Toshniwal Industries Private Limited

Decade Resistance Box consists of decade switches with resistors. Each decade switch has 1-10 positions in addition to zero position. Specially designed switch with self cleaning and silver plated contacts ensure very low contact resistance and long life.
Resistances of 10 k ohms & lower are made of non-inductively wound selected manganin. Coils are heat treated and aged for long term stability.
100k and 1M ohm decades have selected & precision metal film resistors of very low temperature co-efficient. All the decades are housed in metallic/wooden rugged casing and are provided with knobs having ribs for comfortable operation. Decade Resistance Boxes are available with 4, 6, 7 & 8 decades and offer a wide choice of resistances to meet with almost every requirement in industry & laboratories.

This instrument employs the double Kelvin Bridge principle for accurate measurement of low resistances. Twin, 5-position ratio arm, combined with a decade & slide wire, provide a wide range of resistance measurement, i.e. 0.2 micro-ohms to 11 ohms with high accuracy. Two or four terminal measurements may be employed. Current up to 10 A can be used during measurement.
All controls are simple to operate. Thermal e.m.f. may be taken into account using the three position (Normal/Off/Reverse) current switch. Both ratio arms are operated by one switch. The press keys give full and reduced sensitivity control for the galvanometer detector. Readings are obtained direct from decade and slide wire scale multiplied by ratio arm switch setting. All dials, keys & terminals are positioned on a instrument panel mounted in polished wooden case with hinged lid.For measurement of resistance of thicker wires, strips and rods up to 15 mm dia, Conductor Clamps are also available. These Conductor Clamps have terminals for current as well as potential connections and are available for lengths of 100 cm and 50 cm. Conductor Clamp, PL39.01-suitable for wire/ rod length 100 cm. Conductor Clamp, PL39.02-suitable for wire/ rod length 50 cm. For convenience of operation, a mains operated 10 A DC power supply Cat no.:PL39PS, power: 230V AC, 50 Hz is also available.

The instrument consists of a taut suspension movement, light source, projection system, scale and sensitivity control switch. All components of the instrument are housed in a dust free aluminium cabinet nicely finished by stoving enamel paint.
The light source consisting of a 4V 4W lamp is mounted on a small rectangular detachable plate fixed in front of the galvanometer housing to allow the bulb to be replaced. A circular plate is fixed on this rectangular plate which enables the exact adjustment of light spot. 4V supply for the lamp can be obtained through 220-240V AC mains. The Galvanometer indicator consists of a bright circular spot of light with a vertical hair line shadow on a translucent scale with dual graduations in millimeters (0….14 & 7….0….7 cms).
The most attractive feature of the instrument is a built-in Universal Shunt, which adjusts the galvanometer sensitivity in convenient steps by means of a switch. The shunt not only maintains the critical damped conditions in all settings, but also provides a constant terminal resistance, so essential in measurements where galvanometer serves as a detector.
There are five sensitivity positions: DIRECT, 1, 0.05, 0.01 and 0.001 for the galvanometer and a ‘SHORTED’ position for the safety of the galvanometer movement during transportation.
Two models are available for different purposes:

• Voltage sensitive model Cat. No. PL64- In this model the coil resistance is low and it is useful for measurement of low resistances.
• Current sensitive model Cat No PL64.01- In this model the coil resistance is high and it is useful where high resistances are measured.

Features:

• High sensitivity (70 mm / µA)
• Five sensitivity positions
• Built-in universal shunt
• Constant terminal resistance 

Specifications

Cat No.	Resistance Of Coil in ohms	Period in Seconds	Critical damping resistance in Ohms	Terminal resistance in Ohms	Sensitivity
PL64	20	2	140	17.5	7	0.35
PL64.01	1500	1.7	13000	1345	70	0.046

Over all size : 280 x 185 x 140 mm
Weight : 3 Kg

TOSHNIWAL Portable Wheatstone Bridge PL32.03 is a very precise and portable instrument. This Wheatstone Bridge is designed to afford maximum convenience for a wide range of resistance measurement without the need of external accessories. The resistance coils in ratio & series arms are made from non-inductively wound and aged best quality manganin wires having negligible effect of ambient temperature variation, for long term stability. Switches used in this instrument are of self cleaning type having very low contact resistance & long life. Taut band suspended galvanometer is provided for null detection. Built-in dry cell batteries can be easily replaced. Battery ON/OFF & test keys are provided on the instrument panel.
Features:

• Measures resistance from 1 milliohm to 11.11 mega ohms.
• Use of series arm as Decade Resistance Box.
• Lead resistance compensation provision for measuring low value resistances.
• Higher sensitivity by using external galvanometer.
• Use of additional power supply possible.
• Detection of cable fault by Varley Loop Test method.
• Batteries easily replaceable.
• Separate use of built-in Galvanometer.

