Hello,
I just started learning electronics and for my first setup, I built the classic setup: resistor + LED.
I choosed a red LED and this is the datasheet:
As I understand it the important parts are: If = 20mA and Vf = 2V.
Then I calculated the resistance I needed with a formula I've seen a lot on internet : R = (Vsupply - Vled) / I
I use a 3.3V raspberry py pin for my supply so have : R = (3.3 - 2) / 0.020 = 1.3/0.020 = 65 Ohm.
I should use a 65 Ohm resistance but I don't have one, so I used a 100 Ohm resistance.
Here is the complete setup:
But when I measure the differents value, here is what I have:
Current in the circuit: 7.2mA
Voltage drop across the LED: 2.53V
So in reality the tension applied to my LED is too high and could damage it but it is consuming less current that announced in the datasheet.
I really don't understand where i screwed up in my calculations, someone could help me figure out why the setup behave like this ?
I just started learning electronics and for my first setup, I built the classic setup: resistor + LED.
I choosed a red LED and this is the datasheet:
As I understand it the important parts are: If = 20mA and Vf = 2V.
Then I calculated the resistance I needed with a formula I've seen a lot on internet : R = (Vsupply - Vled) / I
I use a 3.3V raspberry py pin for my supply so have : R = (3.3 - 2) / 0.020 = 1.3/0.020 = 65 Ohm.
I should use a 65 Ohm resistance but I don't have one, so I used a 100 Ohm resistance.
Here is the complete setup:
But when I measure the differents value, here is what I have:
Current in the circuit: 7.2mA
Voltage drop across the LED: 2.53V
So in reality the tension applied to my LED is too high and could damage it but it is consuming less current that announced in the datasheet.
I really don't understand where i screwed up in my calculations, someone could help me figure out why the setup behave like this ?