Chapter 2 · Book pp. 25–40

Basic Electronic Components

แนะนำอุปกรณ์อิเล็กทรอนิกส์พื้นฐานในโปรแกรม Tinkercad

Before building bigger circuits you need to know the basic parts in Tinkercad: what each one does, how it is drawn, and how to wire it the right way round. This chapter tours them one by one, with tips for using each in the simulator.

⚠️ Simulation is not the real world

A simulator does its best, but it is never perfect. When you build a circuit for real, some results may differ from Tinkercad — always think about this before you take a design off the screen.

2.1 Resistor ตัวต้านทาน

A resistor limits the current flowing in a circuit.
Its unit is the ohm (Ω). 1 Ω is the resistance that lets 1 A flow when there is 1 V across it.
The usual resistor is a small cylinder with colour bands: a carbon or metal film on a ceramic core, with a leg at each end. Tiny boards use surface-mount resistors that have no legs.
In Tinkercad you can set any value, from picohms (pΩ) up to gigaohms (GΩ).

**Fig 2-1**The resistor in Tinkercad. It limits current according to Ohm’s law and has no polarity, so either leg can go either way. Choose the unit from the drop-down list

2.2 Variable resistor ตัวต้านทานปรับค่าได้

A variable resistor has a knob to turn or a slider to move. The usual name is a potentiometer (“pot”).
Uses: volume controls, adjusting a voltage, the brightness or contrast of a display.
There are single-turn and multi-turn types. Both have 3 legs; the middle leg (the wiper) is the one whose resistance changes.

**Fig 2-2**The potentiometer in Tinkercad: a real part, its symbol and its 3 legs. You can only turn it while the simulation is running. Wired to the middle leg, the resistance changes as you turn it; wired across the two outer legs, it does not

2.3 Light-emitting diode (LED) ไดโอดเปล่งแสง

An LED is a semiconductor that gives out light when a DC voltage is applied the right way round. The colour depends on the semiconductor material.
Round LEDs come in many sizes, up to about 12 mm across, in clear or coloured plastic. Put several LEDs together in a pattern and you can show numbers: a seven-segment display.
Tinkercad has 6 colours: red, yellow, orange, blue, green and white. The rotate button turns a part 30° per click.

**Fig 2-3**The LED in Tinkercad: click a part (blue frame) to change its properties, such as the colour. The anode (+) and cathode (−) legs, the six colours when off, and rotating 30° per click

2.4 Non-polarized capacitor ตัวเก็บประจุแบบไม่มีขั้ว

A capacitor (or condenser) stores electric charge.
Inside are two metal plates separated by an insulator called the dielectric. The type of capacitor is named after the dielectric: ceramic, mylar, polyester, polystyrene and so on.
In Tinkercad the capacitance goes from picofarads (pF) to gigafarads (GF), but real non-polarized capacitors only reach a few microfarads (about 1–6.8 µF). If you plan to build the circuit for real, keep to pF, nF and µF.

**Fig 2-4**A non-polarized capacitor: (a) its structure — two plates, the dielectric and the legs; (b) its circuit symbol

**Fig 2-5**The non-polarized capacitor in Tinkercad. Choose the unit of capacitance; it has no polarity, so it can be connected either way round

2.5 Light-dependent resistor (LDR) ตัวต้านทานแปรค่าตามแสง

An LDR changes its resistance with the amount of light falling on it. Most are made of cadmium sulfide (CdS) or cadmium selenide (CdSe) on a ceramic base.
In the dark it is about 2 MΩ. In light the resistance drops, but not below about 100 Ω.
It responds best to light of about 600 nm, inside the range our eyes see (400–700 nm). So it reacts to sunlight, light bulbs and fluorescent lamps, but not to invisible infrared.

**Fig 2-6**The LDR in Tinkercad, tested with an ohmmeter. Click the LDR during the simulation for a light slider: far left = dark (180 kΩ), middle = medium light (912 Ω), far right = brightest (506 Ω). The graph: resistance falls as light (lux) rises

Next: transistors and switches →

2.6 Transistor ทรานซิสเตอร์

A transistor is a semiconductor made of P-type and N-type material joined in 3 layers, so it has 3 legs: base (B), collector (C) and emitter (E).
How it works: feed a small current into the base, and the resistance between C and E drops, so a larger current can flow through the transistor.

