LED Circuit Battery Level IndicatorBy Rohit Choudhary
This instruction guide will take you through the steps of creating your own battery level indicator. The design utilizes a simple resistor-LED circuit in which LEDs will turn on depending on the voltage of the battery that is used to complete the circuit. To begin it is important to know the basics of how a breadboard is structured. Consider the diagram below. Keep this in mind when creating your breadboard project.
- 1x Breadboard
- 5x 1k Ohm Resistors
- 5x Colored LEDs: White, Red, Orange, Yellow and Green
- 1x 9V Energizer Alkaline Battery
- 1x Battery Clip
Battery Indicator STEP 1Orient the breadboard so that Row J is closest to you and Row A is farthest from you. When using LEDs, keep in mind that the longer wire of the LED is the positive end, the anode, and the shorter wire is the negative end, the cathode.
With this in mind, begin by plugging in the negative end of the LED on column 5, row A and the positive end having a 1 pin gap in row A.Continue by attaching the rest of the LEDs in a diagonal pattern with the negative end being 1 pin in front of the previous LEDs positive end and the positive end being on row A.
For example, the red LEDs negative end is in row B column 7 and the positive end is in row A column 9. The order of the colors does not affect the build but keep in mind the rightmost LED will be the lowest level and the leftmost LED will be the highest level.
Battery Indicator STEP 2Use 5 1k ohm resistors to connect the bottom rails positive row (labeled with a (+) sign and colored red on each rail) to the column containing the positive end of each LED (e.g. the first resistor would have one end in the positive rail and the other end in column 7, the column where the white LEDs positive end is placed).
Battery Indicator STEP 3Attach the 9V battery to the battery clip. When placing the two wires, be very careful to attach the correct ends to the correct positions. The red wire on the battery clip is the positive end and the black wire is the negative. Attach the positive wire (red) to the positive rail in line with your resistors. Attach the negative wire in the same column as your rightmost LEDs negative wire (in the image below that is column 5). Once the negative wire is placed into the pin, the LEDs will light up immediately! Below are examples of two different 9V batteries being tested in which you can see the variation in battery levels.
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