How to Dim LED Light Bulbs

Written by mark stansberry
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How to Dim LED Light Bulbs
You'll need resistors to dim LED light bulbs (pendelleuchte image by kernel from

Dimming LED lights is one way to help save on electricity costs and it is another way to add dimension and creative flair to electronic design projects.

The brightness of an LED is dependent on the amount of electric current that flows through it. However, small changes in electric current may change the brightness levels considerably. This means that you must be careful to select a resistor that will adequately, but not excessively, dim your lights.

Skill level:

Things you need

  • Resistors
  • LED flashlight
  • Flashlight batteries

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  1. 1

    Open the LED flashlight to access the LED. Find the wire or metal connection that connects the LED to the battery. Disconnect this connection.

  2. 2

    Connect a 1000-ohm resistor between the open wire (open connection) and the LED terminal. Turn on the flashlight and note the brightness level.

  3. 3

    Turn off the flashlight. Replace the 1,000-ohm resistor with a 5,000-ohm resistor. Turn on the flashlight again and note the level of brightness.

  4. 4

    Replace the 5,000-ohm resistor with an even higher value, like 20,000 ohms, if the brightness levels in the 5,000-ohm circuit is not noticeably less than the brightness level obtained with the 1,000-ohm circuit.

  5. 5

    Continue increasing the value of resistor to reduce the brightness level. Decrease the resistor value to increase the brightness level.

Tips and warnings

  • Obtain the current vs. brightness specification chart for the LED you are using if you want to design circuits at specific brightness levels.
  • Determine the levels of brightness and the corresponding currents needed to obtain those levels from the brightness/current charts. Calculate the resistance value needed to obtain the current for the specific brightness level.
  • You should be trained in electronic safety before you work on electronic circuits. Otherwise work under the supervision of a trained engineer or electronic technician.

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