Educational Instruments

Product Details:

 

• Measures current down to 1pA

• All solid state and IC design

• Very low offset current

This is a very versatile multipurpose equipment for the measurement of low dc currents. It has 6 decade ranges with 100% over-ranging from 10-9A to 10-4A. For the ease, readings are directly obtained on a 3½ digit DPM. The instrument uses a well designed precision FET input electrometer operational amplifier AD549, which offers the lowest input bias currents (50fA with ±5V supplies) available in any standard operational amplifier. The excellent characteristics of AD549, ultra low bias current, low offset voltage, low drift and low noise have been fully utilized to obtain best results in the present picoammeter. The first operational amplifier AD549 is used in low level current to voltage configuration and the output has been directly read on a 3½ digit panel meter. The instrument is capable of accepting either polarity of the input current. Well regulated power supplies are incorporated to use the instrument upto 10% changes in a.c. main’s voltage.

Applications

Current from Photomultiplier tubes,

Photometers etc.

Leakage currents in solid state

devices.

FET gate and tube grid-voltage

without loading errors

Current through very high resistance’s

in conjunction with a power

supply

Potentials across semiconductors,

piezoelectric system & pH/plon

sensitive electrodes

Electrical conductivity of air

Very low current oxygen sensors

Specifications

Multiplier X1, X10, X102, X103, X104, X105

Accuracy 0.2% for all ranges

Resolution 1pA, 10pA, 100pA, 1nA, 10nA, 100nA

Input Resistance 2.5KW, 0.25KW, 25W, 2.5W, 0.25W, 0.025W

Display 3½ digit 7 segment LED (12.5mm height) with auto polarity

Input Through amphenol connector

Power Supply 220V ±10%, 50Hz

Weight 2.5Kg

Dimensions 240mm X 275mm X 120mm

 

Request
Callback

Product Details:

·         Measures current down to 100pA

·         All solid state and IC design

·         Accepts either polarity of input current

Digital Nanoammeter, DNM-121, a rugged and low cost instrument, is a product of extensive R&D using high input impedance integrated circuits. It has 4 decade ranges with 100% overranging. The unit is suitable for current measurement in the range of 100pA to 200μA. For the ease, readings are directly obtained on a 3½ digit DPM. The instrument is capable of accepting either polarity of the input current. The very low leakage current of the input stage combined with the high linearity fast response due to high negative feedback enables accurate and easily reproducible measurements. The instrument uses a FET input operational amplifier that offers the very low input bias current, low offset voltage, low drift and noise. These characteristics have been fully utilized in the present Nanoammeter. This operational amplifier is used in low level current to voltage configuration.

Applications

·         To measure current from photomultiplier tubes, photometer etc.

·         Leakage currents in solid state devices. FET gate and tube grid voltages without loading errors.

·         Current through very high resistance in conjunction with a power supply.

·         Potentials across semiconductors, piezoelectric systems & pH electrodes.

Specifications

Range 100nA, 1μA, 10μA, 100μA with 100% over-ranging

Accuracy 0.2% for all ranges

Resolution 0.1nA

Input Resistance 25W, 2.5W, 0.25W, 0.025W

Display 3½ digit 7 segment LED (12.5mm height) with auto polarity and decimal indication

Input Through amphenol connector

Power Supply 220V±10%, 50Hz

Weight 2.5Kg

Dimensions 240mm X 275mm X 120mm

Request
Callback

Product Details:

Digital Microvoltmeter

Very low temperature drift

Low dc input bias current-10pA

Measures voltage down to 1μV

Automatic polarity indication

Built-in polarity indication

Recorder facility (optional)

Introduction

Digital Microvoltmeter, DMV-001 is a very

versatile multipurpose instrument for the

measurement of low dc voltage. It has 5 decade

ranges from 1mV to 10V with 100% overranging.

