED drivers will more often than not use a small ferrite or iron powder transformer.
However, if you do not need a lot of current, using a small high voltage capacitor in series with the full bridge rectifier should work, the capacitor will impede the current, and the rectifier will give the LED the DC that it needs. (it should be noted if you choose to do this, that it is very dangerous, and you need to use the right type of capacitors, and there will be some math involved.)
A better solution would be to use high voltage LEDs specifically designed to be driven with mains voltages. CREE has some good really efficient high voltage LEDs, and there are these things called "LED filaments" which are really cool!
Your answer is right. I want to make a circuit like this so can you give me circuit diagram that have a out put of 12v and 300mA this capacitors.
electronicsNmore has an old video about doing this, however, note that he is 'sane' and uses much smaller LEDs. You cannot safely achieve powering that 10W LED with capacitor. However, if you are determined to at least try, then definitely use the MOV and fast-acting fuse protection. A 4.7uF capacitor will get you close to 300mA peak.
That is a 10W (+) Led...
It is designed to handle 900Ma @ 9V
I would suggest Using a "LM317" in "Constant current mode"
Grab a ( 12Volt 2Amp+ ) Power supply and use *This Calculator* to tell you what Resistors you need to to Safely Drive this Led.
Looks like you need a 4.2 Ohm ( 1/2 Watt) Resistor between the ADJ pin and the Output. (Diagram is on the Link)
It's a nice, Simple & Reliable, Circuit that will cost maybe $3
You will still need a few Capacitors, but they are cheap and easy to use :)
Let me know if you need some help to Get it going ! :D
I dont want any separated power supply . I want to make a full supply that input 220v from ac mains! and give the out put to drive this
Really Dangerous Idea....
Any Commercial product will Use some sort of a transformer. Certain led bulbs don't use one because they have Enough leds to safely drop the voltage. (220V / 3.2V per led = 69 leds + a Resistor) or in your case (220V / 9V per led = 25 leds + a resistor)
You also need to limit the current. if you don't you will burn out the led quickly if not Instantly. They are cheap if you want a simple one Here is the First one that I found on Ebay But really you may want to spend a bit more for a more reliable one. Your local hardwere store should have whats call a "12V Lighting Balast" For 300ma you want the 1-Watt version.
Still if you want to try (*Please do not*) you will need to use a "Bridge rectifier" to change ac to dc voltage and you will need a 800-Ohm 75Watt resistor It's about 1 inch wide,6-7 Inches long, $25 (+ shipping) and will get Extremely hot ! (You could cook a Steak on it)
Forgot to mention, whatever method you use to power it Grab a beefy Heat-sink. if your only running it at 300ma you should be safe but if you want to run it at 2.7A it is designed to handle you will need a big heat-sink and even a Fan to dissipate the heat.
You will spend more than $4 on parts, but here is a $4 driver.
I dont need a driver . I want to make a cheap circuit (0.5$) that can produce 12v 300mA. I also make other circuits in cheap that can drive leds(In 0.5 $ only). But they cannot produce 300mA. So I need a circuit to drive them !
What supply have you got ?
You can't build a buck or boost circuit for 50c.
Buy one on eBay...
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Posted:Dec 31, 2015
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