0.25 W 1% Metal Film Resistor Series – Support Documentation
Overview
This series of metal film resistors provides precision resistance values in a compact 0.25 W through-hole package. With ±1% tolerance, low noise, and stable performance across a wide temperature range, these resistors are suitable for general-purpose electronics, precision analogue circuits, and educational prototyping.
Key Features
- Resistance values from 1 Ω to 1 MΩ
- Power rating: 0.25 W (¼ W)
- Tolerance: ±1%
- Temperature coefficient: ±50 ppm/°C typical
- Low noise and high stability compared to carbon film resistors
- Axial, through-hole design for easy prototyping
Specifications
| Parameter | Value |
|---|---|
| Power Rating | 0.25 W at 70 °C |
| Tolerance | ±1% |
| Max Working Voltage | ≈250 V |
| Max Overload Voltage | ≈500 V |
| Temperature Coefficient | ±50 ppm/°C typical |
| Operating Temperature | –55 °C to +155 °C |
| Body Size | ~6.3 mm × 2.3 mm (MF25 standard) |
Available Values and Colour Codes
| Value | Resistance (Ω) | Colour Code (5-band, 1% tolerance) |
|---|---|---|
| 1R | 1 Ω | Brown – Black – Black – Gold – Brown |
| 10R | 10 Ω | Brown – Black – Black – Red – Brown |
| 68R | 68 Ω | Blue – Grey – Black – Gold – Brown |
| 100R | 100 Ω | Brown – Black – Black – Black – Brown |
| 220R | 220 Ω | Red – Red – Black – Black – Brown |
| 330R | 330 Ω | Orange – Orange – Black – Black – Brown |
| 470R | 470 Ω | Yellow – Violet – Black – Black – Brown |
| 680R | 680 Ω | Blue – Grey – Black – Black – Brown |
| 1K | 1,000 Ω | Brown – Black – Black – Brown – Brown |
| 1K8 | 1,800 Ω | Brown – Grey – Black – Brown – Brown |
| 2K2 | 2,200 Ω | Red – Red – Black – Brown – Brown |
| 3K6 | 3,600 Ω | Orange – Blue – Black – Brown – Brown |
| 4K7 | 4,700 Ω | Yellow – Violet – Black – Brown – Brown |
| 5K6 | 5,600 Ω | Green – Blue – Black – Brown – Brown |
| 10K | 10,000 Ω | Brown – Black – Black – Red – Brown |
| 15K | 15,000 Ω | Brown – Green – Black – Red – Brown |
| 100K | 100,000 Ω | Brown – Black – Black – Orange – Brown |
| 1M | 1,000,000 Ω | Brown – Black – Black – Yellow – Brown |
Typical Applications
- LED current limiting
- Voltage divider networks
- Analogue signal conditioning
- Pull-up / pull-down in digital logic
- Biasing for amplifiers and transistor stages
- General educational and prototyping use
Usage Notes
- Ensure resistor dissipation does not exceed 0.25 W—otherwise use a higher wattage type.
- For high-voltage circuits, ensure working voltage ratings are respected.
- Use resistors with clearance above the PCB in warm environments.
- Choose values carefully for precision divider applications—1% tolerance helps minimise error.
Troubleshooting
| Issue | Possible Cause | Solution |
|---|---|---|
| Resistor runs hot | Excess current / undervalued resistance | Increase resistance or use 0.5 W / 1 W resistor |
| Circuit not behaving as expected | Wrong value chosen or misread colour code | Verify with a multimeter before use |
| Resistance drifting | High ambient temperature | Keep below rated 155 °C; avoid mounting near heat sinks or regulators |
FAQs
- What does 1% mean?
The resistor’s actual value will be within ±1% of its nominal resistance. - Can these be used in AC and DC circuits?
Yes, as long as ratings are respected. - Are these suitable for breadboard use?
Yes, axial leads fit standard breadboards. - What happens if I exceed 0.25 W?
Excess power causes overheating, drift, and eventual failure (often open circuit).
Safety Considerations
- Do not exceed rated power or maximum voltage
- Store and handle in a dry environment to prevent corrosion
- Keep away from high humidity to avoid resistance drift
- For power or mains use, select higher wattage and safety-rated resistors