LED's powered by by AC draw more current

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In summary: I built an array of 14 LED's the 20,000 mcd's ones maybe drawing 25 ma at 3.3 volts with each two LED's powered from 125 volts AC then to a .22 mfd capacitor in series feeding a full wave bridge rectifier so there are 7 capacitors and seven full wave bridges feeding all 14 LED's and they draw 6 watts power on AC and if you figure just the power consumption of 14 LED's at 25 ma on 3.3 volts they should only use a little over one watt is this an acceptable amount of current loss?In summary, the current consumption of the LED's should be around one watt, but this is only an acceptable amount of current loss if the wiring is safe and the LEDs are
  • #1
John1397
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I built an array of 14 LED's the 20,000 mcd's ones maybe drawing 25 ma at 3.3 volts with each two LED's powered from 125 volts AC then to a .22 mfd capacitor in series feeding a full wave bridge rectifier so there are 7 capacitors and seven full wave bridges feeding all 14 LED's and they draw 6 watts power on AC and if you figure just the power consumption of 14 LED's at 25 ma on 3.3 volts they should only use a little over one watt is this an acceptable amount of current loss?

John
 
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  • #2
John1397 said:
I built an array of 14 LED's the 20,000 mcd's ones maybe drawing 25 ma at 3.3 volts with each two LED's powered from 125 volts AC then to a .22 mfd capacitor in series feeding a full wave bridge rectifier so there are 7 capacitors and seven full wave bridges feeding all 14 LED's and they draw 6 watts power on AC and if you figure just the power consumption of 14 LED's at 25 ma on 3.3 volts they should only use a little over one watt is this an acceptable amount of current loss?
So this is a cheap and nasty method to power some LEDs for lighting, is it? Did you get the circuit from a publication, or is it your own plan?

Everything needs to be treated as though it is live at mains voltage, as indeed it only too easily can be. All wiring insulation and the LED mountings must be suitable for providing safety as though at 125VAC.

https://www.physicsforums.com/images/icons/icon2.gif How did you measure the 6 watts?
 
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  • #3
I seen this searching for ways to power LED's from AC it seemed easy has no transformer which wastes current to, but I see LED lamps that have 42 LED's and only draw 3 watts. I plan to switch them all to run off 12 volts DC so this will eliminate all the capacitors and diodes then I will be able to see how much current they draw.
 
  • #4
Using DC will make it simpler to measure the power, but won't much change the current the LEDs need for a particular intensity of output. You didn't answer:
How did you measure the 6 watts?
It may well be that your measurement technique is wrong.
 
  • #5
Used a digital power meter even plugged in a 7 watt Christmas bulb and showed 7 watts so I know it is right seems most of the leakage is is on all these diode bridges.

John
 

1. Why do LED's powered by AC draw more current compared to DC?

LED's powered by AC draw more current because AC power constantly changes direction, causing the current to alternate between positive and negative. LED's are diodes and can only allow current to flow in one direction, so they need additional components such as a bridge rectifier to convert AC to DC. This conversion process results in a higher current draw.

2. Is it safe to power LED's with AC?

Yes, it is safe to power LED's with AC as long as the proper components are used to convert the AC to DC. LED's can only handle DC current, so a bridge rectifier and a smoothing capacitor must be used to convert the AC to DC and provide a steady current to the LED's.

3. Can the higher current draw damage the LED's?

Yes, the higher current draw can potentially damage the LED's if the proper components are not used to convert the AC to DC. Without a bridge rectifier and a smoothing capacitor, the LED's will be exposed to constantly changing current, which can cause overheating and damage.

4. Are there any advantages to using AC to power LED's?

One advantage of using AC to power LED's is that it allows for dimming control and color changing capabilities. AC power can be easily controlled using a dimmer switch, allowing for adjustable brightness levels. Additionally, AC power can be used to create different frequencies, which can be used to change the color of LED's.

5. Can LED's be powered by AC without converting it to DC?

No, LED's cannot be powered by AC without converting it to DC. LED's require a constant flow of current in one direction, which can only be achieved by converting AC to DC. Attempting to power LED's with AC without proper conversion can result in damage or malfunction of the LED's.

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