For better accuracy and convenience,

readings are directly obtained on 3½ digit DPM

(Digital Panel Meter). This instrument uses a

very well designed chopper stabilized IC

ampli er. This ampli er offers exceptionally low

offset voltage and input bias parameters,

combined with excellent speed characteristics.

Filter circuit is provided to reduce the line

pickups of 50Hz. All internal power supplies are

IC regulated.

Applications

·        DC voltage measurements from high impedance sources; output of

photomultiplier tubes, photo cells, radiation detector etc.

·        Very low voltage measurement, direct measurement of

thermocouple output to read temperatures with a resolution of

1/40th of a degree (Chromel-Alumel).

·        General purpose laboratory instrument for voltages upto

19.99VDC. (Hall Effect, Four Probe, Thermoluminescence, Transistor and Diode characteristics etc.).

Specification

Range : 1mV, 10mV, 100mV, 1V & 10V with 100%

over-ranging.

Resolution : 1μV

Accuracy : ±0.2% ±1 digit

Stability : Within ±1 digit

Input Impedance : >1000MW (10MW on 10V range)

Display : 3½ digit, 7 segment LED with autopolarity and

decimal indication

Interfacing : USB (in DMV-001-C2 only)

Software : DACC and CAMM, both Window compatible

Power Supply : 220V ±10%, 50Hz

Weight : 2.5Kg

Dimensions : 245mm X 280mm X 120mm

Request
Callback

Product Details:

Frank Hertz Experiment

Introduction

From the early spectroscopic work it is clear that atoms emitted radiation at discrete frequencies; from Bohr’s model, the frequency of the radiation v is related to the change of energy levels through DE=hn. It is then to be expected that transfer of energy to atomic electrons by any mechanism should always be in discrete amounts. One such mechanism of energy transfer is through inelastic scattering of low-energy electrons.

Frank and Hertz in 1914 set out to verify these

considerations.

(i) lt is possible to excite atoms by low energy electron bombardment.

(ii) The energy transferred from electrons to the atoms always had discrete values.

(iii) The values so obtained for the energy levels were in agreement with spectroscopic results.

Thus the existence of atomic energy levels put forward by Bohr can be proved directly. It is a very important experiment and can be performed in any college or University level laboratory.

Operating Principle

The Frank-Hertz tube in this instrument is a tetrode filled with the v a p o u r o f t h e

experimental substance. Fig.1 indicates the basic scheme of experiment. The electrons emitted by fi l a m e n t c a n b e a c c e l e ra t e d b y t h e potential V between G2K

the cathode and the grid G . The grid G, helps 2 in minimising space charge effects. The grids are wire mesh and allow the electrons to pass through. The plate A is maintained at a potential slightly negative with respect to the grid G . This helps in making the dips in the plate current 2 more prominent. ln this experiment, the electron current is measured as a function of the voltage V . As the voltage increases, the electron G2K

energy goes up and so the electron can overcome the retarding potential V to reach the plate A. This gives rise to a current in the G2A ammeter, which initially increases. As the voltage further increases, the electron energy reaches the threshold value to excite the atom in its first allowed excited state. In doing so, the electrons loose energy and therefore the number of electrons reaching the plate decreases. This decrease is proportional to the number of inelastic collisions that have occured. When the V G2K is

increased further and reaches a value twice that of the first excitation potential, it is possible for an electron to excite an atom halfway between the grids, loose all its energy, and then gain anew enough energy to excite a second dip in the current. The advantage of this type of configuration of the potential is that the current dips are much more pronounced, and it is easy to obtain five fold or even larger multiplicity in the excitation of the first level.Frank-Hertz Experiment Set-up, Model: FH-3001,

consists of the following:

Argon filled tetrode

Filament Power Supply : 2.6~3.4V continuously

variable

Grids Power Supplies

V : 1.3-5 V continuously variable G1K

V : 1.3 - 12V continuously variable G2K

V : 0 - 95V continuously variable G2K

All the power supplies are highly stabilised and output

voltages can be read on 3 V2 digit, 7 segment LED DPM

with autopolarity and decimal indication through a

selector switch.

