LEDs in series

What's so difficult about connecting LEDs in series?

Just connect them in series remembering to connect anode to cathode.

Hi,

Thanks for prompt reply.

I still do not understand as how LED will gie light in series, because current will not pass from anode to cathod, only first one LED will give light next one will not get the current as anode is connected to cathod, and so will not glow.

I am cofused, please explain.

DPParkhe

Oh, do remember the series resistor to limit the current....

Hello dpparkhe

If using LED's in Series, then ensure all the LED's are of the same type, colour, and current rating.

If these above vary, one LED's may receive a higher voltage across itself than others, and thus may burn out.

Kind Regards....

Some of the better LED distributors have online calculators that allow for series, parallel or a mixture of both circuits and allow you to impute the LED values which, contrary to what was said earlier, can be mixed and matched. They then allow you to solve for resistance or voltage.

No need to reinvent the wheel or get an advanced degree in "geranium diodies"!

L. J.

I thank you all of you,Vulcan,Ozzb,Lsprab,Sparkstation and Lj, who have given me the directions to connect LED in series.You have given me help without any reservations , even though my question may apper silly to you,that is the real spirit to help, you are all great.

I think,my problem was of academic nature and have not done the connections myself and seen practically what happens. It is my ignorance and mistake and I feel sorry for it, to bother you all.

Can you suggest me some book to study all about LEDs,so that I will not ask such questions again.

I have connected 4 bluish white LEDs in series and seen that, with 9 volt battery, it is not giving sufficient light which I wanted, but when connected in parallel they have given quite bright light,

If you do not not mind I have 3 more questions:-

My first question is how to get the same bright light ,when connected in series.How much input of DC current, voltage and resistance I should use to get the bright light like I got by connecting 4 LEDs in parallel, and what are advantages and disadvantages of both connections.

Second question is:- What are the values of current[ inMilli Ampere] in common, AA,AAA,C, D,[all 1.5 volts]and 9 volt dry batteries, I tried to find out on Google but could not get the correct values, if you can help me by giving the site, or values,it will be great.

Third question is:- Is there a voltage cum current regulator chip for such small values, if so, which chip I should use and according to which formula,

Sorry to bother you again.

D.P.Parkhe

Hello again, dpparkhe

It's quite OK to ask questions here, we all started by asking questions, and it is really no bother to us.

The only truly ignorant person is the person who never asks any questions, in case others think he is ignorant, and so he remains ignorant.

Warning: Running any LED directly from a 9 Volt battery will damage the LED because of overcurrent.

All LED's are made with a "Type Number", then have their Operating Voltage and recommended currents published.

Because you have not stated the Maker's name and LED actual type, any figures would be guesses at best.

You must have bought the LED's from a supplier, and that supplier should be able to give you the make & type number of the LED's.

From those the tables can be consulted, and the LED circuitry arranged so as the LED's are operated at the designed voltage/Current, for long life.

Currents from dry cells/batteries:

These vary, unfortunately, even amongst the same Maker, who may make several different styles of the same dry cell, for use in different purposes.

White LED's in use:

Please refer to: http://www.maxim-ic.com/appnotes.cfm/appnote_number/3014

There you should read about white LED's, and see some circuits which may be useful for you.

Continue to learn, and enjoy each new day as it arrives.

Don't forget to

Kind Regards....

When you connect LEDs in series, they divide the voltage from the battery among themselves. Four LEDs in series connected to a 9 volt battery, therefore, will have 9 ÷ 4 = 2.25 volts across each LED. That's assuming that the battery is really putting out 9 volts.

2.25 volts seems sufficient but you should also know that LEDs need sufficient current in order to light up. Connecting LEDs in series decreases this current resulting in the dim light you got.

By connecting the LEDs in parallel, you put 9 volts across each LED. 9 volts, as far as I know, is too much! That will explain the bright light you got but be aware that your LEDs will not last very long.

A typical LED circuit has a resistor in series with the LED. You can use experimentation to obtain the correct resistor for your particular LED:

1. Get a 5kΩ potentiometer, a 9 volt power supply and some wires. Set the potentiometer at maximum resistance and connect one LED in series with the potentiometer and power supply.
2. Slowly decrease the potentiometer resistance until you get sufficient brightness from your LED.
3. Disconnect the potentiometer and measure the resistance. This will be the value of the series resistor you will need to connect to each LED.

Note: Determining if the brightness is sufficient is going to be up to you. If the LED is getting hot, you've exceeded the LED's current rating. You may even have damaged it. That's the risk you take when experimenting this way.

Thank you very much for giving very good information.

I will be now able to design the product which I want by your guidance.

If there is any difficulty or problem ,I will get back to you.

With Warm Regards,

DPP

Hi,

I am very much obliged to everybody who have helped me to solve my problem.

Thank you very much for giving very good information.

I will be now able to design the product which I want, with your guidance.

If there is any difficulty or problem ,I will get back to you.

With Warm Regards,

DPP