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Super LED Light 60LEDs@3.2V & 20mA on 9Volts

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Dulimir

Dulimir

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Hello,

Ive just joined up today so this is my first post. Ive done some stuff with electronics in highschool but that was a long time ago, so im having some truble.
Here is what im working on:
photo.JPG
As you can see i have room for 60 LEDs. I want to use White LEDs that run at 3.2V and consume 20mA, and i want to run it all from a single or dual 9v standard battery pack (for example Duracell PP3). I was thinking i should connect the LEDs in 20 series of 3. People say it works, but im not sure how, as 3x3.2V is more than 9v (9.6V), and im not sure if i would need a resistor that way, would the LEDs be as bright as they should etc...
Ive also read about a thing called LM317, some kind of regulator... im clueless.

Any help would be greatly apreciated!

Cheers!
 

Please go to this thread I post there some nice circuit:

https://www.edaboard.com/threads/228925/

Also consider of working time on 9V battery. Calc battery capacity and nominal manufacturer discharging period of time and current. Also calc and consider voltage booster efficiency.

I suggest to always use stabilization of current in LED circuit.
 
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hmm, im trying to grasp the connection....

as for the capacity, together, the diodes dissipate 3840 mW
total power dissipated by the array is 5640 mW
the array draws current of 600 mA from the source.

that was done using a calculator **broken link removed**

i have limited space as the unit needs to be portable and as light as possible, using 3 9v batterieswould be the maximum. so that would give me a source of about 1650mA, as the standard 9v is 550mA, i think.
 

Nuclear Plant :lol:

Lets look:

How many diodes You whant to run ?
What is their voltage and current?

You say power source to be 2x9V or 1x9V alkaline or lithium ?
Rechargable or Alkaline or Lithium ?

Lithium 9V
1200mAh

Alkaline 9V
500mAh

NiMh Rechargable 9V
160mAh


Typical max drain for alkaline 9V battery is 15mA (for manufacturer capacity)
 
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photo2.JPG
In this box i will harness the power of the atom, or maybe i could create a tiny black hole and use its powerfull magnetic field to generate a current to power my 60 LEDs :p lol
 

I think that You have small box for power of atom. :lol:

Ok lets see:

60 LED
3,2V
20mA


This is raw calc:

If You use 2x9V alkaline in serie You will get 18V with 500mAh.

18V / 3,2V = 5 LED in serie with resistor 100R. 5 LED in serie dissipate 16V and resistor will have 2V.

Then:

Battery capacity is 500mAh. 500mAh / 20mAh (One serie of 5 LED) = 25h working hours (consider nominal current drain for this battery is 15mA).

If You use 60 LED in 12 series with 5 LED in each serie. You get following : 12 x 20mA = 240mA total current drain.

For Lithium 9V 1200mAh is 1200mAh / 240mA = 5h.
 
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im going to use these, i dont know how many though!
9 V Block
Lithium 1200 mAh
 

I dont have a picture to put it there, I make for my car "hell of light" I put 200 highbright LED in each front car light. Each LED is 25cd (25000mcd) and used in two car light (400 LEDs), other two is standard halogen.

Total 10.000.000mcd

It make sunlight at night. :cool:
 
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After doing some more research, i found that i have to connect 2 led's and a 150 Ohm reseistor to each parallel series. This is alot of soldering, and im not sure i have the skill to make it well enough that way, so i would like some confirmation on that, or any advice!
Cheers!
 

Dulimir said:
After doing some more research, i found that i have to connect 2 led's and a 150 Ohm reseistor to each parallel series. This is alot of soldering, and im not sure i have the skill to make it well enough that way, so i would like some confirmation on that, or any advice!
Cheers!
Click to expand...


Thats not good. You will get in each array current of 20mAh (with two diodes), and for 60 LED its 30 arrays with consuption of current about 600mA, its a lot for battery of that size. 600mA current is job for lithium or lead acid 4,6,7Ah...

Better use some voltage doubler or led switcher driver, but consider efficiency and waste power needed for voltage boost. If You need circuits say.
 

Well, my calculations tell me that it should work for about 1hour and 20 minutes :) thats more than enough, as the light will be used minutes at a time. Ive considered boosting the voltage, but i would need alot more equipment and then i face alot of heat in a small closed container, yada yada, itreally complicates things for me. I have to get my LED's so that i can test them out, to see how bright they are, i might need less than 60, then i might wire it in 2 arrays of 30 and have 4 9v 1200mAh , 2 for each array with seperate switches to have like 2 stages of brightness. I can post a pic of the housing i am using, but i already posted a pic of the top cover on which the led's will be mounted. im open to all suggestions, but the housing has to stay the same.
 
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Dulimir said:
Well, my calculations tell me that it should work for about 1hour and 20 minutes :) thats more than enough, as the light will be used minutes at a time. Ive considered boosting the voltage, but i would need alot more equipment and then i face alot of heat in a small closed container, yada yada, itreally complicates things for me. I have to get my LED's so that i can test them out, to see how bright they are, i might need less than 60, then i might wire it in 2 arrays of 30 and have 4 9v 1200mAh , 2 for each array with seperate switches to have like 2 stages of brightness. I can post a pic of the housing i am using, but i already posted a pic of the top cover on which the led's will be mounted. im open to all suggestions, but the housing has to stay the same.
Click to expand...


1. DC/DC voltage booster can be small and need few components!

2. Lithium 9V Battery capacity 1200mAh have nominal voltage 9,6V also consider nominal draining current!!!!!! Time discharging curve not linear!!!!!!!
 

Hmm. So no matter how many LED's i put in series, every series has 20mA, so if i boost the voltage, i can have 1 series ?
Im sorry if its a stupid quiestion...

where can i find instructions to build this DC/DC voltage booster?


ps: tek sad sam shvatio da si iz srbije lol...
 

Dulimir said:
Hmm. So no matter how many LED's i put in series, every series has 20mA, so if i boost the voltage, i can have 1 series ?
Im sorry if its a stupid quiestion...

where can i find instructions to build this DC/DC voltage booster?


ps: tek sad sam shvatio da si iz srbije lol...
Click to expand...


RAW flat Example :

If we use two batteries in serie it give us 18V. LED is on 3,2V at 20mA. Then 18V/3,2V=5 led in one array. 5 led x 3,2V = 16V, and 2V must be dissipate with resistor. Resistor will be 100R.
Thise give us 5 LED in serie with total current consuption of 20mA.

If we use one battery 9V. Then 9V/3,2V=2 led in one array. 2 led x 3,2V = 6,4V and 2,6V must be dissipate over 150R resistor. This scenario give 2LED in serie with total current consuption of 20mA.

We whant to use total number of 30 leds on 18V, then 30/5 = 6 serie array x 20mA = 120mA total.
We whant to use total number of 30 leds on 9V, then 30/5 = 15 serie array x 20mA = 300mA total.


ps: pa što nereče bre polomismo se preko ovog engleskog
 

So if im getting this right, if i can somehow turn my 9 volts into 192 volts, i can have all 60 leds in one serie using only 20 mA ? Can i do that? lol
 

Dulimir said:
So if im getting this right, if i can somehow turn my 9 volts into 192 volts, i can have all 60 leds in one serie using only 20 mA ? Can i do that? lol
Click to expand...


Yes something like this calc, but must use datasheet of manufacturer to see what is breakdown voltage for that led diode.
 

What is breakdown voltage ?
 

ahh :) poof :) lol

wow, those schematics look complicated, im not sure i can handle that as a first project:O
 

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