Merlin3189 said:If the LED is in series with the resistance, then the pd across the LED + the pd across the R add up to the supply voltage U.
If you have the u-I graph for the LED, you can plot the u-I graph for the R (which is just a straight line, U=IR) backwards starting from u=U. Where the two graphs cross, the current is the same in both elements (series circuit) and the voltages across them add up to U. This is the operating point. Look up "load line" for more info.
Unless U or I is varying, which it normally isn't for R-LED circuit, then the capacitor is irrelevant. It is probably there to smooth ripple on U.
Draw the resistor load line on a copy of the LED's graph.Themadflower said:But i don't have a function, only the Graph. Should i try to find one for the LED?
Yes, use the LED’s characteristic curve. Its equivalent resistance changes with the current.Themadflower said:But i have another question, how can i determine the series resistance of My LED? Only with the Characteristic curve ?
You can't safely power a device until you know its current capability! Surely its graph indicates its working current and voltage values?Themadflower said:Oh i mean the Series resistance i need for My LED. i don't Know the maximum current
If you are designing a new circuit then you consult the LED manufacturer's spec sheet; if you are repairing a circuit board, then the local supply voltage and the LED’s color and its series resistor allow you to estimate the current it has been using.Themadflower said:Okay Thats nice but is there a Way to Know the Working current ?
Is this a construction project and you have actual parts on hand, or a theoretical exercise?Themadflower said:Okay i have a voltage supply of 5v and a Blue LED. How can i make estimations?
Earlier I thought you said that you do have its characteristic graph?Themadflower said:Okay i have a voltage supply of 5v and a Blue LED. How can i make estimations?
An LED (Light Emitting Diode) is a semiconductor device that converts electrical energy into light. It is commonly used in electronic devices as a source of light.
The characteristics of an LED include low power consumption, high durability, small size, and fast switching speed. It also emits a narrow wavelength of light, making it useful for specific applications.
To find the current in an LED circuit, you can use Ohm's Law (I = V/R), where I is the current, V is the voltage, and R is the resistance. The voltage drop across an LED is typically between 1.8-2.2 volts. Therefore, you can calculate the current by dividing the voltage by the resistance of the circuit. The voltage can be found using a multimeter.
The current and voltage in an LED circuit can be affected by the resistance of the circuit, the properties of the LED, and the power supply used. If the resistance is too high, the current may be too low for the LED to light up. The properties of the LED, such as its forward voltage and maximum current rating, also play a role in determining the current and voltage. Additionally, using a power supply with a higher or lower voltage can affect the current and voltage in the circuit.
To ensure the LED is properly connected in the circuit, you can use a multimeter to test the voltage and current at different points in the circuit. The voltage drop across the LED should be within the specified range, and the current should be high enough for the LED to light up. You can also check the polarity of the LED to make sure it is connected in the correct direction, as LEDs are polarized and will not work if connected incorrectly.