Power supply for 300 LED from AC

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janeceline

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I want to derive power supply for 330 LED's ( 6 rows of 55 LED's in series - Each LED 3.8v DC ). How to derive the circuit ? Any Idea ? Without transformers.
 
if for lighting you are better off using a lighting class LED than inefficient 5mm parts. What is it you want to accomplish?
 
to eliminate 40w flouracent tube

i want to use it for home lighting instead of 40W flouracent lamp. what do u mean by lighting class LED ? Where we can get it ? I have only 5mm LED with 3.9V DC rating.
 
40W flourescent or 40W incandescent replacement (which is actually only around a 10W fourescent)? The incandescent is only going to put out 400-500Lm but much of it is lost to the reflector and the rest of the room instead of going toward your work surface.

Your 330 LEDs will put out 300Lm, if you are lucky, using 25W to do so. 3 **broken link removed** driven by **broken link removed** will put out 240Lm for 3W
 
40W flouracent tubelight

its 40W flouracent tubelight. i want circuit diagram to derive the power supply for 330 LED's from 220V ac direct without transformer. Any idea ?
 
the 40W tube will put out 2500Lm of which about half is actually reaching your work surface. You might get away with 600Lm from LEDs for a comparable amount of light on your work surface, but that is 600-1200 or more of your little LEDs or 6 of the ones I reccommended. Two of the drivers I recommended is still less expensive than building one yourself.
 
But i want to doit myself

i want to do it myself the power supply. i want to know the circuit diagram for that. please help
 
janeceline said:
i want to do it myself the power supply. i want to know the circuit diagram for that. please help
Click to expand...

Hi there Jane,

We were talking about an LED circuit the other day that runs off of
220vac mains. It's here on this forum somewhere. It uses a capacitor
and a bridge rectifier to run a string of LEDs. It does not require
a transformer. To run that many LEDs you would use a few separate
strings all driven the same way. Sound interesting?
 

Won't it work if 230VAC is directly given through a series resistor with out rectifier and capacitor?
 
premkumar9 said:
Why? In one half of the AC the LEDs will glow and in the other half 55 LEDs will remain reverse biased. 55 LEDs in series must be able to withstand this reverse voltage. Is it not?
Click to expand...
Well I did not see about the reversed ones, but that is beside the point. Unless there is a bleeder resistor across each and every LED differing leakage currents will cause them to blow since they will not share the voltage equally.

another way around that is to have a single string with anti parallel LEDs all the way up instead of anti parallel strings... or is that what you meant?
 
Last edited:
janeceline said:
i want to do it myself the power supply. i want to know the circuit diagram for that. please help
Click to expand...


Be safe. Do it with an isolation transformer if it is powered by mains. Better yet, buy a compliant DC power supply to power your low voltage circuit.
 
Ubergeek63 said:
Well I did not see about the reversed ones, but that is beside the point. Unless there is a bleeder resistor across each and every LED differing leakage currents will cause them to blow since they will not share the voltage equally.
Click to expand...

Instead of these theoretical discussions it would be better if somebody try 3 of these diodes(Vf 3.8V) in series with a series resistor, say 56Ω ,and connect it to 12 V AC of the secondary of a transformer.

For high voltage rectification diodes are connected in series with out any parallel resistor. In the case of high voltage rectification for TV (25 KV) so many diodes are connected in series. Some one may please correct me if I am wrong.
 
Optikon said:
Be safe. Do it with an isolation transformer if it is powered by mains. Better yet, buy a compliant DC power supply to power your low voltage circuit.
Click to expand...

I think, the requirement here is to make an LED lamp for room lighting working at 230V AC which can replace the conventional bulbs. So using a transformer, power supply etc may not be practical. Right?

This is a product available in the market and you can just see if it has got transformer, filter etc.
 
A single red or green pilot LED requires only an 56K resistor across 230V. Normal LEDs have low brightness otherwise a bright type must be used. A diode resistance combination can be used for getting good brightness. Here resistance must be atleast 2W type.
 
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