Saw tooth waveform for CRO display

Scanning Voltage : 0-80V

Scanning Frequency : 115±20Hz

Multirange Digital Ammeter

Display : 3½ digit 7 segment LED

Range Multiplier: 10-7 , 10-8 & 10-9

Request
Callback

Product Details:

PLANCK’S CONSTANT EXPERIMENT

1. Determination of Planck’s Constant and Work Function of Materials by Photoelectric

Effect

It was observed as early as 1905 that most metals under influence of radiation, emit electrons. This

phenomnon was termed as photoelectric emission. The detailed study of it has shown.

1. That the emission process depends strongly on frequency of radiation.

2. For each metal there exists a critical frequency such that light of lower frequency is unable to liberate

electrons, while light of higher frequency always does.

3. The emission of electron occurs within a very short time interval after arrival of the radiation and

member of electrons is strictly proportional to the intensity of this radiation.

The experimental facts given above are among the strongest evidence that the electromagnetic field is

quantified and the field consists of quanta of energy E= hn where n is the frequency of the radiation and h is

the Planck’s constant. These quanta are called photons.

Further it is assumed that electrons are bound inside the metal surface with an energy ef, where f is called

work function. It then follows that if the frequency of the light is such that

hn > ef

it will be possible to eject photoelectron, while if hn

excess energy of quantum appears as kinetic energy of the electron, so that

hn = 2

1 mv2 + ef

which is the famous photoelectrons equation formulated by Einstein in 1905.

The energy of emitted photoelectrons can be measured by simple retarding potential techniques as is done

in this experiment. When a retarding potential V0 is used to measure kinetic energy of electrons Ee, we

have,

Ee =2/1 mv2 = eV0 or V0 = eh

n - f

So when we plot a graph V0 as a function of n, the slope of the straight line yields h and the intercept of

extrapolated point n=0 can give work function f.

2. To verify inverse square law of radiation using a photoelectric cell

If L is the luminous intensity of an electric lamp and E is the illuminanscence (intensity of illumination) at

point r form it, then according to inverse square law.

E = L/2 r

If this light is allowed to fall on the cathode of a photo-electric cell, then the photo-electric current (I) would

be proportional to E.

E = L/2 r=K.I

Hence a graph between

r 2 1

and I is a straight line, which verify the inverse square law of radiation.

THE APPARATUS CONSIST OF THE FOLLOWING :

1. Photo Sensitive Device : Vacuum photo tube.

2. Light source : Halogen tungsten lamp 12V/35W.

3. Colour Filters : 635nm, 570nm, 540nm, 500nm & 460nm.

4. Accelerating Voltage : Regulated Voltage Power Supply

Output : ± 15 V continuously variable through multi-turn pot

Display : 3 ½ digit 7-segment LED

Accuracy : ±0.2%

5. Current Detecting Unit : Digital Nanoammeter

It is high stability low current measuring instrument

Range : 1000 μA, 100 μA, 10 μA & 1μA with 100 % over ranging facility

Resolution : 1nA at 1 μA range

Display : 3 ½ digit 7-segment LED

Accuracy : ±0.2%

6. Power Requirement : 220V ± 10%, 50Hz.

7. Optical Bench : The light source can be moved along it to adjust the distance between light source and

phototube. Scale length is 400 mm. A drawtube is provided to install colour filters, a focus lense is fixed

in the back end.

Request
Callback

Product Details:

Introduction

This experiment aims at measuring the charge of an electron and is perhaps the most basic of allatomic physics or modern physics laboratory experiments. It won Millikan the Nobal Prize in the year 1923.

