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check if the value of the resistor R5 protecting the blue led is correct
jmrod

jmrod

@copilot check if the value of the resistor R5 protecting the blue led is correct
2y

copilot

To check if the resistor ( R5 ) value of 180 ohms protecting the blue LED is correct, we'll use the following information:
  1. The forward voltage of the blue LED. Since no specific information is provided, I'll assume a typical forward voltage for a blue LED, which is generally around $ V_f = 3.0 , V $.
  2. The desired current through the LED. A common typical current for standard LEDs is around 20 mA ($ I_f = 20 , mA $).
  3. The supply voltage, which we assume to be 3.3V based on the project components.
Using Ohm's law, the resistor value can be calculated by:
R=Vsupply−VfIfR = \frac{V_{supply} - V_f}{I_f}
Given:
  • $ V_{supply} = 3.3 , V $
  • $ V_f = 3.0 , V $
  • $ I_f = 20 , mA = 0.02 , A $
Let's plug these values into the equation:
R=3.3 V−3.0 V0.02 A=0.3 V0.02 A=15 ΩR = \frac{3.3 \, V - 3.0 \, V}{0.02 \, A} = \frac{0.3 \, V}{0.02 \, A} = 15 \, \Omega
So, the required resistor value should be around 15 ohms for a typical blue LED. Since the provided resistor value is 180 ohms, we can calculate the actual current through the LED using Ohm's law again:
If=Vsupply−VfR=3.3 V−3.0 V180 Ω=0.3 V180 Ω≈1.67 mAI_f = \frac{V_{supply} - V_f}{R} = \frac{3.3 \, V - 3.0 \, V}{180 \, \Omega} = \frac{0.3 \, V}{180 \, \Omega} \approx 1.67 \, mA
This indicates that with a 180 ohm resistor, the current through the LED will be approximately 1.67 mA, which is much lower than the typical 20 mA. This current is safe for the LED, but it will not be very bright.
Conclusion: If you want a brighter LED, you might consider lowering the resistor value closer to 15 ohms, but for a low-brightness application, 180 ohms will work without damaging the LED. Adjust the resistor value based on your brightness requirements.
2y
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J40
SW1
SW7
N_CLK
IN_3
LED_KO
SW3
IN_5
SW2
LED_KO
LED_BLEUE
N_SCL
IN_2
IN_0
N_SDA
N_SDA
LED_BLEUE
IN_6
N_SW
IN_4
IN_7
IN_0
N_DT
SW4
IN_7
N_GND
LED_OK
SW6
IN_5
LED_OK
IN_6
N_SCL
IN_1
IN_3
IN_2
IN_1
IN_4
SW5
N_GND
N_CLK
SW8
N_DT
D8
5V
R10
Resistance
10KΩ
5V
J42
D7
R4
Resistance
15 Ω
3.3V
D5
D6
5V
3.3V
3.3V
R7
Resistance
15 Ω
3.3V
R6
Resistance
15 Ω
3.3V
R3
Resistance
15 Ω
J2
R2
Resistance
15 Ω
5V
D1
3.3V
R8
Resistance
15 Ω
D2
5V
3.3V
J41
3.3V
R9
Resistance
10KΩ
J1
D3
R5
Resistance
15 Ω
R1
Resistance
15 Ω
3.3V
3.3V
D4
J39
J43
M2
M1
M4
M3
SW9

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