Real View
Resistor (1/4 W carbon film)Through-hole carbon film resistor · YAGEO CFR-25
Set a current, divide a voltage, and keep within the power.
Manufacturer-referenced
YAGEO · CFR-25JB-52-1K
Axial (CFR-25)CFR series product specification · 2 Sep 2022 · CFR-25 (1/4 W)A resistor opposes current in a fixed proportion to the voltage across it: V = I × R (Ohm’s law). It turns the electrical energy it takes, P = V × I = I² × R, into heat, so every resistor has a power rating as well as a resistance. Resistors set currents (an LED’s series resistor), divide voltages (a sensor or reference divider), pull signals to a defined level and form timing networks with capacitors. They have no polarity: either end can face the supply. This page uses the YAGEO CFR-25, a 1/4 W carbon film resistor in an axial package with colour bands. It carries full power up to 70 °C ambient, may never see more than √(P × R) or 250 V, and changes by up to −500 to +350 ppm/°C below 100 kΩ.
2Physical pins
CFR-25JB-52-1KAxial (CFR-25)
Manufacturer-referencedYAGEO
Pin diagram
Select a pin to explore its connection
Highlight
Resistor (1/4 W carbon film)Axial (CFR-25)Top view · no polarity
Click a lead or use the arrow keys. Top view · no polarity
PIN 1 · Terminals · no polarity
Terminal 11
Function
One end of the resistive film. A resistor has no polarity: either end can face the supply.
How to connect
Connect in series with the part whose current it limits, or as the top of a divider.
Electrical note
Power P = I² × R is shared by the whole body; the leads carry heat away.
PIN 2 · Terminals · no polarity
Terminal 22
Function
The other end of the film, identical to terminal 1.
How to connect
Connect to the rest of the circuit or toward ground.
Electrical note
Keep the body clear of the board when it runs warm.
Key specifications
Pick the resistance from the job (current, divider ratio or pull-up), then check the power, I² × R, against 1/4 W derated for the ambient, and the voltage against √(P × R) and 250 V.
Power rating0.25 W at 70 °C ambient
Maximum working voltage250 V · and never above √(P × R)
Resistance range1 Ω–10 MΩ E24 values · ±2 % or ±5 %
Operating range−55 to +155 °C
Package details
CFR-25JB-52-1K · Axial (CFR-25)
| Property | Details |
|---|---|
| Manufacturer | YAGEO |
| Part number | CFR-25JB-52-1K |
| Package | Axial (CFR-25) |
| Connections | 2 pins |
| Mounting | Through-hole |
| Lead pitch | 10.16 mm (M-formed 10.0 ± 1 mm) |
| Package code | CFR-25 |
| Thermal reference | About 340 °C/W in free air (from the derating curve) |
Selected part
Manufacturer scope and page conventions
Manufacturer specifications 6 parameters
Scroll sideways to see all columns.
| Parameter | Value | Conditions / notes |
|---|---|---|
| Reference | YAGEO CFR series, product specification 2 Sep 2022 | CFR-25 column (1/4 W) |
| Construction | Carbon film on a ceramic core, helically trimmed | Lacquer coated, colour bands |
| Default part | CFR-25JB-52-1K | 1 kΩ, ±5 % (J), bulk |
| Polarity | None | Pins 1 and 2 are interchangeable |
| Footprint | RES40 · 10.16 mm (0.4 in) between pads | Leads formed for a board; YAGEO M-forming is 10.0 ± 1 mm |
| Values | E24 series, 1 Ω to 10 MΩ | ±2 % (G) or ±5 % (J) |
No specifications match. Try a parameter name or a unit.
The colour code is the same for every through-hole resistor; the power rating is not, so check the body size.