The experiment depends on the ability to control, measure and balance very small force of the order 10-14N. The set-up consists of two horizontal parallel plates separated by about 5mm. The upper plate has a small hole through which microscopic oil droplets are sprayed in between the two plates with the help of an atomizer which is like a common perfume sprayer. These droplets get charged due to the frictional force during spraying. The free fall of these droplets in the space between the

plates is observed in the gravitational field. A measurement of the velocity of fall along with the use of Stokes law leads to the calculation of the mass of the droplets and their radii if the oil density is known. These are of the order of 10-15kg and 10-6m respectively. By applying a potential difference between the plates, a uniform electric field is produced in the space between the plates. A measurement of the velocity of the negatively charged droplets rising in the electric field allows a calculation of the electric force on the droplets and hence the charge carried by them. In the

experiment the droplets which rise and fall slowly are selected as they are expected to have a fairly small charge. These droplets are made to rise and fall several times. The repetitions of measurement of the velocities of rise and fall reduce the random error of their means. A fairly large number of

droplets are observed and their charges are calculated. The analysis of the data on the total charge carried by the droplets shows that these total charges are integral multiples of a certain smallest charge which is the charge of an electron. This result also

shows that the charge is quantized.

The measurement of the charge on the electron can lead to the calculation of Avogadro’s number. The charge F (the Faraday) required to electro-deposit one gram equivalent of an element on an electrode during electrolysis is equal to the charge of the electron multiplied by the number of molecules in a mole. The Faraday has been found to be F = 9.625×10 7 coulombs per kilogram equivalent weight. Hence Avogadro’s number N = F/e.

Request
Callback

Product Details:

Zeeman Effect Experiment

Description of the Experimental Set-up

Experimentental Set-up for Zeeman

Experiment

The set-up consists of the following:

1. High Resolution Fabry Perot Etalon, FP-01

2. Mercury Discharge Tube, MT-01 (Low Pressure Mercury Discharge Tube)

3. Power Supply for MT-01, ZPS-02 (High Voltage Power Supply for Discharge Tube)

4. Narrow Band Interference Filter, IF-01

·        Central Wave Length: 546nm

·        Tmax: 74%

·        HBW: 8nm

5. Polarizer with lens, PL-01

6. Optical Bench: OB-01

7. CCD Camera: CAM-700 (High Resolution CCD Camera)

8. Telescope with Focussing Lens: FL-01

9. Monitor 17”: TV-17

10. Electromagnet, EMU-50T (Specifications as per datasheet)

11. Constant Current Power Supply, DPS-50 (Specifications as per datasheet)

12. Digital Gaussmeter, DGM-

102 (Specifications as per datasheet) The experimental set-up is complete in all respect.

Result

The interference pattern is in

the form of circular rings. These

are split when the magnetic

field is switched on. The amount

of splitting depends on the

external magnetic field, charge

to mass ratio of electron and

L a n d e ‘s g - f a c t o rs o f t h e

e l e c t r o n i c e n e r g y l e v e l s

involved in the transition. These

Request
Callback

Product Details:

Introduction

Regular arrangement of atoms in molecules and extended solids is very common. In crystalline solids the atoms are arranged in repeating three-dimensional arrays or lattices. Information regarding atomic bond distances and angles is fundamental to understanding the chemical and physical properties of materials. Since atomic dimensions are of the order of angstroms (10 m), unraveling the relative atomic positions of a solid requires a physical technique that operates on a similar spatial scale, Diffraction experiments involving X-ray, electron and neutron sources have therefore played a very crucial role in unraveling these structures. The significance of these experiments in science and engineering courses has been recognized. However, the cost of the equipment and the hazards associated with these experiments have made them very difficult to be

integrated and included in a teaching laboratory setting. The present set-up overcomes these limitations. An increase in scale by thousands from short wavelengths of X-rays to the long wavelengths of visible light, and by hundreds of thousands from an array of atoms in a crystal or an extended solid to an array of dots, allows us to replicate the basic features of a structural determination experiment in a teaching laboratory.

