Post Office Box-Plug Type (Constantan and Manganin Coil) Manufacturer,Supplier and Exporter in India
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Product Code : EL-PLE-10278
Quick Answer: The Post Office Box-Plug Type (Constantan and Manganin Coil) is a plug-type resistance box in a wood box with sixteen non-inductively wound coils and two ratio arms, used with a DC battery to measure resistance between 0.1 and 1111000 ohms.
Last updated: October 2026
Key Features
Sixteen non-inductively wound coils from 1 to 5000 ohms.
Two proportional arms: 10, 100 and 1000 ohms on the 3-Ratio box; 1, 10, 100 and 1000 ohms on the 4-Ratio box.
Infinity gap included.
Two spring keys for battery and galvanometer.
Resistance measurable from 0.1 to 1111000 ohms with a DC battery.
Rectangular brass blocks 12 mm and 14 mm thick, housed in a wood box.
Technical Specifications
| Specification | Value |
|---|---|
| Versions | 3-Ratio and 4-Ratio |
| Main coils | Sixteen: 1, 2, 2, 5, 10, 20, 20, 50, 100, 200, 200, 500, 1000, 2000, 2000, 5000 ohms |
| Ratio arms | 3-Ratio: 10, 100, 1000 ohms; 4-Ratio: 1, 10, 100, 1000 ohms |
| Measuring range | 0.1 to 1111000 ohms |
| Accuracy | Constantan coil +/-0.1%; manganin coil +/-0.05% |
| Brass blocks | Rectangular, 12 mm and 14 mm thick |
| Keys | Two spring keys |
| Case | Wood box |
About This Product
Connected to a DC battery and a galvanometer through its two spring keys, the box measures unknown resistances from 0.1 to 1111000 ohms. Constantan-coil boxes are stated at plus or minus 0.1% accuracy and manganin-coil boxes at plus or minus 0.05%, so the choice of coil sets the precision available. Educational Lab Equipments can supply and export the Post Office Box-Plug Type (Constantan and Manganin Coil) to Oman, Sierra Leone, Australia, Uganda and Seychelles.
Frequently Asked Questions
What is the difference between the constantan and manganin versions?
Both use 12 mm and 14 mm thick rectangular brass blocks. The constantan coil box has an accuracy of +/-0.1%, the manganin coil box +/-0.05%.
What is the difference between the 3-Ratio and 4-Ratio boxes?
Both have the same sixteen coils. The 3-Ratio box has proportional arms with 10, 100 and 1000 ohm coils; the 4-Ratio box adds a 1 ohm coil to each arm.
What range of resistance can be measured?
Resistances between 0.1 and 1111000 ohms can be measured using a DC battery.
Related: Physics Lab Equipments, Resistance Box, Resistance Box Decade Dial Type.
For a quotation on the Post Office Box-Plug Type (Constantan and Manganin Coil), contact Educational Lab Equipments.
