Help and information needed on a Resistor value - Electronic Circuits Projects Diagrams Free

Eralyn · 13th March 2008, 06:40 PM

I wish to wire a super bright flashing 10mm LED to a circuit on my car, the battery supplies 12 volts the However I need to know what value of Resistor I need to enable me to do this. The specification for the led bought from Maplin is http://www.maplin.co.uk/module.aspx?ITAG=SPEC&ModuleNo=35843&doy=13m3#spec

Super Bright Diffused Red 0.5V
Kingbright description: L-816BSRD-B
Forward voltage: 2.5V
Forward current max.: 55mA
Reverse voltage max.: 0.5V
Wavelength @ peak : 660nm
Power dissipation PT: 310mW
Light output min.@ 9V: 100mcd
Light output typ.@ 9V: 300mcd
Can any body please advise me as to the type of Resistor needed for this type of LED to enable me to connect to a circuit powered by a 12 volt car battery?

Cry_Wolf · 14th March 2008, 12:05 AM

As you mentioned a circuit i would suggest you to use a regulator. Using simply a resistor may not be that efficient

Cry_Wolf · 14th March 2008, 12:07 AM

Or may be a voltage divider followed by an appropriate zener...

Not sure.. Waiting for correction

Holger · 14th March 2008, 01:05 AM

Hello ...try to use a resistor 220 ohms 1 W..it will do it..calculated at max 13,8 V and abt 50mA......a 0.7 W will suffice because it's no continuos load...it's flashing....Good luck....Holger

Eralyn · 15th March 2008, 01:02 PM

All I want to do is wire the led to a 12 volt battery source without frying the led. so all Ineed is a resistor, but do not know the value of the resistor to use. I think the type of resistor i need is carbon film reistor.. the type that has coloured bands around.

ericgibbs · 15th March 2008, 01:22 PM

Quote:

Originally Posted by Eralyn

All I want to do is wire the led to a 12 volt battery source without frying the led. so all Ineed is a resistor, but do not know the value of the resistor to use. I think the type of resistor i need is carbon film reistor.. the type that has coloured bands around.

As you buy from Maplins, look at this 2W range, use a 270R to allow for a vehicle charging voltage of 14.8v.

Resistor = (14.8v - 2.5v)/0.045A = 270R

If you can find a 1Watt version that would be OK.

http://www.maplin.co.uk/module.aspx?...&doy=15m3#spec

Eralyn · 15th March 2008, 02:00 PM

Quote:

Originally Posted by ericgibbs

As you buy from Maplins, look at this 2W range, use a 270R to allow for a vehicle charging voltage of 14.8v.

Resistor = (14.8v - 2.5v)/0.045A = 270R

If you can find a 1Watt version that would be OK.

http://www.maplin.co.uk/module.aspx?...&doy=15m3#spec

Thank you very much for your advice it is very much appreciated.

ericgibbs · 16th March 2008, 08:46 AM

Quote:

Originally Posted by Eralyn

Thank you very much for your advice it is very much appreciated.

Hi,
Check the LED flasher datasheet, it operates from 3.5V thru 14V, suggests NO series resistor is required for a vehicle [12V] application.

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13th March 2008, 06:40 PM	(permalink)
Eralyn	Help and information needed on a Resistor value I wish to wire a super bright flashing 10mm LED to a circuit on my car, the battery supplies 12 volts the However I need to know what value of Resistor I need to enable me to do this. The specification for the led bought from Maplin is http://www.maplin.co.uk/module.aspx?ITAG=SPEC&ModuleNo=35843&doy=13m3#spec Super Bright Diffused Red 0.5V Kingbright description: L-816BSRD-B Forward voltage: 2.5V Forward current max.: 55mA Reverse voltage max.: 0.5V Wavelength @ peak : 660nm Power dissipation PT: 310mW Light output min.@ 9V: 100mcd Light output typ.@ 9V: 300mcd Can any body please advise me as to the type of Resistor needed for this type of LED to enable me to connect to a circuit powered by a 12 volt car battery?

14th March 2008, 12:05 AM	(permalink)
Cry_Wolf	As you mentioned a circuit i would suggest you to use a regulator. Using simply a resistor may not be that efficient __________________ Khizer Naeem Mughal IIUI

14th March 2008, 12:07 AM	(permalink)
Cry_Wolf	Or may be a voltage divider followed by an appropriate zener... Not sure.. Waiting for correction __________________ Khizer Naeem Mughal IIUI

14th March 2008, 01:05 AM	(permalink)
Holger	keep it simple Hello ...try to use a resistor 220 ohms 1 W..it will do it..calculated at max 13,8 V and abt 50mA......a 0.7 W will suffice because it's no continuos load...it's flashing....Good luck....Holger

15th March 2008, 01:02 PM	(permalink)
Eralyn	All I want to do is wire the led to a 12 volt battery source without frying the led. so all Ineed is a resistor, but do not know the value of the resistor to use. I think the type of resistor i need is carbon film reistor.. the type that has coloured bands around.