LED Current Limiting
Find the series resistor for one LED or a string: exact ohms from supply and forward voltage, the next E12 value, real current and resistor wattage.
Circuits and Components
5 tools
Which Circuits and Components tool do you need?
| Tool | What it answers |
|---|---|
| Band Pass Filter Calculator | A passive RC band-pass filter has two corners, each at f = 1/(2πRC). |
| LC Filter Calculator | An LC filter's cutoff frequency is fc = 1 ÷ (2π√(LC)). |
| LED Array Calculator | An LED array calculator splits your LEDs into series strings that fit under the supply voltage, then sizes one current-limiting resistor per string. |
| LED Current Limiting | An LED current limiting resistor is sized as R = (supply voltage − LED forward voltage × number of LEDs) ÷ current. |
| Low Pass Filter Calculator | A first-order RC low-pass filter has a cutoff frequency fc = 1 ÷ (2πRC); an RL version uses fc = R ÷ (2πL). |
All tools
LC Filter Calculator
Find the cutoff frequency of a second-order LC low-pass or high-pass filter from L and C, plus the characteristic impedance √(L/C) it should drive.
Band Pass Filter Calculator
Find the lower and upper cutoff, centre frequency, bandwidth and Q of a passive RC band-pass filter from R1, C1, R2 and C2, with each step of the working shown.
LED Array Calculator
Plan an LED array: how many LEDs fit in series per string, how many parallel strings you need, the resistor value and its wattage for each string.
Low Pass Filter Calculator
Find the −3 dB cutoff frequency of a first-order RC or RL low-pass filter, plus the time constant and the gain and phase at any signal frequency.