Outputs
Output elements show the result of the circuit to the outside world: sound, motion, light or digits. An incandescent lamp makes light with a filament, a fan moves air, a bell makes sound with a hammer. Most draw more current than a microcontroller pin can give, so they are connected with a transistor or driver. Some run on a constant voltage, others on a signal (PWM).
9 types4 groupsSymbol IEC
Sound
4
Active buzzerSimple beep alert: apply voltage for sound
- Voltage
- 5 V
- Current
- ≤ 30 mA
- Tone
- ≈2.3 kHz
Passive buzzerDifferent tones and melodies: you set the frequency
- Driving
- Square wave (PWM)
- Resonance
- ≈2–4 kHz
- Voltage
- 3–5 V
SpeakerSound, music and speech: carrying the electrical signal into the air
- Impedance
- 8 Ω
- Power
- 0.5 W
- Diameter
- 40 mm
Electric bell (6 V)Producing mechanical sound and seeing a coil circuit that interrupts itself
- Power supply
- 6 V DC
- Current
- ≈0.2–0.5 A
- Mechanism
- Inductor coil + hammer + contact breaker
Motion
3
DC motorContinuous rotation: fan, wheel, pump
- Voltage
- 3–6 V
- Current
- Hundreds of mA
- Speed setting
- PWM
Servo motorMove to and hold an angle: arm, lid, direction
- Voltage
- 4.8–6 V
- Signal
- 50 Hz PWM
- Pulse
- ≈1–2 ms
DC fan (5 V, 40 mm)Cooling a box or moving air at low voltage
- Power supply
- 5 V DC
- Current
- ≈0.1 A
- Size
- 40 mm
Display
1
Light
1
Which one should I choose?
1
2
3
4
5
6
7
If you will study the light and heating behavior of a filament
Non-polarized; its hot and cold resistance differ.
8
If you want direct airflow
The propeller and brushless driver are ready; red positive, black negative.
9
If you want a mechanical sound with a hammer
Inductor coil and breaker contact produce repeated strikes with DC.
Compare9 types · 4 features
| Type | How to drive it | Voltage | Current | Typical use |
|---|---|---|---|---|
| Active buzzer | Give it DC, it beeps | 5 V typical | ≤ 30 mA | Warning beep |
| Passive buzzer | Square wave (PWM) | 3–5 V | By type | Melody, tones |
| Speaker | Audio signal, amp | Depends on amplifier | From amplifier (8 Ω) | Sound, music |
| DC motor | Transistor / MOSFET | 3–6 V (130 type) | Hundreds of mA | Fan, wheel |
| Servo motor | 50 Hz PWM, 1–2 ms | 4.8–6 V | Hundreds of mA | Angle control |
| 7-segment display | Resistor per segment | ≈2 V / segment | ≈10 mA / segment | Don't show digits |
| Incandescent lamp (E10, 6 V 0.1 A) | 6 V DC / AC, suitable driver | 6 V | 0.1 A; more at start-up | Light, resistance change with heat |
| DC fan (5 V, 40 mm) | 5 V DC, polarized | 5 V | ≈0.1 A | Airflow, cooling |
| Electric bell (6 V) | 6 V DC, suitable driver | 6 V | ≈0.2–0.5 A | Mechanical sound |
Typical values; vary by model.