Specifications:

Measurement Capability	1milliohm---11.11 megaohms
Measurement Ranges	1 milliohm---11.11 ohms 10 milliohms---111.1 ohms 100 milliohms---1.111 k ohms 1 ohm---11.11 k ohms 10 ohms---111.1 k ohms 100 ohms---1.111 megaohms 1 k ohms---11.11 megaohms
Measurement Accuracy	± 0.075 %
Series Arm	10 (1000 +100+10+1) ohms
Accuracy of Series Arm	± 0.05 %
Null Detector Galvanometer	Ri 20 ohms,1mm/µA sensitivity
Battery	3 cells of 1.5 V, R 14 size
Size	370x260x155 mm approx.
Weight	6.4 kgs (approx)

Applications:
Used in cable manufacturing industries, Telecommunication Equipment Industries, Chemical, Petro-complex and refineries, Instrumentation, Electronic equipment centres, etc.

he potentiometer consists of a slide wire and switch with precision coils. Both slide wire and coils are made from manganin wire and are aged for long term stability before mounting in instrument. The measuring range of the potentiometer can be selected by a range selector switch. Electronic Voltage Reference (EVR) having performance comparable to standard cell operates on built-in dry cells. By adjusting the standardization pots, the measuring potentiometer can be standardized against built-in EVR. A taut suspended galvanometer with the provision of zero adjustment acts as null indicator. Batteries for EVR and for potentiometer are housed in a small pocket in the wooden casing of instrument and are easily accessible for replacement without disturbing the precision parts of this instrument.
This instrument is provided with keys for battery on/off, standardization test and for checking the voltage of battery supplying power to EVR. A plug socket and a jack for use with external galvanometer, for increasing sensitivity of measurement is also provided. The entire assembly is mounted on a Perspex panel and housed in wooden case with a carrying strap. The lid of the wooden case carries operating instructions, circuit diagram and when the lid is closed, the power supply from the built-in battery is automatically cut off.
Features:

• Used for measuring DC potential difference or voltages.
• Equipped with electronic voltage reference, standardization circuit, potentiometer, galvanometer & power supply and yet light weight and portable.
• Useful in most industrial & laboratory applications, where accuracy is of prime importance.

Specifications:

Measurement range selector	Main dial (with 18 steps)	Slide wire (cont. adjustable)	Range	Resolution
x 1	0-1.7 V	100 mV	0-1.8 V	1 mV
x 0.1	0-170 mV	10 mV	0-180 mV	100 µV
x 0.01	0-17 mV	1 mV	0-18 mV	10 µV

Internal Resistance	250 ohms per volt
Measuring accuracy	± 0.1% of range or ± 1 division of slide wire, whichever is greater.
Standard source	Electronic Voltage Reference
Standardization	By coarse and fine control pots
Galvanometer	Built-in taut suspended, pointer type
Sensitivity	1 mm / µA OR 0.05 mm / µV
DC voltage source	0-1.8 V adjustable
Keys	For battery ON/OFF, standardization, test and EVR Test
Power Supply	Two dry cells of 1.5 V R20 size for Potentiometer Two dry cells of 1.5 V R20 size for EVR
External Galvanometer	Low Resistance, higher sensitivity can be used e.g. Type PL64
Size	285 x 215 x 164 mm (approx.)
Weight	5.0 kgs (approx.)

Rheostats are mainly used for regulating electric current in industry and laboratory where these are used as adjustable resistors in electrical circuits. With three terminal provisions, these can be used to vary a d c potential smoothly from zero to maximum.
toshniwal rheostats consist of resistance wire wound on a former which is made from solid drawn hexagonal steel tube vitreous enameled, ensuring good mechanical strength and sturdiness. The tube is fitted in two end castings insulated with micanite cups. the brush gear slides on a highly polished square slide rod. The brush is of copper graphite with pigtail connections. Two heat resisting compression spring hold brush family in contact with the resistance wires. Copper graphite brush provides necessary lubrication to prevent wear and tear of wire even at elevated temperatures. the brush is housed in a slider knob of moulded bakelite designed for easy handling. different designs in a single tube and double tube models are available to meet with demands of different applications. in many applications larger values of resistance are required to be accommodated in small space but at the same time the current rating desired varies for lower to the higher values of resistance. For such requirements rheostats are also available in space saving graded winding designs. For requirement of graded rheostats desired resistance, voltage, maximum and reduced current rating should be stated. lead screw type rheostats are also available for precision and smooth setting of brush position using hand wheel provided axially or at right angles to the lead screw which replaces the slide shaft in this design.

features:

• industrial quality components.
• trouble-free long service.
• wide range of resistance values and current – carrying capacities.