In place of Bragg diffraction whose results are to be simulated, we use Fraunhofer diffraction. Visible laser light passes through an array of scattering centers (dots) on a 35 mm slide. The diffraction pattern is viewed at

what is effectively infinite distance (a meter or so). This arrangement is capable of illustrating many of the essential features of the standard X-ray experiment. Mathematically, the equations for Fraunhofer and Bragg diffraction have a similar functional dependence on the interatomic distance, wavelength and the scattering angle. The symmetry of the diffraction pattern is same as the symmetry of the lattice causing the diffraction.

The central piece of the set-up is a slide (transparency) with eight (A-H) different arrangements of scattering

centers (dots) on different portions of the slide (Figure 3). The examples presented here serve to illustrate how the spacings, symmetries, spot intensities and systematic absences in a diffraction pattern are related to the lattice from which it is derived. Although these are two-dimensional lattices, they mimic what would be observed for diffraction from particular three-dimensional structures that are viewed in projection perpendicular to a face.

Request
Callback

Product Details:

Probes Arrangement

Three probe arrangements are provided with the setup. For solids, two different size arrangements are given, one for 10mm sample pellets and the other for 50mm sample pellets. Both consist of parallel plates set in insulated medium. Sturdy parallel wire lead is used to minimize external disturbance.

For liquids a separate arrangement is provided consisting of two polished brass cylinders fixed coaxially with insulating gaskets at the two ends. These gaskets have holes, in the lower one for allowing the experimental liquid to flow in between the cylinders, and in the upper one for communication with the atmosphere. This arrangement is mounted vertically and can be moved up and down with a rack-and-pinion set-up. It is put in a vessel containing the experimental liquid. The outer surface of the outer cylinder has a vertical scale to measure the height of the liquid within the cylinders. Proper leads are provided for connection to the Capacitance Meter.

Samples

Glass, Bakelite, Teflon, PZT Sample (Lead Titanate), Carbon Tetrachloride Liquid

Digital Capacitance Meter

This is a compact direct reading microcontroller based high resolution instrument for the measurement of capacitance of the sample.

SPECIFICATIONS

Range :    0pf – 50mf

Resolution    : 0.01pf

Display :    16 x 2 LCD display with back light

Accuracy       : Better than 1%

Zero Setting :    Push button zero setting

Request
Callback

Product Details:

Description of the Experiment Set-up

Probes Arrangement

It has two individually spring loaded probes. The probes arrangement is mounted in a suitable stand of high quality alumina which also holds the sample plate. To ensure the correct measurement of sample temperature, the thermocouple junction is embedded in the sample plate just below the sample. This stand also serves as the lid of temperature controlled oven.

Proper leads are provided for connection to Capacitance Meter and Temperature Controller

Sample

Modified lead titanate (test sample)

Oven

This is a high quality temperature controlled oven. The

heating element used is a high grade Kanthal-D. It is

cover. Further the top portion is also suitably covered

to meet the safety standard. The oven has been

designed for fast heating and cooling rates, which

enhances the effectiveness of the controller.

Main Units

The Set-up consists of two units housed in the same cabinet.

(i) Temperature Controller

It is a high quality PID controller where the temperatures can be

set and controlled easily. P, I and D can be adjusted by the user

and can also be kept on Auto-tuning.

Specification

Temperature Range Ambient to 600° C

Power Supply 100-240VAC; 50/60Hz

Display Method 7 Segment LED display [Processing value (PV)

:Red, Setting value (SV) :Green]

Input Sensor Thermocouple (Chromel - Alumel)

Control Method PID, ON/OFF Control, P, PI, PD, PIDF, PIDS

Display Accuracy ± 0.3%

Setting Type Setting by front push bottons

Proportional Band (P) 0 to 100.0%

Integral Time (I) 0 to 3600 Sec

Derivative Time (D) 0 to 3600 Sec

Sampling Time 0 to 120 Sec

Sampling Time 0.5 Sec

Setting (P, I & D) Manual / Auto

Digital Capacitance Meter

It is a handheld instrument, mounted in a cabinet for convenience, It uses CMOS double level A/D convertor that is automatic in

zeroing and polar selection.

