Lacquer coating and color bands · red-red-brown-gold = 220 Ω 5%Tolerance band (gold = 5%)Pins (tinned copper)

Beige body, four color rings (red-red-brown-gold = 220 Ω ±5%), two axial pins, actual scale
Body ≈ 6.3 × 2.4 mm, leg ≈ 28 mm

Resistors

Carbon film resistor

In simple terms

What is this?

A narrow pipe the electricity passes through. As the pipe narrows, the flow decreases; the resistance value shows how narrow it is.

What is it for?

Limits the current; placed in front of an LED so it does not burn out, and it can also divide voltage.

Where do you see it?

Small cylinders on the board of cheap toys and radios.

How do you spot it?

Small cylindrical body with two pins; it has four colored rings on it.

Caution:

Don't start reading the bands from the reverse end, and don't exceed its power rating; an overloaded resistor heats up.

Technical definition

A fixed resistor made by coating a thin carbon layer on a ceramic rod. Its value is read from four color bands on the body. Being cheap, it is found in most hobby circuits.

Power0.25 W

Tolerance±5%

Range1 Ω – 10 MΩ

Schematic symbol IEC and ANSI differ

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

Pins 2

1Pin 1Has no direction, fits either way1

2Pin 2Has no direction, fits either way2

Color code reader

220Ω

±5% · red · red · brown · gold

Band 1Digit 1

Band 2Digit 2

Band 3Multiplier

Band 4Tolerance

Reading direction: hold it with the tolerance band (usually gold) on the right. If you are color-blind, read the value from the text above.

Features typical

Power: 0.25 W (70 °C)
Tolerance: ±5% (gold band)
Value range: 1 Ω – 10 MΩ
Value series: E24
Max. operating voltage: 250 V
Operating temperature: −55 … +155 °C
Example part: CF 1/4 W (CFR-25)

Common mistakes

Reading the bands in reverseHold the gold or silver tolerance ring on the right and read from the left. If unsure, measure with a multimeter.

Not calculating the powerCalculate dissipated power with P = I² × R. A resistor approaching the 0.25 W limit heats up and darkens; pick the next higher power rating.

Measuring in-circuitResistance is not measured correctly in a powered circuit. Cut the power and lift one leg out of the circuit to measure.

Test with a multimeter

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

Take a measurement

Where it is used

Limiting LED currentVoltage dividerPull-up / pull-downTransistor base resistor

Try it in the Lab