Engineered Wood AND OR NOT Logic Gates Educational Circuit Board
Code B07LDC38L1
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- Sold by Gurukul Technicals Institute, Delhi.
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In this project guide
Physics
About this model
An educational circuit board for the three basic logic gates, AND, OR and NOT, from which every other gate can be built. It is a good starting point for learning truth tables step by step before moving on to universal gates and combinational circuits.
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.
Gates commonly use positive logic, where a high voltage stands for 1 and a low voltage for 0. Teaching boards often build basic gates from simple parts. An AND gate can be made from two diodes and a resistor: if either input is at 0, its diode conducts and pulls the output low, so the output is high only when both inputs are high, giving Y = A·B. An OR gate uses two diodes facing the other way, so a high on any input passes to the output, giving Y = A + B. A NOT gate uses a transistor as a switch: a high input turns the transistor on and pulls the output low, while a low input turns it off and the output goes high, giving Y = A'. Combining these three gives NAND, NOR and every other gate. A house doorbell that rings from either the front or the back door button is a simple OR circuit.
Make it yourself
Make an AND, OR and NOT gate 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 9
Step by step 8 steps
Divide the base into three sections and label them AND (Y = A·B), OR (Y = A + B) and NOT (Y = A').
Wire each input switch so its middle pin is the input line, one outer pin goes to positive (1) and the other to negative (0). Add a red LED with a 470 Ω resistor from each input line to negative to show when it is 1.
- AND gate
Connect two diodes with their banded ends towards the two input switches and their other ends joined at the output. Add 470 Ω from the output to positive, and a green LED with a 220 Ω resistor from the output to negative.
- OR gate
Connect two diodes with their plain ends to the input switches and their banded ends joined at the output. Add a green LED with a 470 Ω resistor from the output to negative.
- NOT gate
Connect the input switch through 10 kΩ to the transistor's base, the emitter to negative, and 470 Ω from the collector to positive. Add a green LED with a 220 Ω resistor from the collector to negative.
Mark the 0 and 1 positions beside every switch.
Switch on and try every input combination on each gate, noting whether the green LED is on (1) or off (0).
Fill in the truth tables and check them against the expected results.
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 AA cells; this board never needs anything more than a few volts.
- Solder only with an adult present, in a room with fresh air, and keep the iron in its stand.
- Trim the leftover component legs after soldering, pointing them down into a bin so they do not fly towards your eyes.
- Switch off when not demonstrating so the cells do not run down.
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 AND output LED stays on whatever the inputs
The diodes are probably reversed or not soldered, so they cannot pull the output down. Check that both bands face the input switches.
The OR output works for one input but not the other
One diode is reversed or has a broken joint. Check its direction and resolder it.
The NOT output does not change
The transistor's legs may be in the wrong order, the base resistor may be missing, or the LED may be in the collector line instead of from the collector to negative.
An input LED does not show 1
The LED may be reversed or the switch's outer pins may be swapped. Check with a multimeter that the input line reads about 4.5 V in the 1 position.
Exhibition day
How to present it
A running order for the exhibition table or the practical, step by step.
Test each gate with every input combination and tick off its truth table on a chart as you go.
Explain positive logic first: a high voltage means 1 and a low voltage means 0.
If the board lets you connect gates together, join an AND to a NOT to show how a NAND is made.
Give a daily-life example for each gate, such as a fridge light for NOT: it glows when the door is not closed.
Practice
Viva questions
Practice questions on this model, with short answers. Try each one aloud before you open the answer.
What is positive logic?
In positive logic, the higher voltage level represents 1 and the lower voltage level represents 0.
What is the output of an AND gate when one input is 0 and the other is 1?
The output is 0, because an AND gate gives 1 only when all its inputs are 1.
How does a transistor work as a NOT gate?
A high input switches the transistor on and pulls the output low, while a low input switches it off so the output goes high.
Which gates are combined to make a NOR gate?
An OR gate followed by a NOT gate makes a NOR gate.
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.
Free ebook: Writing a Science Project FileContents
- Aim: to verify the truth tables of the AND, OR and NOT gates
- Introduction: digital signals, binary 0 and 1, and positive logic
- AND gate using diodes: circuit, Boolean expression Y = A·B and truth table
- OR gate using diodes: circuit, Y = A + B and truth table
- NOT gate using a transistor as a switch: circuit, Y = A' and truth table
- Observations: the output for every input combination
- Limitations of diode logic and why gates are made as integrated circuits
- Uses of logic gates in calculators, computers and alarms
- Conclusion and bibliography
Buying checklist
Before you buy
What to check before you order the model, and what to do when it arrives.
1Before you order
- Logic gates appear in physics and computer science syllabuses at different levels; check which gates and what kind of project your teacher expects.
- Read the listing to see how the board is powered and whether batteries are mentioned.
- Keep spare cells and the box for the exhibition day.
- 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, go through every input combination and write the truth table yourself to check that each gate works.
Next steps
Take it further
Ways to turn this model into a bigger investigation or a stronger exhibition entry.
Join the AND and NOT sections to make a NAND gate, and explain why NAND is called a universal gate.
Use the gates for a real job, such as a seat-belt reminder that sounds when the ignition is on AND the belt is NOT fastened (Y = A·B').
Measure the actual output voltages for 0 and 1 with a multimeter and discuss how far they are from the ideal values.
Audience
Who it suits
Suits Class 11 and 12 physics investigatory projects and computer science students starting digital logic.
- SubjectPhysics
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