- Physics
- Class 1 to 9
- Printed report included
ONTEX ELECTRONICS NOT GATE (Logic Gate) Educational Circuit Board with Justified Truth Table and Printed Report for Kids
Code B07LDCCWTW
- Paid for and delivered by Amazon. The current price and the delivery date for your PIN code are shown there.
- Sold by Gurukul Technicals Institute, Delhi.
- Need a different topic, a custom version or a school order? Ask on WhatsApp.
In this project guide
Physics
About this model
This NOT gate educational circuit board demonstrates the simplest logic gate, the inverter, whose output is always the opposite of its input. The listing says it comes with a justified truth table and a printed report, which helps a student explain the result in an exhibition or a practical file.
How it works
The science behind it
The idea the model demonstrates, in words you can use in your report and when you explain it.
A logic gate is a circuit that works with only two states: 1 (HIGH, a voltage present) and 0 (LOW, almost no voltage). The NOT gate has a single input A and a single output Y, and its Boolean expression is Y = Ā, read as 'NOT A' or 'A bar'. Its truth table has just two rows: when A = 0, Y = 1, and when A = 1, Y = 0. A NOT gate is often built from one transistor used as a switch. When the input is LOW, the transistor is off and a resistor pulls the output up to HIGH. When the input is HIGH, the transistor turns on and pulls the output down to LOW. Inverters like this are among the most common building blocks inside the processor of every computer and mobile phone, where they work alongside AND and OR gates to carry out calculations.
Make it yourself
Make a NOT gate circuit board yourself
Build your own version from scratch, or use the steps to understand how the ready-made model is put together before you present it.
What you need 8
Step by step 8 steps
Wire the input switch so ON connects the input line to the positive rail, and fit the 10 kΩ pull-down from the input line to negative so OFF is a clear 0.
Connect the input line through the 10 kΩ resistor to the transistor's base, and the emitter to the negative rail.
Connect the collector to the positive rail through the 1 kΩ pull-up resistor; the collector is the output Y.
Connect the output LED from Y to negative (longer leg towards Y), and the input LED with its 1 kΩ resistor from the input line to negative.
Switch on with the input at 0: the transistor is off, the pull-up holds Y HIGH and the output LED lights.
- Switch the input to 1
The transistor turns on and pulls Y down to nearly 0 V, so the output LED goes out.
Measure the input voltage, the base-emitter voltage and the output voltage in both states, and write them in the truth table to justify each 0 and 1.
Build a second identical stage, or use one gate of the CD4069, after the first and show that two NOT gates in a row give back the original input.
Read this first
Safety first
Go through these points before you build or switch anything on. Younger students should do this with an adult.
- Use only the 9 V battery; logic boards never need mains power.
- Keep the 10 kΩ base resistor in place, as a base wired straight to the supply can destroy the transistor.
- Touch a grounded metal object before handling the CD4069, and tie its unused inputs to a rail.
- Solder only with an adult.
Troubleshooting
If something does not work
The usual problems with this model and how to fix them. Open a problem to see the fix.
The output LED stays on when the input is 1
The transistor is not switching on. Check its pin order and the base resistor, and that the switch really connects the input to positive.
The output LED never lights
Check the LED's direction and the 1 kΩ pull-up; without it the output cannot go HIGH.
The output LED glows dimly when the input is 1
Measure the collector voltage; it should be only a few tenths of a volt. If it is higher, the transistor is not fully on, so check the base resistor's value and the battery.
The input LED glows with the switch off
The pull-down resistor is missing, so the input is floating. Fit the 10 kΩ resistor from the input line to negative.
Exhibition day
How to present it
A running order for the exhibition table or the practical, step by step.
Write the two-row truth table on a chart beside the board and tick each row as you demonstrate it.
Show input 0 first, then input 1, and say aloud what the output does each time.
Point out that a NOT gate has only one input, unlike AND, OR and NAND gates.
End by naming where inverters are used, such as inside computer processors.
Practice
Viva questions
Practice questions on this model, with short answers. Try each one aloud before you open the answer.
What is the Boolean expression of a NOT gate?
Y = Ā, which means the output is the complement of the input.
Why is a NOT gate also called an inverter?
Because it inverts its input: a 1 becomes 0 and a 0 becomes 1.
How many inputs does a NOT gate have?
Only one. The other basic gates, such as AND and OR, can have two or more inputs.
What is the symbol of a NOT gate?
A triangle with a small circle, called a bubble, at its output. The bubble stands for inversion.
Project file
Project file outline
The headings of the project file, in order. Give each heading its own section and write it in your own words.
The listing includes a printed project report: use this outline to check that your own file covers every part.
Free ebook: Writing a Science Project FileContents
- Aim: to verify the truth table of a NOT gate (inverter)
- Logic levels 0 and 1, and what they mean as voltages
- Symbol, Boolean expression and truth table of the NOT gate
- How one transistor works as an inverter, with the circuit diagram
- Justified truth table: measured input, base and output voltages in each state
- Two inverters in a row, and where NOT gates are used
- Precautions and sources of error
- Conclusion
Buying checklist
Before you buy
What to check before you order the model, and what to do when it arrives.
1Before you order
- Check that a NOT gate project suits your class and the chapter on logic gates.
- The listing says a justified truth table and a printed report come with it; compare them with your textbook and add your own measured voltages.
- Read the listing for the supply needed; do not assume a battery is included.
- Keep the box so the switch and LEDs are not damaged in transport.
- Check the delivery date for your PIN code on the marketplace, and order well before the exhibition or practical.
- Practise explaining it. Judges ask what the model shows and why; knowing the science matters as much as the model. The viva questions above are a good place to start.
2When it arrives
- When it arrives, test both input states and measure the output voltage in each.
Next steps
Take it further
Ways to turn this model into a bigger investigation or a stronger exhibition entry.
Use two gates of a CD4069 with the 470 kΩ resistor and the 1 µF capacitor to build a blinking astable circuit, and explain why inverters can oscillate.
Combine your NOT gate with a NOR or NAND gate to show how inverters help build the other gates.
Vary the input slowly with a potentiometer and plot the output voltage against it, to see the narrow range where the inverter switches.
Audience
Who it suits
Class 9 to 12 students preparing a logic gates project or practical, and computer science students who are learning Boolean logic.
- ClassClass 1 to 9
- SubjectPhysics
- Project reportPrinted report included
Free to read
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