uaefame
New Member
Hello everyone,
I started learning about LED, thing i learned are: not all LED have same forward voltage drop and it change according to current input.
For example Yellow LED 5mm has a voltage drop of 2.1V at 20mA at 1 intensity.
Q1> Is my calculation for selecting resistor for LED is true or wrong.
R=(5V-2.1V)/20mA=145ohms
I will select a near value resistor = 150ohms
Q2> I was wandering about the different and the use of these:
1- degree beam angle for IR LED
2- degree angle of half intensity for IR LED
I started learning about LED, thing i learned are: not all LED have same forward voltage drop and it change according to current input.
For example Yellow LED 5mm has a voltage drop of 2.1V at 20mA at 1 intensity.
Q1> Is my calculation for selecting resistor for LED is true or wrong.
R=(5V-2.1V)/20mA=145ohms
I will select a near value resistor = 150ohms
Q2> I was wandering about the different and the use of these:
1- degree beam angle for IR LED
2- degree angle of half intensity for IR LED