Table of Contents
- 1 How do I calculate what resistor I need?
- 2 How do you calculate resistors in a circuit?
- 3 What resistor do I need for a blue LED?
- 4 How do I determine the wattage of a resistor?
- 5 What resistor do I need to drop 12V to 6v?
- 6 Do 12V LEDS need resistors?
- 7 How do you calculate the resistance of a 12 volt resistor?
- 8 How do you calculate the resistor value for LED lights?
- 9 How do you find the value of a resistor in parallel?
How do I calculate what resistor I need?
We’ll use the following formula to determine the resistor value: Resistor = (Battery Voltage – LED voltage) / desired LED current. For a typical white LED that requires 10mA, powered by 12V the values are: (12-3.4)/. 010=860 ohms. To use several LEDs in parallel, sum the current values.
How do you calculate resistors in a circuit?
If you know the total current and the voltage across the whole circuit, you can find the total resistance using Ohm’s Law: R = V / I. For example, a parallel circuit has a voltage of 9 volts and total current of 3 amps. The total resistance RT = 9 volts / 3 amps = 3 Ω.
What resistor do I need to drop 12V to 9V?
To reduce a 12V circuit to 9V, place two resistors in series within the circuit. Find the difference between the two voltages (12V – 9V = 3V) to determine the total amount of resistance needed.
What resistor do I need for a blue LED?
290 ohms
LEDs typically require 10 to 20mA, the datasheet for the LED will detail this along with the forward voltage drop. For example an ultra bright blue LED with a 9V battery has a forward voltage of 3.2V and typical current of 20mA. So the resistor needs to be 290 ohms or as close as is available.
How do I determine the wattage of a resistor?
What is the maximum power rating in watts of a fixed resistor which has a voltage of 12 volts across its terminals and a current of 50 milliamperes flowing through it. Given that we know the values of the voltage and current above, we can substitute these values into the following equation: P = V*I.
How do you find resistance with power and voltage?
For example if the power is 100 watts and the voltage is 50 volts, the current is 100 / 50, or 2 amps. Calculate the resistance, in Ohms, by dividing the voltage by the current. Ohms law states that voltage = current x resistance, so by rearranging the formula resistance = voltage / current.
What resistor do I need to drop 12V to 6v?
It’s possible to step 12 volts down to 6 volts by incorporating a pair of 10,000-ohm resistors into the circuit.
Do 12V LEDS need resistors?
Yes. There really is no stand alone 12V LED. They all need ballast resistors for different voltage levels.
What is the color code for a 68 ohm resistor?
68 Ohm Resistor Color Code: Blue, Gray, Black, Golden.
How do you calculate the resistance of a 12 volt resistor?
Resistor = (Battery Voltage – LED voltage) / desired LED current. So assuming a 12 volt power source and a white LED with a desired current of 10 mA; The formula becomes Resistor = (12-3.4)/.010 which is 860 ohms. Since this is not a standard value I would use an 820 ohm resistor.
How do you calculate the resistor value for LED lights?
How to Calculate Resistor Value for LED Lighting. We’ll use the following formula to determine the resistor value: Resistor = (Battery Voltage – LED voltage) / desired LED current. For a typical white LED that requires 10mA, powered by 12V the values are: (12-3.4)/.010=860 ohms.
How many resistors do I need to power a 5V led?
However, if you are using a 5 V supply voltage, then a 90 Ω resistor is needed. As you can see, the resistor value increases as the supply voltage increases. Example 2: If you are using a yellow LED, then it has a typical forward voltage of 1.8 V.
How do you find the value of a resistor in parallel?
Resistor Value (LED’s in parallel with separate Resistor) = (Vsupply – VF)/ IFHere, Total forward voltage (VF) of LED’s = 2 and forward Current (IF) 20mA (i.e. 20mA) (Note: this is a parallel circuit, but we are finding the value of resistor for each section, not for whole circuit.