Power Supply for 22 LED's

[josephjk]

I want to lit up 22 white normal LED's; I need a transformer less power supply for that should I connect the LED's in serial or Parallel. Please help me. I am new bee to electronics.

 

[k7elp60]

josephjk, If you tell us the colors of the LED's and the quantity of each color we can help you. Also you say a transformer less powersupply are you talking about a battery or a plug in lines adapter?

 

[Ian Rogers]

k7elp60! 22 white normal LED's... if you need to run them at full brightness you need @ 25 - 30mA each.. 550mA to 660mA in total. (assume 3v per LED) In parallel 3v @ 660mA. In series 66 volts @ 30mA,

Or 12v @ 120mA x 5 (I know that's only 20) for 5 sets of 4 in series.

Which way do you want to go.

 

[ronv]

AC Leds

I think this is what you are looking for.
The capacitor needs to be what they call across the line rated for 600 volts, the resistor needs to be 1/2 watt. I didn't draw all the diodes, but 11 go in one direction in series and the other 11 go in series in the other direction. Be careful!

 

[carbonzit]

Ronv: while that might work, I wouldn't go jumping to conclusions. The O.P. said they wanted a "transformer less power supply": that doesn't necessarily mean they want to connect the LEDs directly to the power line, since they did say "power supply".

So let me ask you, the O.P. (original poster): what exactly do you mean by that? Do you want a power supply that doesn't use a transformer (like a switch-mode power supply, although most of these do use transformers)? Do you want to plug this directly into the wall socket without any kind of power supply? Something else?

 

[josephjk]

Actually i used 3V white leds 22of them connected in parallel and i used 9V 1A DC I used 240v to 18v 1 a transformers with diodes capacitors and i used IC 7809 to regulate it.

First time it worked, now it is not working.
I saw in many circuits which uses capacitors and 1/2w resistors to power up this type lights. (PLZ SEE THE ATTACHMENT)

my transformer with the circuit is a huge one to carry around. so i need a light weight system

 

[cowana]

Am I right in thinking you had all 22 LEDs connected in parallel driven off one 7905? That's what your post sounds like.

If there was no resistor, that means you have 9v directly across every LED - they would burn out very quickly. Even if you include a resistor, it isn't a good idea to have them all in parallel, as manufacturing differences will cause some to draw more current than others. Keeping them in series is a much better idea.

A

 

[colin55]

The .pdf above has a number of mistakes. See my website <snip: spam> under "Spot the Mistake" - page about 9,10 or 11. I contacted Chopra and the writer of the article but no reply. Nearly all the projects in EFY have mistakes.
The Indians have absolutely no idea how to design a circuit.

 

[ronv]

Post #4 is a simplified version of your attachment. It will supply 15 ma for your leds.

 

[carbonzit]

The .pdf above has a number of mistakes. See my website <snip: spam> under "Spot the Mistake" - page about 9,10 or 11. I contacted Chopra and the writer of the article but no reply. Nearly all the projects in EFY have mistakes.
The Indians have absolutely no idea how to design a circuit.

Colin, I think it would be a bit more accurate to say "Those particular Indians have absolutely no idea how to design a circuit". Certainly those bad sites (and they are bad!) shouldn't reflect upon the entire population of Indian engineers.