Decade Box

Core Summary

A decimal box is a precision reference source that connects multiple "decimal" standard components together and uses a dial to select values. For example, a decimal resistance box, when dialed to 1.234 kΩ, can provide a resistance close to that value, which is used to verify multimeters, sensors, or meters. It is commonly used in the field and in the laboratory and is a type of standard device with a low entry threshold for calibration work.

I. What Does It Solve

Calibrating a meter does not necessarily require moving the entire set of standard sources. A decimal box uses a dial to directly provide a known standard value, making the operation simple and the reading intuitive. It is suitable for spot checks and teaching, and also for "bringing the standard to the field" for quick comparisons.

II. Common Types

• **Resistance Box**: This is used frequently and covers multiple ranges from ohms to megohms, making it convenient for verifying multimeters and shunts.

• **Capacitance Box / Inductance Box**: Provides standard capacitance and inductance values for verification in corresponding circuits. Time Electronics' 1053 and 1067 are examples of this type.

• **All-in-One**: Some combination boxes integrate multiple standard values, allowing for fewer items to be carried in the field.

III. When Using, Pay Attention

• Be aware of the allowed current/voltage upper limits, as exceeding them can damage the standard components. Calculate carefully before wiring.

• Long-term accuracy is maintained through regular inspection, so do not treat it as calibration-free. It should be sent for inspection when due.

• Lead resistance and contact resistance can introduce errors, which should be taken into account in high-precision applications. If necessary, use the four-wire method.