Ratings
CFR-25 · 1/4 W
Manufacturer specifications 7 parameters
Scroll sideways to see all columns.
| Parameter | Value | Conditions / notes |
|---|---|---|
| Power rating | 0.25 W | At 70 °C ambient |
| Derating | 100 % up to 70 °C, linearly to 0 % at 155 °C | Ambient temperature |
| Maximum working voltage | 250 V | And never above the rated continuous working voltage √(P × R) |
| Maximum overload voltage | 500 V | Short-time overload test limit |
| Dielectric withstanding voltage | 500 V for 60 s | V-block, no breakdown |
| Operating temperature | −55 to +155 °C | Recommended range |
| Peak pulse power | 66 W up to 10 µs, about 0.58 W at 1 s | Single pulse, from the pulse diagram |
No specifications match. Try a parameter name or a unit.
RCWV = √(P × R): a 1 kΩ part reaches its power at 15.8 V; above 250 kΩ the 250 V limit applies first.
Temperature coefficient
Maximum change per °C
Manufacturer specifications 5 parameters
Scroll sideways to see all columns.
| Parameter | Value | Conditions / notes |
|---|---|---|
| Below 100 kΩ | −500 to +350 ppm/°C | Carbon film usually falls slightly as it warms |
| 100 kΩ to 1 MΩ | −700 to 0 ppm/°C | Maximum |
| 1 MΩ to 10 MΩ | −1500 to 0 ppm/°C | Maximum |
| Example | 1 kΩ at −300 ppm/°C heated by 50 °C | R = 1000 × (1 − 0.0003 × 50) = 985 Ω |
| Thermal resistance | About 340 °C/W in free air | (155 − 70) °C / 0.25 W |
No specifications match. Try a parameter name or a unit.
Use metal film (±50 ppm/°C or better) where a divider must stay accurate over temperature.
Endurance and overload tests
IEC 60115-1 · allowed resistance change
Manufacturer specifications 8 parameters
Scroll sideways to see all columns.
| Test | Condition | Allowed change |
|---|---|---|
| Short-time overload (4.13) | 2.5 × RCWV for 5 s, never above 500 V | ±(0.75 % + 0.05 Ω) |
| Periodic-pulse overload (4.39) | 4 × RCWV (or Umax), 10 000 cycles of 1 s on, 25 s off | ±(1 % + 0.05 Ω) |
| Endurance at 70 °C (4.25) | RCWV for 1000 h (1.5 h on, 0.5 h off) | ±(3 % + 0.05 Ω) |
| Damp heat (4.24) | 40 °C, 90–95 % RH, 56 days at 0.1 × RCWV | ±(3 % + 0.05 Ω) |
| Temperature cycling (4.19) | −55 °C ↔ +155 °C, 5 cycles | ±(1 % + 0.05 Ω) |
| Soldering heat (4.18) | 260 °C for 10 s, 3 mm from the body | ±(1 % + 0.05 Ω) |
| Insulation resistance (4.6) | V-block, 60 s | > 1000 MΩ |
| Robustness of terminations (4.16) | Pull along the leads for 10 s | ≥ 24.5 N (2.5 kg) |
No specifications match. Try a parameter name or a unit.
These are qualification tests of the part, not normal operating conditions.
Colour code
Four-band through-hole resistors
Manufacturer specifications 12 parameters
Scroll sideways to see all columns.
| Colour | Digit | Multiplier | Tolerance |
|---|---|---|---|
| Black | 0 | × 1 | — |
| Brown | 1 | × 10 | ±1 % |
| Red | 2 | × 100 | ±2 % |
| Orange | 3 | × 1 k | — |
| Yellow | 4 | × 10 k | — |
| Green | 5 | × 100 k | ±0.5 % |
| Blue | 6 | × 1 M | ±0.25 % |
| Violet | 7 | × 10 M | ±0.1 % |
| Grey | 8 | — | — |
| White | 9 | — | — |
| Gold | — | × 0.1 | ±5 % |
| Silver | — | × 0.01 | ±10 % |
No specifications match. Try a parameter name or a unit.
Read from the end nearest a band: 220 Ω is red–red–brown–gold, 1 kΩ brown–black–red–gold, 10 kΩ brown–black–orange–gold.