Features

·        LCD Display

·        Data - Hold Switch (HOLD)

·        Cx+, Cx - Input Jack

·        Back Light Button Switch

·        Rotary Switch: Use this switch to select functions and ranges

·        Wide measuring range, covering 9 measuring sections from 0.1pf to 20,000μF that includes nominal value of any capacitance

Power: One 9V battery

Request
Callback

Product Details:

Study of Dielectric Constant and Curie Temperature of Ferroelectric Ceramics

Dielectric or electrical insulating material are understood as the material in which electrostic field can persist for long times. Layers of such substance are commonly inserted into capacitors to improve their perfomance, and the term dielectric refers specifically to this application. An electric field polarizes the molecules of dielectric producing concentrations of charge on its surface that create an electric field opposed (antiparallel) to that of capacitor. This reduces the electric potential. Considered in reverse, this means that, with a dielectric, a given electric potential causes the capacitor to

accumulate a larger charge.

Applications

Beside the common and well known application of capacitors in electrical and electronic circuits, the capacitors with an exposed and porous dielectric can be used to measure humidity in air.

A huge leap in the research on dielectric (ferroelectric materials) came in 1950’s, leading to the wide spread use of Barium Titanate (BaTiO3-Perovskite Structure) based ceramics in capacitor applications and piezoelectric transducer devices. Since then, many other ferroelectric ceramics have been developed and utilized for variety of applications: various type of capacitors, non volatile memories in computers, etc.

Perovskite Structure

Perovskite is family name of a group of materials and the mineral name of calcium titanate (CaTiO3) having a structure of the type ABO3 (Fig 1)

A practical advantage of perovskite structure is that many different cations can be substituted on both A and B sites without changing the over all structure. Even though two cations

are compatible in solution, their behaviour can be radically different when apart from each other. Thus it is possible to manipulate material’s properties such as Curie temperature or

dielectric constant with only a small substitution of given cation

 

All ferroelectric material have a transition called the Curie point (Tc). At T>Tc, the crystal does not exhibit ferroelectricity, while for T

Fig 2 shows the variation of dielectric constant (e) with temperature for Lanthanum doped Lead Zirconate Titanate (PLZT) ceramic, which is cooled from its paraelectric cubic phase to ferroelectric rhombohedral phase.

Request
Callback

Product Details:

The experiment consists of two coils, Constant Current Power Supply and Gaussmeter. The Gaussmeter probe is mounted on a rail with a scale. It can move smoothly and precisely for measurement of magnetic field along the centre of the coils.

The following studies on Biot Savart’s law can be carried out with the set-up:

1. Study of magnetic field due to one coil and calculation of its diameter.

2. Study of Principal of super-imposition of magnetic field due to 2 coils by keeping the distance between the coils at a, >a and

3. Variation of magnetic field with number of turns in the coil.

Legend:

Line 1 - Magnetic Profile when the distance between the coils is >a

Line 2 - Magnetic Profile when the distance between coils is =a

Line 3 - Magnetic Profile when the distance between coils is

Apparatus consists of the following:-

1. Digital Gaussmeter

 

Range: 0-200

Resolution: 0.1G

Accuracy: + 0.5%

Display: 3½ digit 7 segment LED with autopolarity.

2. Two Coil

Diameter: 200mm

Number of turn: 1000

3. Constant Current Power Supply

Current: 0-0.5A Smoothly adjustable

Line Regulato  0.2%for 10% mains variation.

Load Regulator:  0.2 % for 0 to full load

Display: 3½ digit 7 Segment LED Display

Protection: Against overload/ short current.

