1Output arm (horn) · 0–180°
2Output shaft (gear)
3Gear cover
4Body and mounting ears · 22.8 × 12.2 mm
5Wires: brown GND, red +5 V, orange signal

Blue plastic body, output shaft and horn on top, brown-red-orange wire
SG90: ≈ 23 × 12.2 × 29 mm, ≈ 9 g

Outputs

Servo motor

In simple terms

What is this?

A small motor that turns to the angle you want and stays there; a hand that brings its arm wherever you want.

What is it for?

Holds things like a robot arm, a flap or a lock at a set angle.

Where do you see it?

Steering in remote-controlled vehicles, small camera pan units.

How do you spot it?

A small rectangular plastic box with a geared shaft on top and a three-colour wire.

Caution:

Brown is negative, red is positive, orange is signal; connect the wires accordingly and don't force the shaft to turn.

Technical definition

A motor with a DC motor, gearbox, position potentiometer and control circuit inside. It turns to a certain angle according to the width of the pulse arriving on the signal line and tries to stay there. Micro servos like the SG90 turn about 180°.

Voltage4.8–6 V

Signal50 Hz PWM

Pulse≈1–2 ms

Schematic symbol Same in IEC and ANSI

IEC 60617: the drawing style used in Türkiye and Europe.

Pins 3

1Brown wire: GNDCommon negative of the supply and control circuitGND

2Red wire: V+4.8–6 V; power it from a separate sourceV+

3Orange wire: signal50 Hz, pulses ≈1–2 ms widePWM

Features typical

Voltage: 4.8–6 V
Signal: 50 Hz (20 ms period)
Pulse width: ≈1–2 ms (0.5–2.5 ms depending on model)
Center position: ≈1.5 ms
Rotation angle: ≈180°
Torque: ≈1.8 kg·cm (4.8 V)
Speed: ≈0.1 s / 60°
Example part: SG90 micro servo

Common mistakes

Powering it from a microcontroller boardA servo draws hundreds of mA while moving. Power it from a separate source, not from the board's 5 V pin.

Not joining the groundsEven if the servo is powered from a separate source, its GND must be shared with the source and the control circuit; otherwise the signal is not understood.

Forcing it by handPlastic gears break easily. Do not try to turn the servo’s horn by hand.

Test with a multimeter

Test whether this part is good with the multimeter on the measurement screen.

Take a measurement

Where it is used

Robot armLid or lock openingSteering in an RC carCamera rotation