Type	Structure	Middle layer (base)
NPN	P-type material with N-type on both sides	P
PNP	N-type material with P-type on both sides	N

**Fig 2-7**The two kinds of transistor: (a) NPN structure and symbol, (b) PNP structure and symbol

**Fig 2-8**An NPN transistor (BC547) in Tinkercad: the real part and its pin table, the circuit symbol, wiring straight to the legs, and placing it on a breadboard

💡 Tip

Pin orders differ between transistor models. In Tinkercad, hover over each leg to see whether it is the base, collector or emitter before you wire it.

2.7 Pushbutton switch สวิตช์กดติดปล่อยดับ

A switch makes or breaks a circuit, deciding whether current flows.
A pushbutton (push-on, release-off) is normally open: the circuit is broken. Press it and the circuit is complete; let go and it opens again.

**Fig 2-9**The pushbutton in Tinkercad: legs 1a and 1b are joined inside, and so are 2a and 2b, so the switch must connect a leg on side 1 to a leg on side 2. Wired the wrong way it acts as if always pressed. Easy rule: wire it diagonally

2.8 Slide switch สวิตช์เลื่อน

A slide switch has a sliding lever and 3 legs.
Use all three legs to choose between two paths (a changeover switch), or just the middle leg and one outer leg as a simple on/off switch.

**Fig 2-10**The slide switch: slid left, leg 1 joins the middle leg; slid right, leg 2 joins the middle leg. Wiring 1 and 2 (middle + one side) are correct; wiring 3 (the two outer legs only) is wrong

Next: batteries →

2.9 1.5 V battery แบตเตอรี่ 1.5V

A battery is the basic DC supply for electronic circuits. A single-use battery is called a primary cell and gives 1.5 V per cell.
Ordinary zinc-carbon cells come in sizes AAA, AA, C and D, all 1.5 V. The PP3 has 6 cells inside, so 6 × 1.5 V = 9 V. They supply only a small current but are cheap: good for remote controls and wall clocks.
Alkaline batteries hold 5–10 times more energy and still give 1.5 V per cell, so they suit gadgets that need 300 mA or more, such as MP3 players and digital cameras.
Tinkercad’s 1.5 V battery comes in a holder for 1 to 4 cells, with wires ready to connect, and an optional built-in on/off switch.

**Fig 2-11**Standard battery sizes D, C, AA and AAA give 1.5 V each; the PP3 gives 9 V (photo: rapidonline.com)

**Fig 2-12**The 1.5 V battery in Tinkercad: 1 cell = 1.5 V, 2 = 3 V, 3 = 4.5 V, 4 = 6 V; choose AAA or AA. With Built-in Switch set to yes, remember to slide the switch ON

2.10 Coin / button battery แบตเตอรี่แบบกระดุม

A lithium battery made with lithium and manganese dioxide. It loses very little charge in storage and is small.
Voltages include 1.5, 3, 3.6, 6 and 9 V; 3 V is the most common. Its solid electrolyte gives it a high internal resistance, so it supplies only a small current — fine for watches, calculators, handheld games and small remotes.
The code tells you the size: a CR2032 gives 3 V and is 3.2 mm thick and 20 mm across.

**Fig 2-13**The 3 V coin cell in Tinkercad (red = +, black = −) — the same voltage as two 1.5 V cells. Small and light, but gives little current and costs more. Real ones run flat fast in high-current circuits, but in the Tinkercad simulation they supply unlimited current

2.11 9 V battery แบตเตอรี่ 9V

Tinkercad also has the standard PP3 9 V battery, with a clip and wires.
It first appears lying on its side, which makes wiring awkward. Click rotate until it stands upright with its terminals at the top: the wiring is then neater and easier.

**Fig 2-14**The 9 V battery in Tinkercad: rotate it upright; red = + and black = −. The real battery has + marked on its side, and you connect it with a battery snap

Next: sound and motion →

2.12 Piezo speaker ลำโพงเปียโซ

A speaker turns electrical energy into sound. In most speakers a paper or plastic cone (diaphragm) is fixed to a coil of wire near a permanent magnet: a changing current makes the coil push and pull, and the cone vibrates the air.
A piezo speaker works best between about 1 kHz and 3 kHz. Its sound depends on the size of the piezo disc and its case.
It needs a signal at an audio frequency — a steady DC voltage alone will not make a tune.

**Fig 2-15**The piezo speaker in Tinkercad: a standard piezo, and how it looks while working. Feed it a signal at an audio frequency and it beeps

2.13 DC motor มอเตอร์ไฟตรง

A DC motor turns electrical energy into movement: power it and its shaft spins. Small motors running on +1.5 to +12 V are used in robots and moving projects.
A plain DC motor spins very fast (1,000 rpm or more) but with very little torque (turning force), so a gearbox is added: lower speed, more torque.
Swap the supply wires and the motor turns the other way.