Request
Callback

Product Details:

 

Introduction

Small ovens are frequently used in class room experiments for the determination o f t e m p e r a t u r e c o e f fi c i e n t s o f resistances, capacitances, zener diodes, and also for studying the leakage currents of semiconductor devices at various temperatures. Conventional arrangement with oven fed from an auto transformer and thermometer type t e m p e r a t u r e m e a s u r e m e n t i s unsatisfactory due to the long time it takes the oven to heat or cool, large time constant of mercury thermometers and difficulty in setting and maintaining a particular temperature.

Description

The unit is a high quality PID controller wherein the temperatures can be set and controlled easily. The P, I and D parameters are factory set for immediate use however the user may adjust these for specific applications as well as auto-tune the oven whenever required. The steps for these are given in the user manual. The controller can be used for both small oven, up to 200°C or a larger oven up to 600°C. The controller uses thermocouple as temperature sensor.

Specifications Of The Oven Controller

The controller is designed around Autonics Temperature Controller Model TZN4S. Although this is a very versatile piece of equipment, below is a summary of the specifications that are relevant to the present application.

Temperature Range : Ambient to 600°C

Power Supply : 00-240VAC; 50/60Hz

Display Method : 7 Segment LED display [Process value

(PV):Red, Set value (SV):Green]

Input Sensor : Thermocouple (Chromel - Alumel)

Control Method : PID, PIDF, PIDS

Display Accuracy : ±0.3%

Setting Type : Setting by front push bottons

Proportional Band (P) : 0 to 100.0%

Integral Time (I) : 0 to 3600 Sec

Derivative Time (D) : 0 to 3600 Sec

Control Time (T) : 1 to 120 Sec

Sampling Time : 0.5 Sec

Setting (P, I & D) : Manual / Auto-tuned

 

Request
Callback

Product Details:

 

Measures True RMS Voltage

Accuracy 1%

High Input Impedance

High Stablility

Excellent Linearity

ACM-102: True RMS A.C. Millivoltmeter, ACM-102 is based on AD536. This is a completely monolithic integrated circuit which performs true rms-to-dc conversion of any waveform. The true rms value of a waveform is more useful quantity than average rectified value, since it relates directly to the power of the signal. The crest factor compensation scheme of the AD536 allows measurement of highly complex signals with wide dynamic range. The crest factor is often overlooked in determining the accuracy of an ac measurement. Crest factor is defined as the ratio of the peak signal amplitude to the rms value of the signal (C.F.=Vp/Vrms). Input signal is appropriately processed through a FET input wide band, extremely fast settling time, low noise amplifier.

ACM-103: In model ACM-103 besides all features of ACM-102, an IC based 1KHz oscillator followed by a buffer, is in-built. This eliminate the need of an external oscillator for purpose, such as determination of h-parameters of a transistor, bridge measurement etc., where spot frequency of 1KHz is most commonly used.

Specifications

Voltage Range 20mV, 200mV, 2V and 20V

Frequency Range 10Hz to 200KHz

Input Impedance 1MW shunted by 25pf on all ranges

Accuracy 1% in the range 10Hz-100KHz; 2% in the range 100KHz-200KHz

Display 3½ digit, 7 segment LED (12.5mm height) with decimal and overflow indication

Power Supply 220V ±10%, 50Hz

Weight 2.5Kg & 3Kg

Accessories 75cm shielded cable with a coaxial connector at one end and banana plugs on

the other end

ACM-103 (Additional Features)

Oscillator Output 0-300mV continuously variable

Frequency 1KHz fixed

 

Request
Callback

Product Details:

 

• Mag. Field Measurement

• Excellent Linearity

• IC Controlled Circuit

• Excellent Stability

DGM-102 operates on the principle of Hall Effect in Semiconductors. A semiconductor carrying current develops and electromotive force, when placed in a magnetic field, in a direction perpendicular to the direction of both electric current and magnetic field. The magnitude of this e.m.f. is proportional to the field intensity, if the current is kept constant. This e.m.f. is called the Hall Voltage. The small Hall Voltage is amplified through a high stability amplifier so that a millivoltmeter connected at the output of the amplifier can be calibrated directly in magnetic field unit (gauss).

