Resistor 3W 4.7 ohm

The Resistor 3W 4.7 ohm is a fixed power resistor with a low resistance of 4.7 Ω and a power rating of 3 W. Its higher wattage lets it carry currents of up to about 0.8 A that would burn out a standard 0.25 W resistor, so it is used for current limiting, constant-current sources, low-voltage test loads and repairs of power and audio circuits.

Resistor 3W 4.7 ohm Specifications

• Resistance: 4.7 Ω (also written 4R7)
• Power rating: 3 W
• Maximum continuous current: about 0.8 A at the full 3 W rating (I = √(P / R))
• Maximum voltage across it at 3 W: about 3.75 V
• Type: fixed power resistor, through-hole
• Quantity: 1 piece

Resistor 3W 4.7 ohm Applications

• Setting the current of an LM317 constant-current source: 1.25 V / 4.7 Ω ≈ 266 mA
• Current limiting for power LEDs, small lamps and DC motors
• Low-voltage test loads: 3.3 V across 4.7 Ω draws about 0.7 A and dissipates about 2.3 W
• Low-power dummy load for testing small audio amplifiers
• Replacement part in amplifier and power supply repairs

What's in the Box

• 1 × 4.7 Ω 3 W resistor

Tip: At full rating the resistor gets very hot. For long life run it at about half its rated power, keep some air around the body and keep it away from plastic parts and wire insulation. Check the power with P = I² × R: 0.5 A through 4.7 Ω is about 1.2 W.

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