470 kΩ resistor color code

Where you'll meet it

Measuring a lithium cell with a bare ESP8266

The ESP8266 chip measures only 0 to 1.0 V on its ADC pin. Boards such as the Wemos D1 mini have a divider in front of it, but a bare module such as the ESP-12 does not. To watch the lithium cell that powers a project, 470 kΩ from the cell's plus to the ADC pin and 100 kΩ from the ADC pin to ground stretch the range to 5.7 V.

V_out = 5.7 V × 100 kΩ / (470 kΩ + 100 kΩ) = 1.0 V

A full cell at 4.2 V gives 4.2 V × 100 kΩ / 570 kΩ ≈ 0.74 V, and an empty one at about 3.0 V gives about 0.53 V: the whole range fits under 1.0 V.

The pair draws at most 5.7 V / 570 kΩ = 0.01 mA, tiny next to what the module itself uses.

In code, multiply the voltage at the ADC pin by 5.7 (that is 570 kΩ / 100 kΩ) to get the cell voltage.

The module still runs from its 3.3 V regulator; the divider only measures the cell, and the cell's minus is the circuit's GND. Resistor tolerances and the ESP8266's own ADC error shift the result by a few percent, so calibrate against a meter. Do not add this divider to a Wemos D1 mini or a NodeMCU: they already have 220 kΩ and 100 kΩ on A0.

On SMD parts

Look for 474 or 4703

• 474474 = 47 × 10⁴ = 470,000 Ω (3-digit code).
• 47034703 = 470 × 10³ = 470,000 Ω (4-digit code, usually ±1% parts).

There is no EIA-96 code, because 470 kΩ is not an E96 value (the nearest E96 values are 464 kΩ and 475 kΩ).

Check it with a meter

Read 446.5–493.5 kΩ

1. Take the resistor out of the circuit.
2. Set the meter to Ω, range 2 MΩ (or auto).
3. Touch one probe to each lead. Keep your fingers off the metal: your body is a resistor too. At 470 kΩ this matters a lot: with a finger on each lead the meter measures you as well, and the reading drops.
4. Anything from 446.5 to 493.5 kΩ is a good ±5% part. A 5-band ±1% part should read 465.3 to 474.7 kΩ.

A meter has a small error of its own, so a reading a hair outside the range does not prove the part is bad. Measure again with firm contact before you swap it.