Resistance Box Constantan & Manganin Manufacturer,Supplier and Exporter in India
Product Code : EL-SI-8096
Jlab Export is a leading Resistance Box Constantan & Manganin Manufacturer,and suppliers in India
Resistance Box Constantan & Manganin (code EL-SI-8096) is a decade resistance box for setting precise resistances in physics and electrical measurement labs, offered as Grade A with manganin coils (accuracy ±0.02% to ±0.05%) or Grade B with constantan coils (±0.05% to ±0.1%). Eleven-position switches with phosphor-bronze moving contacts are mounted on a Bakelite panel in a polished teak wood box. It is made by Jain Laboratory Instruments Pvt Ltd (JLab) at its works in Ambala, India.
Specifications
| Parameter | Detail |
|---|---|
| Type | Decade resistance box |
| Switches | Eleven-position switches, designed for low contact resistance |
| Moving contacts | Phosphor-bronze laminations, for long life and repeatable results |
| Contact resistance | Of the order of 0.0015 ohm per decade |
| Panel and case | Insulating Bakelite panel in a polished teak wood box |
| Coil winding | Non-inductively wound, varnished and aged for stable values over a long period |
| Coil wire | Imported double-silk-covered wire: manganin in Grade A boxes, constantan in Grade B boxes |
| Accuracy, Grade A (manganin) | ±0.02% to ±0.05% |
| Accuracy, Grade B (constantan) | ±0.05% to ±0.1% |
| Manganin | Listed as having a negligible temperature coefficient against copper |
| Quality check | Each resistance box is visually inspected before dispatch |
| Pack quantity | Each (sold individually) |
| Minimum order quantity | 10 units |
| Dispatch time | Usually 7–10 working days |
| Product code | EL-SI-8096 |
| Manufacturer | Jain Laboratory Instruments Pvt Ltd (JLab) — OEM |
| Country of origin | India (made in Ambala, Haryana) |
Grade A or Grade B: Which Should You Choose?
| Grade | Coil wire | Accuracy | Suited to |
|---|---|---|---|
| Grade A | Manganin | ±0.02% to ±0.05% | Reference resistances in bridge and potentiometer work where the smallest error matters |
| Grade B | Constantan | ±0.05% to ±0.1% | General teaching experiments with resistance boxes |
Both grades share the eleven-position switches, phosphor-bronze contacts, Bakelite panel and teak wood box. Manganin is the usual wire for reference resistors because its resistance changes very little with temperature and it produces only a small thermoelectric emf against copper terminals. Constantan also holds its resistance well as temperature changes, but its thermo-emf against copper is much larger — the reason copper and constantan are paired in thermocouples — so manganin is preferred for sensitive DC null measurements.
What Is the Resistance Box Used For?
A decade resistance box puts a known, adjustable resistance into a circuit without rewiring. In class 12 physics practicals and college labs it supplies the known arm of a meter bridge or Wheatstone bridge, the series resistance when a galvanometer is converted into a voltmeter, the shunt when it is converted into an ammeter, the resistances for finding a galvanometer’s resistance by the half-deflection method, and the known resistances in potentiometer and Ohm’s law experiments. Grade A boxes also serve as working standards when meters and potentiometers are checked in electrical measurement labs, and the non-inductive winding keeps the coils’ inductance low when a box is used in an AC bridge arm.
Set the dials from the highest decade downwards and turn each switch fully into its position so the phosphor-bronze contacts seat properly. The maximum current is not stated in the listing, so keep currents small, switch off before changing large steps and ask JLab for the rating if your circuit draws more than a bridge or potentiometer current. Keep the panel clean and dry, and store the box closed in its teak case.
What to Specify When Ordering
- Grade — Grade A (manganin, ±0.02% to ±0.05%) or Grade B (constantan, ±0.05% to ±0.1%).
- Number of decades and range — the listing does not state them, so give the total resistance and smallest step you need.
- Quantity — the minimum order is 10 units.
- Companion items — P.O. boxes, bridges, potentiometers or galvanometers for the same practicals can go in one enquiry.
Frequently Asked Questions
What is the difference between Grade A and Grade B?
The coil wire and the accuracy. Grade A boxes use manganin wire and are accurate to ±0.02% to ±0.05%; Grade B boxes use constantan wire and are accurate to ±0.05% to ±0.1%. The switches, contacts, panel and case are the same.
What resistance range does the box cover?
The listing does not give the number of decades or the step values. Tell JLab the range and smallest step your experiments need and ask for the decade arrangement of the box you are quoted.
How low is the contact resistance?
Of the order of 0.0015 ohm per decade, as listed. The moving contacts are phosphor-bronze laminations, chosen for long life and repeatable readings.
Why are the coils non-inductively wound?
Non-inductive winding cancels most of the coil’s inductance, so the box behaves as a pure resistance when it is used with alternating current, for example in an AC bridge arm. The coils are also varnished and aged so their values stay stable over a long period.
Which experiments use a resistance box?
Meter bridge and Wheatstone bridge measurements, conversion of a galvanometer into an ammeter or voltmeter, the half-deflection method for galvanometer resistance, potentiometer experiments and Ohm’s law, in school and college physics labs.
What does JLab need for an export quotation?
The grade, quantity, destination country and port or city, preferred delivery terms such as FOB or CIF, any packing or labelling requirements and the tender reference if you are buying against a tender.
Who manufactures this resistance box?
Jain Laboratory Instruments Pvt Ltd (JLab) makes it at its works in Ambala, Haryana, India, and quotes for it directly.
OEM Manufacturer
JLab is the trading name of Jain Laboratory Instruments Pvt Ltd, a manufacturer of physics and electrical lab instruments in India, incorporated in 2017 and based on Hargolal Road, Ambala, Haryana. Its resistance boxes are made at JLab’s own works, not bought in from a trader, so schools, colleges, dealers and importers deal directly with the maker, every box is visually inspected before it leaves, and repeat orders are handled by the manufacturer. The company is registered for GST under GSTIN 06AADCJ9848D1ZE and holds Legal Entity Identifier 549300DTGS77DGYD6N03. JLab exports worldwide and ships to buyers in every region — Jordan in the Middle East, Belgium in Western Europe, Japan in East Asia, Poland in Eastern Europe and Ivory Coast in West Africa, for instance. Tender buyers can refer to the JLab lab tenders page.
Related Resistance and Bridge Equipment
- Resistance Substitution Box — standard preferred-value resistors selected by a rotary switch.
- Resistance P.O. Box — a plug-type P.O. box with constantan coils and brass blocks.
- P.O. Box Ratio Manganin Coil — P.O. box ratio arms wound with manganin.
- Portable Wheatstone Bridge — a self-contained bridge with four decade dials and a built-in galvanometer.
- Potentiometer with Pencil Jockey — a four-wire constantan potentiometer for emf and resistance work.
- Calibration of Voltmeter & Ammeter — a unit for standardising a potentiometer and calibrating meters.
See the full Scientific Instrument range and the Indian Instruments section.
Request a Quote
Quotes come direct from the manufacturer. Use the Add To Cart enquiry button on this page, or send the grade, the range you need, the quantity (minimum 10 units) and your delivery location through the contact page.
Last updated: 8 October 2026
