LED Resistors - table and excel worksheet | O Gauge Railroading On Line Forum

MEDOGR Forum Member

For what it is worth, I created an Excel worksheet that shows the 5% resistor values for LEDs. Includes different color LEDs, and different supply voltages. I took the calculated resistor values and picked the closest, but higher rather than lower, standard available 5% resistor.

Calculations using lowest Vf (forward Voltage drop), and max operational current of 20ma. I looked just a few LED datasheets, and 20ma was the max operational current. Peak currents ranged from 30 to 100ma, and many definitions of duty cycle for this peak current. However, the LEDs I looked at would all easily tolerate the 60Hz AC we use, the If peak being 28ma.

While the attached pic of the table is static, the attached Excel 2007 worksheet has cells below the table where you can enter your own values of Supply, Vf, and If, and it will calculate the Resistor.

For reference, I got the resistor standard values from this website

https://eepower.com/resistor-g...es/resistor-values/#

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LED Resistor Chart.xlsx

1/31/212:15 PM

Original Post

H1000OGR Forum Member SUPPORTING MEMBERDIGITAL SUBSCRIBER

Check this site out. It will also calculate resistance values when using Multiple LEDs in series or parallel.

There are also lots of APPS for your smart phone that can also do this for you on the fly.

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