Night Light Electronics Workshop

Workshop to learn basic electronics and build a nightlight

The Starlight Nightlight workshop will build and take home an automatic night light using a LED (light-emitting diode) and a few basic electronic components. The project aims to teach students about basic circuitry and electronics while creating a functional and practical device. The project involves constructing a simple circuit that connects the LED to a battery through a transistor and a light sensor. The Starlight Nightlight workshop is a great introduction to electronics and a fun way to create a useful device.

Time: I’m thinking 1.5 hours Date: 21st April 10:30. Students: 10 to 12 (happy for parents to stay, help and join in the fun)

Example completed unit:

Participants will learn:

  • How a LED Works and different types of LEDs
  • What do a Resistor, Transistor, and Light-dependent resistor do in a circuit.
  • What are Ohms Law and Kirchhoff’s Voltage Law
  • Series and Parallel circuits
  • How to connect a LED to a battery correctly and safely
  • Why transistors changed the world and how we use them
  • How to build a circuit to monitor light levels and activate a Night Light

Demo Circuit:

Step 1

Make a LED Light using the battery. Parts:


  • Connect Battery, LED and 100 Ohm resistor in series.
  • Measure Voltage at Battery
  • Talk about Kirchhoff’s Voltage Law = KVL
  • Let’s find the voltage over the resistor by measuring the LED
  • Measure Voltage at LED
  • Use the above to work out what the resistor voltage drop is.
  • Measure to confirm.
  • Now we have the Voltage and the Ohms, let’s discover the mA using Ohms Law
  • What is mcd? Lets try different types of LEDs and see the brightness difference

Step 2

Make a voltage divider (Just like the loop KVL), only this time using the Light Dependent Resistor Parts:

  • 3V/2.4V Battery Pack
  • LED
  • TRIMPOT 103 10K Potentiometers
  • LDR CE09439 Light-dependent resistor


  • Connect Trimpot and LDR in series to the battery
  • Connect LED between Trimpot and LDR then to Battery
  • Does the LED light?
  • What if the LDR is covered?
  • What if the TRIMPOT is adjusted?
  • What are we doing?
  • We are making a Voltage Divider.
  • Why does the LED go out when the LDR sees the light?
  • Can we measure the voltage across the LED? it’s small.
  • How can we make the LED bright again?

Step 3

Amplify the voltage/current to full levels needed by the LED Parts:

  • 3V/2.4V Battery Pack
  • LED
  • TRIMPOT 103 10K Potentiometers
  • LDR CE09439 Light-dependent resistor
  • Transistor PNP
  • 100 Ohm Resister


  • Lets remove the LED from the voltage divider
  • Insert the transistor
  • Insert the Resistor to limit the current as in Task 1
  • Insert the LED.
  • Lets adjust the voltage divider (if needed)
  • Now we can set the light level.
  • We have an Automatic Night Light.

Step 4

Finish it up for use Tasks:

  • Unstick the backing
  • Place on the battery pack
  • Put a cover over it?

Ohms Law: At 2.4V, what will be the mA using 47 Ohms:

First Project cost: $64.70 Multimeters x 6 Purchase of many parts for learning that didn’t end up going in this kit.

Take-home kit: $1.70 3V Battery case $0.28 LDR $0.40 Yellow Bright LED $0.15 Potentiometer (102 or 103. 203 is too high) $0.57 PNP Transistor (Cheaper at core-electronics doh!) $1.20 Breadboard Total $4.30 per person


The small components can go into the battery compartment. Then print with light cardboard and fold in half over it to make a printed pouch.

From Website:

Purchasing test parts from local Jaycar store. Cost = ?

If purchased from Jaycar in Tasmania, what would be the cost?

Purchasing parts from digi-key wholesale

Cost options for bulk

Needed per person: $7 per person?


First version: LED - Long lead is positive.

LED Tests: Super bright Yellow on 3V AA batteries. 47 Ohms - still very bright. Enough to leave spots on eyes.

TRIMPOT: miniature “Trimpots” have codes to represent their value. For example, 101 (100 Ohm), 102 (1K), 103 (10K), 104 (100K), 105 (1M)

  • 103 should be a match for the LDR at 10-20K

LDR CE09439 Light dependent resistor

  • Resistance @ 10 Lux = 10-20k ohms


Learning Program: Use the LED (with 47 Ohm resister) as the indicator to demo voltage divider.

Last steps: Slides

Time Spent:

  • 2023-04-15 4h Slides and learning electronics.
  • 2023-04-03 2h Developing training material
  • 2023-03-24 1h Building first kid
  • 2023-02-10 2h Initial research and product investigation.
  • 2023-02-10 1h research cost to buy from Leading Edge - Jaycar reseller for a first test run.