"Vaiseshika" Precision DC Potentiometer
Type : 9408

Description The Precision DC Potentiometer Type - 9408 has been designed to provide the highest standards of accuracy over a period of many years without any maintenance, whilst at the same time allowing rapid and easy operation. The most outstanding contribution to the development of potential meters in recent years resulted from the introduction of the unique Vaiseshika Low Resistance Precision instrument switch, used through out the Precision DC Potentiometer. This switch was developed after several years of research into the fundamental factors affecting contact resistance. The stationary contacts are silver clad copper bars, mounted in a robust insulating frame. The brush, which is composed of several contact springs, each of which is independent of the others and is unrestricted in its movement, makes a bridge contact between adjacent bars in a symmetrical manner. As a result, low and consistent contact resistance is achieved without high contact pressure or mechanical wear. After a life test of some 20,000 operations, the switch was still mechanically sound and its stability had actually improved in the narrow range specified. The over all switch resistance is approximately 0.001 Ohm and the variation of contact resistance is less than ± 0.0001 hm.

Features

Accurate measurement of potential, current and resistance.

Highest quality manganin wire well-aged standards.

High stepwise resolution of 2microvolt at the last range switch setting.

Excellent Accuracy of ± 0.02% to +/- 0.05%.

Impeccable craftsmanship in construction, rigorous testing and simplicity of operation

Hard silver plated, self-cleaning switches with minimum contact resistance errors

Controls

A calibrated dial having graduation from 0 to 1.7 volt with a resolution of 0.1 volt is utilized for measurements. A slidewire system has been incorporated in the bridge having calibrations in millivolt with each millivolt subdivided in five parts. Thus the slidewire gives a least count of 0.0002 volt. Coarse and fine potentiometers provide added versatility in measurements and current control. Battery, standard cell and galvanometer can be connected to three pairs of terminals and choice of selection can be made through a three way rotary switch.

Specification

Range of Measurement: 0 to 1.8 volt.

Range 1st switch in steps of Slide Wire Smallest Reading X1 : 0 to 1.7V : 0.1 V : 0 to 0.1V : 0.0002 V X0.1 : 0 to 0.17V : 0.01 V : 0 to0.01V : 0.00002 V

Range   Range Switch Setting 0 to 1.8 volt :  x1 0 to 0.18 volt :  x 0.1     Smallest reading with multiplier of 0.1 : 0.00002 Volt Resistance : 11 ohm per Volt Accuracy of measurement : 100mV to 1.8V :  upto 99 mV +/- 0.02% +/- 0.05% or +/- 1 slide  wire division which ever is greater on all  the two ranges Dimensions ; 550(L) x 300(B) x 220(H) approx. Weight (in Kg.) : 7 (approx.)

Accessories for Precision DC / Vernier Potentiometer:

Spot Reflecting Galvanometer Type 9407A (Essential Assessory) The Spot Reflecting Galvanometer will serve as a null detector to obtain the balance point in the circuit. The instrument is housed in a black bakelite case with lamp and scale arrangement for providing moving spot on the calibrated scale. The galvanometer resistance is of the order of125 ohms. The critical damping resistance will be1000 ohms and the galvanometer will be working on 220 volt AC
VOLT RATIO BOX TYPE 9407B (Essential Accessory) The Volt Ratio Box is required if the voltage to be measured is above 2 volts. The Volt Ratio Box consists of a high resistance of the order of 37.5 K ohms having a number of tappings, the resistance between the various pair of tappings being carefully adjusted . Range for voltage 1.5, 15, 30, 150 and 750 Volts. Resistance 37.5 K Accuracy ± 0.05% The Volt Ratio Box employs high stability and low temperature co-efficient manganin coils which gives remarkably stable readings over varied range of voltages. The coils are having long ageing and have been subjected to vacuum impregnation to avoid any damage to the measuring accuracy due to moisture, corrosion or salt conditions prevailing in the measuring area.
ELECTRONIC 2 VOLT ACCUMULATOR (DC SOURCE) TYPE 9407C (Essential Accessory) This accumulator delivers 2 Volt, 500 mA stabilized DC regulated power supply. The electronic unit is having low ripple content and employs solid state circuitry using LSI/MSI circuits and TTL components. Two terminals are given at the front panel to deliver the constant voltage. The unit is used to energize potentiometers during working.
STANDARD CELL DC TYPE 9407 D (Essential Accessory) The Standard Cell is used in the Potentiometers to calibrate a potentiometer against a standard and stable DC volt signal varying from 1.0185 to depending upon the ambient temperature with variation of 40mV/°C. Suitable compensations are provided in each Potentiometer to take account of the variation in the value of the DC voltage obtainable from the Standard Cell. One Standard Cell is required with one Potentiometer. It is essentially a calibration reference standard for the Potentiometer and thus a part and parcel of the support accessories system of the Potentiometer.
DECADE RESISTANCE BOX TYPE 7400 (Optional Accessory) The Standard Decade Resistance Box Type 7400 is used to calibrate current and volt meters with the help of Potentiometer. The range of the Resistance Box is from 0.01 ohm to 100 K having decade steps from 0.01 ohm to 10 K ohm. The Box employs manganin coil to provide high stability to the resistance values having accuracy of 0.05%.