**Fig 2-16**The standard DC motor in Tinkercad. With 3 V the right way round the shaft turns clockwise (positive speed); reversed, anticlockwise (negative speed). On 9 V the speed rises to 17,568 rpm

**Fig 2-17**The hobby gearmotor: a DC motor with a gearbox, giving a lower speed and more torque. The speed reads positive one way round and negative the other

2.14 Vibration motor มอเตอร์สั่น

A special DC motor that vibrates instead of driving a shaft — the buzz in a mobile phone.

**Fig 2-18**Inside a vibration motor: cover, rotating part with an off-centre weight, copper coils, bearing, contacts, shaft, permanent magnet, flexible circuit board and wires

**Fig 2-19**The vibration motor in Tinkercad: real ones run on 3–4.5 V at 0.06 A. Red = +, black = −, and it must be the right way round to vibrate. Over 4.5 V (e.g. 9 V) it is damaged

2.15 Servo motor เซอร์โวมอเตอร์

A servo motor is an actuator that moves to an exact position — for example the steering of a radio-controlled car, or the rudder of a model boat or plane. Those jobs need plenty of torque, so servos are geared.
Standard servos turn through 0–90° or 0–180°; some are modified to turn through a full 360°.
A servo has 3 wires: signal (S), supply (+V) and ground (G).
Tinkercad’s micro servo has two modes: Positional (holds an angle from 0° to 180°) and Continuous (spins through 360°).

**Fig 2-20**Outside a servo motor: the horn, the case, the connector, and its three wires — GND (−), supply (+) and signal (S)

**Fig 2-21**The micro servo in Tinkercad, in an example circuit (9 V battery, LM7805 regulator, LM556 timer). Supply 6 V at most; choose Positional (0–180°) or Continuous (360°)

Tinkercad has many more parts. The ones you need are introduced in the chapters that use them.

Next: review →

Parts at a glance

Part	What it does	Polarity?	Watch out for
Resistor	Limits current	No	Choose the right unit (Ω, kΩ, MΩ)
Potentiometer	Adjustable resistance	No	Use the middle leg
LED	Gives light	Yes: anode +, cathode −	Always add a series resistor
Capacitor (non-polarized)	Stores charge	No	Real ones only go up to a few µF
LDR	Resistance falls in light	No	≈2 MΩ dark, a few hundred Ω bright
Transistor (NPN/PNP)	Small base current controls a big C–E current	Yes: B, C, E	Check the pin order
Pushbutton	On only while pressed	—	Wire diagonally
Slide switch	On/off or changeover	—	Use the middle leg
Batteries	DC supply: 1.5 V cells, 3 V coin, 9 V PP3	Yes	Coin cells give little current in real life
Piezo speaker	Sound	Yes	Needs an audio-frequency signal
DC / gear motor	Rotation	Direction depends on it	Reverse the wires to reverse it
Vibration motor	Vibration	Yes	No more than 4.5 V
Servo	Moves to an angle (or spins)	3 wires: S, +V, G	6 V maximum supply

🛠️ Activity · Test the parts in Tinkercad

Each of these repeats a demonstration from the chapter’s figures.

LDR (Fig 2-6): connect an LDR to a multimeter set to resistance. Start the simulation, click the LDR and move the light slider. Record the reading at far left, middle and far right.
Potentiometer (Fig 2-2): measure across the middle leg and one outer leg while you turn the knob, then across the two outer legs. Which reading changes?
Pushbutton (Fig 2-9): build battery → pushbutton → resistor → LED. Wire the button diagonally, then try the same side. What happens each time?
DC motor (Fig 2-16): connect a DC motor to 2 AA cells and note the rpm, then swap the wires, then try a 9 V battery.
Vibration motor (Fig 2-19): run it from 3 AA cells, then from a 9 V battery. Explain what you see.

Check yourself

Chapter 2 of the book is a parts reference without questions, so these are my own, based on its pages.

1. What is the job of a resistor?

2. Does it matter which way round you put a resistor or a non-polarized capacitor?

3. You wire a potentiometer using only its two outer legs. What happens when you turn the knob?

4. An LDR is in a bright room. Its resistance is…

5. What are the three legs of a transistor called?

6. A pushbutton has legs 1a, 1b, 2a and 2b. Which legs are always joined inside the switch?

7. How many volts do three AA cells in a holder give?

8. Why can a CR2032 coin cell seem stronger in Tinkercad than in real life?

9. You swap the two wires on a DC motor. What happens?

10. Which servo type can turn all the way round, again and again?