The calculation of the resistor for LED
calculated resistor for LED light - a very important point before turning on the LED to the power source. Since it affects the way the LED will work .
if rezister will have a very tiny resistance , the LED may be damaged ( burn out , because by him will go very high current) , and if the resistance becomes very large, then the LED will emit the light is very weak . Resistance for LEDs is calculated using the following formula : R = (VS - VL) / I VS - the power supply voltage ( V) . VL - LED power supply (usually 3.5 volts ) . I - LED current (eg 20 mA = 0.02 A or 30 mA = 0.03 A)
Make sure that your chosen current is less than the maximum current available on this LED. Move the value from milliamps to amps . Thus the result of calculation will be the size of the resistor in ohms ( ohms).
if the calculated value of the resistor does not coincide with the nominal value of an ordinary resistor , you need to select the resistor larger neighbor . You can select more than one first impedance in order to save more power. However, the LED radiation in this case would be less bright . For example : If the power supply voltage = 9 volts and you have a reddish LED (VL = 2V), the current is I = 20mA = 0.02A, R = (9V - 2V) / 0.02A = 350 ohms. You need to select 390 ohm resistor ( near the highest value ) . Series connection of the LEDs The systematic connection of LEDs "title =" Series connection of the LEDs "/> Series connection of the LEDs is possible and can even be beneficial if you need to connect directly a number of LEDs. For example, if you try to make Christmas Christmas garland . Use is that all the LEDs will be fed by the same current as a single LED and a power supply would spend the same power as a single LED. All LEDs combined successively fed by the same current and therefore better that they were of the same type. The power supply must provide at least by 2 volts per LED ( 4 volts on a blue or pure white ) , plus at least another 2 volts to the resistor . To calculate the resistor need to add up all the voltage for the LED and use this value as the VL. Example calculation of resistance for LED: Red, yellow and green LEDs are connected in series and have a need for a voltage of 3 × 2V + 2V = 8V. Ideally use the power supply at 9 volts. VL = 2V + 2V + 2V = 6V ( total load of 3 series-connected LEDs ) . If the power supply VS = 9V and the required current I = 15mA = 0.015A , resistor R = (VS - VL) / I = ( 9 - 6) / 3 = 0.015 / 0.015 = 200 ohms. The next higher standard value settings The base of synonyms - To use the base «Big one» - To use the base «Small one» - To use the base «Small two» The main - Do not substitute synonyms - Substitute the first synonyms - Occasional substitute synonyms additionally - Highlight the background with synonyms
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