Coderdojo Athlone

LED and resistors

Objectives

• Take a series of Tinkercad online tutorials to get started
• Understand how to read a basic circuit diagram
• Build a LED (Light Emitting Diode) and Resistor Circuit
• Conduct a series of experiments to understand some basics principles about electronics

Prerequisites

• It is you are already familiar with some of basic electronic components
• For a recap on components see Basic Electronic components, how and why to use
• Recap on Resistors and what they do

Online tutorials

• Follow the Tinkercad Starter Tutorials Online Series to get started. This tutorial series will assist you and help you to understand the following:
  • How to use Tinkercad to start simulate circuits
  • How to edit, wire and add components to circuits
• Follow the Tinkercad Further Lessons Online Tutorial Series to learn:
  • How to use breadboards
  • Ohm’s law
  • The difference between series and parallel circuits

Reading basic circuit diagrams / schematics

• Follow the How to Read a Schematic for a good overview about how to read basic electronic circuits
• Read Sparkfun - How to Read a Schematic and keep it handy as a reference.

Build your first circuit in Tinkercad

Build a simple LED resistor circuit diagram in Tinkercad.

Simple LED resistor circuit diagram

Components

• 9V battery
• Jumper wires
• LED (any colour you prefer!) (x1)
• Diode
• Switch
• Resistor (220 Ω)
• Potentiometer (1kΩ )

Breadboard layout

The following shows a basic LED resistor circuit (without the switch, diode or potentiometer - you can add these yourself as an experiment!)

Experiments

The following experiments will help understand the basics ideas:

1. Build the Battery LED circuit shown above. However, use a 9V DC supply rather than 3V.
2. Measure the voltage across the LED when the LED is turned on. Measure the voltage across the resistor. What is the sum of the voltage ?
3. Reverse LED pins around. What happens ?
4. Take out the resistor and put 9V across the LED ? What happens ? Why ?
5. Choose different colour for LED
6. Switch LED and resistor around. What happens ? Why ? Are the resistor and LED in series or parallel ?
7. Add a diode in series to LED1
8. Reduce voltage from 9V to 3V. What effect does this have to the circuit ?
9. Revert to back use 9V battery again
10. Add a potentiometer to the circuit in replacement of the resistor. Vary the resistance of the potentiometer when the circuit is active and note how this effects the LED.
11. Measure resistance across the potentiometer as you vary the resistance.
12. Add a switch to the circuit (single pole single throw SPST)
13. Measure current through circuit. In addition use Ohm’s law to calculate the current, when a 9V battery is used and a 270 Ohm resistor is used.
14. Add more LEDS in parallel to existing circuit (different colours)
15. Learn more about resistors and resistor colour codes
16. Use mnemonics to remember the resistor colour codes “Bad Booze Rots Our Young Guts But Vodka Goes Well” is my favorite mnemonic to remember the resistor colour code list!
17. Reverse the direction of the diode

Quiz

• Describe to a friend how you use breadboard to prototype a circuit and how the pins of the breadboard are interconnected.
• Some components have a _____ - a positive and a negative end.

• What is the symbol for the following component

  

• Name some components with a positive / negative terminal.
• Battery has a voltage measured in __ ?
• Current flows through a electronic circuit. Current in measured in ___ ?
• Resistors have a ___ code which tell you ____ ?
• If too much current flows through an LED what happens ?
• If a resistor has colour codes Red Black Orange Gold. What is its resistance ?

• Use Ohm’s law to calculate resistance. Imagine we want 20 mA of current flowing through the LED in the following circuit. What resistance value do we need for the resistor ?

  

Report

• Write about what you learned, you can also write about your own experiments you conducted and what you discovered.
• A mentor can help publish your experiments to the Coder Dojo Athlone Projects website!