Film Resistor - Carbon Film Resistor
Carbon film resistors are fixed axial resistors made by depositing a thin carbon film onto a ceramic carrier to restrict the flow of electrical current. They are highly reliable, economical, and widely used in general-purpose electronic circuits.
Material Construction and How It Works
- Ceramic Core: A high-grade ceramic rod acts as the stable base.
- Carbon Film: A pure carbon crystalline film is deposited onto the rod.
- Helical Groove: A spiral groove is cut into the film to adjust the precise resistance value.Protective Coating: The finished element is coated with baked epoxy or resin for insulation.
- Voltage Range: Usually handles lower maximum voltages than metal film variants.
- Power Ratings: Commonly available in 1/8W, 1/4W, 1/2W, 1W, and 2W variations.
- Standard Tolerances: Typically ±5% (Gold band), which is standard for general circuits.
Quick Multiplier Guide
- R = Multiply by 1 (or acts as a decimal point)
- K = Multiply by 1,000
- M = Multiply by 1,000,000
Step-by-Step Conversion & Examples
1. The Letter "R" (Ohms)
If the letter R is at the end, it just means ohms. If it is between two numbers, replace the R with a decimal point.
- 47R = 47 Ω
- 0R5 = 0.5 Ω
- 2R2 = 2.2 Ω
- 100R = 100 Ω
2. The Letter "K" (Kilo-ohms)
Multiply the number by 1,000. If the K is between numbers, replace it with a decimal point and multiply by 1,000.
- 1K = 1 × 1,000 = 1,000 Ω (1 kΩ)
- 4K7 = 4.7 × 1,000 = 4,700 Ω (4.7 kΩ)
- 10K = 10 × 1,000 = 10,000 Ω (10 kΩ)
- 680K = 680 × 1,000 = 680,000 Ω (680 kΩ)
3. The Letter "M" (Mega-ohms)
Multiply the number by 1,000,000. If the M is between numbers, replace it with a decimal point and multiply by 1,000,000.
- 1M = 1 × 1,000,000 = 1,000,000 Ω (1 MΩ)
- 2M2 = 2.2 × 1,000,000 = 2,200,000 Ω (2.2 MΩ)
- 10M = 10 × 1,000,000 = 10,000,000 Ω (10 MΩ