Post Office Box-Plug Type (Constantan & Manganin Coil) Manufacturer,Supplier and Exporter
Product Code : SEL-PLE-10171
Quick Answer: This plug-type Post Office Box puts a complete Wheatstone bridge in a polished wooden case, with ratio arms of 10, 100 and 1000 Ω, 16 resistance coils from 1 to 5000 Ω and two spring keys.
Last updated: October 2026
Key Features
- Polished wooden box with hinged lid and panel printed with circuit connections
- Three pairs of ratio arms, each 10, 100 and 1000 Ω
- Resistance arm of 16 coils from 1 to 5000 Ω, with infinity plug
- Double silk covered coils, wound non-inductively, negligible temperature coefficient
- Two spring keys with special contacts for battery and galvanometer
- Coil accuracy: 100 to 500 Ω ± 0.05%; resistance coils ± 0.1%
Technical Specifications
| Specification | Value |
|---|---|
| Type | Plug type, constantan and manganin coils |
| Ratio arms | Three pairs, each 10, 100, 1000 Ω |
| Resistance arm | 16 coils, 1 to 5000 Ω, with infinity plug |
| Coil winding | Double silk covered, non-inductive |
| Keys | Two spring keys (battery and galvanometer) |
| Accuracy | 100 to 500 Ω coils ± 0.05%; resistance coils ± 0.1% |
About This Product
Students use the Post Office Box to find an unknown resistance by balancing a bridge: the ratio arms set the multiplier, plugs are pulled from the resistance arm, and the galvanometer key is pressed until no deflection is seen. The printed panel shows the connections, which helps in setting up the circuit correctly, and the built-in battery and galvanometer keys keep the wiring on the bench to a minimum.
Frequently Asked Questions
What are the ratio arm values of this Post Office Box?
It has three pairs of ratio arms, each of 10, 100 and 1000 Ω, alongside a resistance arm of 16 coils from 1 to 5000 Ω with an infinity plug.
What keys are built in?
Two spring keys with special contacts are fitted, one for the battery and one for the galvanometer.
Related: Physics Lab Equipment, Resistance Box Plug Type (Constantan / Manganin Coil), Galvanometer, Plug Key.
For a quotation on the Post Office Box-Plug Type (Constantan & Manganin Coil), contact School Educational Instrument.
