How to connect 5mm led lights to 9 volt battery. Should I use a Resistor? If yes, which resistor should I use?
Answers
Explanation:
You can use light emitting diodes (LED) in many applications to provide status lights and illumination. LEDs are true diodes, meaning that they will only conduct electricity in one direction. LEDs emit light at a single frequency (color), which you cannot modify. The brightness of an LED is directly proportional to the amount of current flowing through it, and LEDs turn on and off much more quickly than an incandescent bulb. To limit current, connect a resistor in series with an LED. Follow a few simple steps to power an LED with a 9-volt battery.
Examine the data sheet for the LED you wish to use. Identify the specifications for maximum current (Imax) and typical forward voltage (Vf typ).
Example: 9-volt battery LED Imax = 20milliamps (mA) Vf typ=2 Volts (V)
Determine the voltage drop across the resistor (Vr). This voltage will equal the battery voltage (Vbatt) minus the Vftyp for the LED.
Example: Vr=Vbatt-Vftyp Vr=9 volts - 2 volts = 7 volts
Calculate a working current (Iwork) for the LED—typically about 75 percent of the maximum current.
Example: Iwork= Imax x 0.75 Iwork=20mA x 0.75 = 15mA
Choose a resistor value to allow 15mA of current to flow across.
Example: I=V/R ( Ohm's Law: Current = Voltage/Resistance) 15mA = Vr/R 15mA = 7 volts/R R=466 ohms
Select a 466-ohm resistor, or the next highest value of standard resistor.
Connect one end of the resistor to the positive terminal of the battery.
Connect the other end of the resistor to the positive (anode) terminal of the LED.
Connect the cathode of the LED to the negative terminal of the battery. The LED should illuminate.
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ABOUT THE AUTHOR
How to Stop LED Lights From Blinking Too Fast
Resistors and capacitors stop LED lights from blinking too fast.
Updated April 24, 2017
By Mark Stansberry
If you find LEDs that blink to fast to suit your taste, you can slow them down with some simple circuit modifications. The actual procedure you will need to follow depends on the circuit design that controls the blink rate of your LEDs. Most circuits use resistors to control LED blink rate. Once you find where the resistors that control the blink rate are located, you can adjust the resistors' value for a slower blink rate.
Obtain the schematic of the LED flasher circuit you want to stop the LEDs from blinking too fast. Locate the resistors on the circuit schematic. Look for any notes on the schematic that may give you a clue as to what resistors control the blinking rate. Write down the values of the resistors that are on the schematic.
Open up the LED flasher circuit so that you can see the components that are in the flasher. Locate the resistors on the printed circuit board. Read the values written on the resistors and match them to the resistors on the schematic.
Attach a variable resistor to the right and left leads of one of the resistors on the circuit board. Turn on the flasher. Adjust the value of the variable resistor with a small screwdriver and observe whether or not the LED blinking rate slows down with the change in resistance. Remove the variable resistor and attach it to the left and right leads of another resistor. Continue in this fashion until you locate the resistor that controls the LED blinking rate.
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