Two everyday circuits
LED current limit and a voltage divider
Manufacturer specifications 5 parameters
Scroll sideways to see all columns.
| Parameter | Value | Conditions / notes |
|---|---|---|
| LED from 5 V, red (Vf 1.85 V) | 220 Ω → 14.3 mA | (5 − 1.85) / 220 |
| Power in that resistor | 45 mW | 0.0143² × 220; 18 % of 1/4 W |
| Divider from 9 V | 10 kΩ over 4.7 kΩ → 2.88 V | 9 × 4.7 / (10 + 4.7) |
| Divider current and power | 0.61 mA · 3.8 mW in the 10 kΩ | Loading the output lowers it |
| What burns | 100 Ω across 9 V: 810 mW | 3.2 × the rating; the film opens within seconds |
No specifications match. Try a parameter name or a unit.
ProTech’s resistor example runs all of these, including the burnout.
Package
CFR-25JB-52-1K · Axial (CFR-25)
Manufacturer specifications 5 parameters
Scroll sideways to see all columns.
| Parameter | Value | Conditions / notes |
|---|---|---|
| Body length | 6.3 ± 0.5 mm | CFR-25 |
| Body diameter | 2.4 ± 0.2 mm | Lacquered, colour bands |
| Leads | Ø 0.55 ± 0.05 mm, 28 ± 2 mm long | Tinned copper |
| Formed for a board | 10.0 ± 1 mm between bent leads | YAGEO M type |
| Footprint | RES40: pads 1 and 2, 10.16 mm apart | 1.778 mm round pads, 0.762 mm drill · Through-hole |
No specifications match. Try a parameter name or a unit.
Leave 1–2 mm between the body and the board for parts that run warm.
Connections by function
Select a pin for its function, connection guidance and electrical notes.
Terminals · no polarity2 pins
Resistor (1/4 W carbon film) at a glance
Follow the labeled connections and functional stages
How it works
3 stages · Explore one step at a time
Read the colour bands
Four bands: two digits, a multiplier and the tolerance. Brown–black–red–gold is 10 × 100 = 1 kΩ, ±5 %.
Apply Ohm’s law
The current through it is V / R, the same at both ends. In a series chain the voltages add; in a divider the output is Vin × R2 / (R1 + R2).
Check the heat
P = I² × R. The CFR-25 takes 1/4 W up to 70 °C ambient, falling linearly to zero at 155 °C. Above that the film overheats, drifts and finally opens.
Step 1 of 3
Resistor (1/4 W carbon film) in a circuit
An LED current limit at 5 V and a divider at 9 V.
Connect it, step by step
Follow the component values and pin connections
Limit a current
The resistor takes the voltage the LED does not: 5 − 1.85 = 3.15 V across 220 Ω.
Divide a voltage
Two resistors in series share the supply in proportion to their values.
Check the power
I² × R for each resistor, against 1/4 W derated for the ambient.
Inside Resistor (1/4 W carbon film)
Ceramic core, carbon film, helical trim, end caps and leads.
Explore the circuit
Select a stage to see its role and connections
Carbon film
A thin carbon layer on a ceramic rod is the resistive element.
Helical trim
A spiral groove cut into the film lengthens the current path until the value is reached.
Caps and lacquer
Pressed end caps join the leads; the lacquer coat insulates and carries the colour bands.
Selected packageAxial (CFR-25)CFR-25JB-52-1K
Physical connections2 pinsPackage-specific numbering
Reference collection8 tables48 parameters & pin functions
Pin reference
Signal names, electrical functions and connection guidance
Physical pin numbers2 pins
Scroll within the table to see all columns and rows.
| Pin | Signal | Type | Function & connection |
|---|---|---|---|
| 1 | Terminal 1 | One end of the resistive film. A resistor has no polarity: either end can face the supply.Connection guidanceConnect in series with the part whose current it limits, or as the top of a divider. Power P = I² × R is shared by the whole body; the leads carry heat away. | |
| 2 | Terminal 2 | The other end of the film, identical to terminal 1.Connection guidanceConnect to the rest of the circuit or toward ground. Keep the body clear of the board when it runs warm. |
No pins match these filters. Try another signal name or reset the filters.
