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Engineer an LED Night-Light

Summary

Areas of Science
Difficulty
 
Time Required
Short (2-5 days)
Credits
Ben Finio, PhD, Science Buddies
Two photos of an assembled night light with it off on the left and lit on the right
*Note: For this science project you will need to develop your own experimental procedure. Use the information in the summary tab as a starting place. If you would like to discuss your ideas or need help troubleshooting, use the Ask An Expert forum. Our Experts won't do the work for you, but they will make suggestions and offer guidance if you come to them with specific questions.

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Abstract

Night-lights can be found in many homes; you might even have one in your bedroom! Using a night-light is a great way to avoid stubbing your toe on furniture during a midnight trip to the bathroom. In this fun engineering project, you will design and build your own night-light. You will need to build the circuit, but you will also need to think about the physical design of the product. Most people probably do not want an ugly, bare circuit board sitting around their house. Can you make a functional, aesthetically pleasing case or enclosure for your circuit? You could make a case using craft materials, wood, or even a 3D printer if you have access to one.

If you need some help getting started and learning how to build an LED night-light circuit, first watch this video for an overview and explanation of how the circuit works:

Make an LED Night-Light

The parts to build the circuit are available in the DIY Night-Light Kit. The kit includes:

To wire the circuit, see the diagrams in Figures 1 and 2. Figure 1 shows the connections directly between the leads of the different circuit components. You can use this diagram if you plan to solder the circuit yourself on a protoboard (you will need to decide how to arrange the components). Figure 2 shows the circuit on a breadboard. You can follow this diagram exactly. If you do not know how to use a breadboard, see the breadboard tutorial in the Bibliography.

Breadboard diagram for the connections of an LED night light circuit
Figure 1. Wiring diagram for the LED night-light circuit. Image made with Fritzing.

Breadboard diagram for an LED night light circuit
Figure 2. Breadboard diagram for LED night-light circuit. Image made with Fritzing.

How does the circuit work? Remember to watch the video (starting at about 3:25) for an explanation. Figure 3 shows a copy of the schematic. See the Bibliography if you do not know how to read a circuit schematic. The potentiometer and photoresistor are combined to form a voltage divider. The output of the voltage divider turns the MOSFET on and off (therefore turning the LED on and off) depending on the amount of light hitting the photoresistor. The potentiometer allows you to adjust the threshold at which the LED will turn on.

Circuit diagram for an LED night light
Figure 3. Circuit schematic for the LED night-light.

Bibliography

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Ask an Expert

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Careers

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Have you always loved art? Do you have a good eye for beauty, balance, and form? How would you like to see your designs show up in toy stores? Or in a sporting goods store? Or at a car dealer? Commercial and industrial designers create the shape and form of every type of manufactured good that you can think of—from toys, sporting goods, and medical equipment to high technology products, furniture, toothbrushes, and toasters. They design the form of new products that are as beautiful and… Read more

Contact Us

If you have purchased a kit for this project from Science Buddies, we are pleased to answer your questions.

In your email, please follow these instructions:
  1. What is your Science Buddies kit order number?
  2. Please describe how you need help as thoroughly as possible:

    Examples

    Good Question I'm trying to do Experimental Procedure step #5, "Scrape the insulation from the wire. . ." How do I know when I've scraped enough?
    Good Question I'm at Experimental Procedure step #7, "Move the magnet back and forth . . ." and the LED is not lighting up.
    Bad Question I don't understand the instructions. Help!
    Good Question I am purchasing my materials. Can I substitute a 1N34 diode for the 1N25 diode called for in the material list?
    Bad Question Can I use a different part?

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General citation information is provided here. Be sure to check the formatting, including capitalization, for the method you are using and update your citation, as needed.

MLA Style

Finio, Ben. "Engineer an LED Night-Light." Science Buddies, 28 Dec. 2021, https://www.sciencebuddies.org/science-fair-projects/project-ideas/Elec_p090/electricity-electronics/led-night-light?from=Blog. Accessed 26 June 2022.

APA Style

Finio, B. (2021, December 28). Engineer an LED Night-Light. Retrieved from https://www.sciencebuddies.org/science-fair-projects/project-ideas/Elec_p090/electricity-electronics/led-night-light?from=Blog


Last edit date: 2021-12-28
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