Volts Linear
Volts Linear
Search through this page if you are looking for Volts Linear
 |
 WAC 12 Volts 6 LED Fixture For Linear System in White 4000K SBH 316 C WT  US $44.95
|
 WAC 12 Volts 4 LED Fixture For Linear System in Black 4000K SBH 314 C BK US $35.95
|
 WAC 12 Volts 6 LED Fixture For Linear System in Black 4000K SBH 316 C BK US $44.95
|
 Vaportite Two Light Multi Volt Linear Flush Mount in Light Gray VTL254HOMV US $192.60
|
 WAC 12 Volts 4 LED Fixture For Linear System in White 4000K SBH 314 C WT US $35.95
|
 WAC 24 Volts 6 LED Fixture For Linear System in Black 4000K SBH 316 24 C BK US $44.95
|
 WAC 24 Volts 4 LED Fixture For Linear System in Black 4000K SBH 314 24 C BK US $35.95
|
 WAC 24 Volts 6 LED Fixture For Linear System in White 4000K SBH 316 24 C WT US $44.95
|
 WAC 24 Volts 4 LED Fixture For Linear System in White 4000K SBH 314 24 C WT US $35.95
|
A question about calculating the optical output power of a LED?
I am working on a science fair project, and I need to calculate the Optical Output Power of a LED.
I know that the Optical output power of LED (watts) = N( a linear factor) × Voltage drop across resistor (volts)
Pout = N × Vres
* Pout is the optical output power in watts (W).
* N is a linear factor.
* Vres is the voltage drop across the resistor in the light-detection circuit in volts (V).
However, I am confused as to what N is. Any help would be appreciated.
I'm not sure where you got that equation, it doesn't look right to me.
Here's what you can do. First of all, go to the manufacturers or distributors website for the LED you are using, and search for the part number to get the datasheet (usually a pdf). Usually the voltage drop is approximately constant (higher voltage as you go through the rainbow). Also from the datasheet find an appropriate level of current. Next find a voltage supply (a battery is okay) that is higher than the LED voltage. Then calculate the value of the resistor you should use in series with the LED. This is the difference of the two voltages quantity divided by the current in amps. R = (Vs - V_LED)/I_LED
(where "I" denotes current).
The electrical power (in watts) going into the LED is the voltage across the LED (in volts) times the current (in amps).
When the circuit is connected, and the LED is lit, use a voltmeter to verify the LED voltage from the datasheet. To do this, place one meter probe on either side of the LED, and record the value. Next measure the voltage across the resistor, and record this value. To calculate the current through the LED, simply calculate the current through the resistor, since they are the same. The current equals the voltage across the resistor (in volts) divided by the value of the resistor (in ohms).
Next, from the datasheet get the "luminous efficacy" (in Lumens/watt or lm/W). Multiply this by the electrical power (in watts) we just calculated, to get the luminous output (in Lumens).
Next, read the paragraph at this link, and learn what you can from it, then click on the graph at right.
http://en.wikipedia.org/wiki/Luminous_efficacy#Luminous_efficacy_of_radiation
Find the LED's light wavelength (in nanometers or "nm") from the datasheet, then find this value on the bottom of the luminosity graph. http://en.wikipedia.org/wiki/File:CIE_1931_Luminosity.png
Draw a line up to the curve, and from there to the left axis. Read this value, that is the "luminous efficiency", and is between zero and one, and multiply this value by 100% to get a value between 0% and 100%.
Now you have the same values as listed in the table here under "examples": http://en.wikipedia.org/wiki/Luminous_efficacy#Luminous_efficacy_of_radiation
So you can compare your LED with other light sources.