Selected part
Manufacturer scope and page conventions
Manufacturer-referenced values6 parameters
Scroll within the table to see all columns and rows.
| Parameter | Value | Conditions / notes |
|---|---|---|
| Reference | YAGEO CFR series, product specification 2 Sep 2022 | CFR-25 column (1/4 W) |
| Construction | Carbon film on a ceramic core, helically trimmed | Lacquer coated, colour bands |
| Default part | CFR-25JB-52-1K | 1 kΩ, ±5 % (J), bulk |
| Polarity | None | Pins 1 and 2 are interchangeable |
| Footprint | RES40 · 10.16 mm (0.4 in) between pads | Leads formed for a board; YAGEO M-forming is 10.0 ± 1 mm |
| Values | E24 series, 1 Ω to 10 MΩ | ±2 % (G) or ±5 % (J) |
No specifications match. Try a parameter name or a unit.
The colour code is the same for every through-hole resistor; the power rating is not, so check the body size.
Ratings
CFR-25 · 1/4 W
Manufacturer-referenced values7 parameters
Scroll within the table to see all columns and rows.
| Parameter | Value | Conditions / notes |
|---|---|---|
| Power rating | 0.25 W | At 70 °C ambient |
| Derating | 100 % up to 70 °C, linearly to 0 % at 155 °C | Ambient temperature |
| Maximum working voltage | 250 V | And never above the rated continuous working voltage √(P × R) |
| Maximum overload voltage | 500 V | Short-time overload test limit |
| Dielectric withstanding voltage | 500 V for 60 s | V-block, no breakdown |
| Operating temperature | −55 to +155 °C | Recommended range |
| Peak pulse power | 66 W up to 10 µs, about 0.58 W at 1 s | Single pulse, from the pulse diagram |
No specifications match. Try a parameter name or a unit.
RCWV = √(P × R): a 1 kΩ part reaches its power at 15.8 V; above 250 kΩ the 250 V limit applies first.
Temperature coefficient
Maximum change per °C
Manufacturer-referenced values5 parameters
Scroll within the table to see all columns and rows.
| Parameter | Value | Conditions / notes |
|---|---|---|
| Below 100 kΩ | −500 to +350 ppm/°C | Carbon film usually falls slightly as it warms |
| 100 kΩ to 1 MΩ | −700 to 0 ppm/°C | Maximum |
| 1 MΩ to 10 MΩ | −1500 to 0 ppm/°C | Maximum |
| Example | 1 kΩ at −300 ppm/°C heated by 50 °C | R = 1000 × (1 − 0.0003 × 50) = 985 Ω |
| Thermal resistance | About 340 °C/W in free air | (155 − 70) °C / 0.25 W |
No specifications match. Try a parameter name or a unit.
Use metal film (±50 ppm/°C or better) where a divider must stay accurate over temperature.
Endurance and overload tests
IEC 60115-1 · allowed resistance change
Manufacturer-referenced values8 parameters
Scroll within the table to see all columns and rows.
| Test | Condition | Allowed change |
|---|---|---|
| Short-time overload (4.13) | 2.5 × RCWV for 5 s, never above 500 V | ±(0.75 % + 0.05 Ω) |
| Periodic-pulse overload (4.39) | 4 × RCWV (or Umax), 10 000 cycles of 1 s on, 25 s off | ±(1 % + 0.05 Ω) |
| Endurance at 70 °C (4.25) | RCWV for 1000 h (1.5 h on, 0.5 h off) | ±(3 % + 0.05 Ω) |
| Damp heat (4.24) | 40 °C, 90–95 % RH, 56 days at 0.1 × RCWV | ±(3 % + 0.05 Ω) |
| Temperature cycling (4.19) | −55 °C ↔ +155 °C, 5 cycles | ±(1 % + 0.05 Ω) |
| Soldering heat (4.18) | 260 °C for 10 s, 3 mm from the body | ±(1 % + 0.05 Ω) |
| Insulation resistance (4.6) | V-block, 60 s | > 1000 MΩ |
| Robustness of terminations (4.16) | Pull along the leads for 10 s | ≥ 24.5 N (2.5 kg) |
No specifications match. Try a parameter name or a unit.
