What is best way to operate 95 Bright Green LED in parallel

[Sheeraz Khan]

What is best way to operate 95 Bright Green LED in parallel on 4.8 Volts ?

thanks
Sheeraz Khan

 

[laktronics]

Re: What is best way to operate 95 Bright Green LED in paral

Hi,
Depending on the forward voltage drop (which you can measure and find out), I suppose, you can connect three to four in series with a small current limiting reistor and such 32/24 connections in parallel to 4.8V.
Regards,
Laktronics

 

[manish12]

Re: What is best way to operate 95 Bright Green LED in paral

try this you probably get sufficient brightness ,

 

[mrcube_ns]

Re: What is best way to operate 95 Bright Green LED in paral

Hi Sheeraz Khan,

This should be only way on 4.8V, to get all leds ON.

You don't specify operating current of LEDs, so there are 2 standard currents 20mA and low current 2mA. On picture you can see 2 values for resistors regarding to possible leds current: 140 Ohm is for 20mA, 1k4 is for 2mA. This values I get very easily, leds have around 2 volts on pins when working so reast 2.8V I divide with 2/20mA and that's it.


Regards,
Mr.Cube

 

[xorcise]

Re: What is best way to operate 95 Bright Green LED in paral

YES... connect 95 GREEN LED's only in parallel... with a 4.8V power supply.

You will only need a Single Resistor in series with 1 leg (doesn't matter which leg) of the 4.8V supply to the 95 paralleled LED's. GREEN LED's vary from to 2.5V to 3V forward drop under loading... around 10-20ma, and that same voltage drop is across the whole parallel configuration. So, the single supply side series R must drop ~2V at the desired TOTAL current.

Assume that you would like 10ma per LED. For 95 LED's that will require a power supply of 4.8V @ 950ma (very close to 1 amp). The series R must drop 2V at 1 amp. A little Ohm's Law and the Series R should be 2 Ohms (2V/1A).

The kicker is the wattage of this resistor (E*I) = 2x1 = 2 Watts. That's fairly easy to find.

NOTE: You should not series any of the LED's since your power supply cannot furnish the voltage required (~5-6V) under load. Also, you do not need any series R with each LED, since the supply current is distributed evenly in the parallel array and is limited by the single supply side resistor.

All LED's will be on and even brightness in a very simple circuit of 1 resistor and 95 LED's.

**broken link removed**

You can buy 5V (built-in current limiting) Green LED's from the electronics supply houses... then you only need a 4.8V power supply of sufficient current to run that many LED's:

**broken link removed**

 

[watermelon]

Re: What is best way to operate 95 Bright Green LED in paral

I guess, the practice of using ONE RESISTOR for all LEDs is not recommended. Let us assume that one of the LEDs turns on at 2.7V and other turn on at 2.75V.
This one LED will now hog most of the current and burn out. This will continue till there are LEDs with different turn on voltages.
It is best to keep each LED (or a set of series connected LEDs) with a separate resistor to ensure that any differences in current and voltage are taken care of by the resistors connected to the LEDs.
Best of luck.