These are qualification tests of the part, not normal operating conditions.
Colour code
Four-band through-hole resistors
Manufacturer-referenced values12 parameters
Scroll within the table to see all columns and rows.
| Colour | Digit | Multiplier | Tolerance |
|---|---|---|---|
| Black | 0 | × 1 | — |
| Brown | 1 | × 10 | ±1 % |
| Red | 2 | × 100 | ±2 % |
| Orange | 3 | × 1 k | — |
| Yellow | 4 | × 10 k | — |
| Green | 5 | × 100 k | ±0.5 % |
| Blue | 6 | × 1 M | ±0.25 % |
| Violet | 7 | × 10 M | ±0.1 % |
| Grey | 8 | — | — |
| White | 9 | — | — |
| Gold | — | × 0.1 | ±5 % |
| Silver | — | × 0.01 | ±10 % |
No specifications match. Try a parameter name or a unit.
Read from the end nearest a band: 220 Ω is red–red–brown–gold, 1 kΩ brown–black–red–gold, 10 kΩ brown–black–orange–gold.
Two everyday circuits
LED current limit and a voltage divider
Manufacturer-referenced values5 parameters
Scroll within the table to see all columns and rows.
| Parameter | Value | Conditions / notes |
|---|---|---|
| LED from 5 V, red (Vf 1.85 V) | 220 Ω → 14.3 mA | (5 − 1.85) / 220 |
| Power in that resistor | 45 mW | 0.0143² × 220; 18 % of 1/4 W |
| Divider from 9 V | 10 kΩ over 4.7 kΩ → 2.88 V | 9 × 4.7 / (10 + 4.7) |
| Divider current and power | 0.61 mA · 3.8 mW in the 10 kΩ | Loading the output lowers it |
| What burns | 100 Ω across 9 V: 810 mW | 3.2 × the rating; the film opens within seconds |
No specifications match. Try a parameter name or a unit.
ProTech’s resistor example runs all of these, including the burnout.
Package
CFR-25JB-52-1K · Axial (CFR-25)
Manufacturer-referenced values5 parameters
Scroll within the table to see all columns and rows.
| Parameter | Value | Conditions / notes |
|---|---|---|
| Body length | 6.3 ± 0.5 mm | CFR-25 |
| Body diameter | 2.4 ± 0.2 mm | Lacquered, colour bands |
| Leads | Ø 0.55 ± 0.05 mm, 28 ± 2 mm long | Tinned copper |
| Formed for a board | 10.0 ± 1 mm between bent leads | YAGEO M type |
| Footprint | RES40: pads 1 and 2, 10.16 mm apart | 1.778 mm round pads, 0.762 mm drill · Through-hole |
No specifications match. Try a parameter name or a unit.
Leave 1–2 mm between the body and the board for parts that run warm.
No matching rowsTry a pin name, parameter, unit or test condition, or reset the filters.
Current limiting
Set the current of LEDs, transistor bases and optocouplers: R = (V − Vdrop) / I.
Manufacturer application guideVoltage dividers
Scale a voltage for an ADC input or make a reference: Vout = Vin × R2 / (R1 + R2).
Manufacturer application guidePull-ups and pull-downs
Give an input a defined level when a switch or open-collector output is off; 4.7–10 kΩ is typical.
Manufacturer application guideTake it into ProTech
Find Resistor (1/4 W carbon film) in the Components Library to place its schematic symbol and connect its pins.
Reference page · circuit simulation model not yet availableOpen ProTech