Applications

Wide application in industry where accurate measurements of magnetic

field is required. Measurement of steady magnetic field e.g. in loud speakers, dynamos, moving coil instruments etc. Useful in laboratory experiments

involving electromagnets.

Specifications

Range 0-2KG & 0-20KG

Resolution 1G at 0-2KG range

Accuracy ±0.5%

Temperature Upto 50oC

Display 3½ digit, 7 segment LED DPM with auto polarity and over flow indication

Power 220V ±10%, 50Hz

Transducer Hall Probe – InAs

Special Feature Indicate the direction of the magnetic field

Weight 3Kg

Dimensions 280mm X 255mm X 120mm

 

Request
Callback

Product Details:

Four Probe Method

Resistivity of Semiconductor by Four Probe Method at different temperatures

and determination of the Band-gap

The Four Probe Method is one of the standard and most widely used method for the measurement of resistivity of semiconductors. The experimental arrangement is illustrated. In its useful form, the four probes are collinear. The error due to contact resistance, which is specially serious in the electrical measurement on semiconductors, is avoided by the use of two extra contacts (probes) between the current contacts. In this arrangement the contact resistance may all be high compare to the sample

resistance, but as long as the resistance of the sample and contact resistances are small compared with the effective resistance of the voltage measuring device (potentiometer, electrometer or electronic voltmeter), the measured value will remain unaffected. Because of pressure contacts, the arrangement is also specially useful for quick measurement on different samples or sampling different parts of the same sample.

Description of the experimental set-up

1. Probes Arrangement

It has four individually spring loaded probes. The probes are collinear and equally spaced. The

probes are mounted in a teflon bush, which ensure a good electrical insulation between the probes.

A teflon spacer near the tips is also provided to keep the probes at equal distance. The whole – arrangement is mounted on a suitable stand and leads are provided for the voltage measurement.

2. Sample

Germanium crystal in the form of a chip

3. Oven

It is a small oven for the variation of temperature of the crystal from the room temperature to about

200°C (max.)

4. Four Probe Set-up, DFP-02

The set-up consists of three units in the same cabinet.

(i) Multirange Digital Voltmeter

In this unit, intersil 3½ digit single chip A/D Converter ICL 7107 has been used. It has high accuracy like auto zero to less than 10μV, zero drift of less than 1μV/ °C, input bias current of 10pA max. and roll-over error of less than one count. Since the use of internal reference causes the degradation in performance due to internal heating, an external reference has been used.

SPECIFICATIONS

Range X1 (0-200mV) & X10 (0-2V)

Resolution 100μV at X1 range

Accuracy ±0.1% of reading ±1 digit

Impedance 1MW

Display 3½ digit, 7 segment LED (12.5mm height) with auto polarity and decimal indication Overload Indicator Sign of 1 on the left & blanking of other digits

(ii) Constant Current Generator

It is an IC regulated current generator to provide a constant current to the outer probes irrespective of the changing resistance of the sample due to change in temperatures. The basic scheme is to use the feedback principle to limit the load current of the supply to preset maximum value. Variations in the current are achieved by a potentiometer included for that purpose. The supply is a highly regulated and practically ripple free d.c. source. The current is measured by the digital panel meter.

SPECIFICATIONS

Open Circuit Voltage : 18V

Current range : 0-20mA

Resolution : 10μA

Accuracy:

±0.25% of the reading

±1 digit

Load regulation:

0.03% for 0 to full load

Line Regulation:

0.05% for 10% changes

(iii) Oven Power Supply Suitable voltage for the oven is obtained through a step down transformer with a provision for low and high rates of heating. A glowing LED indicates, when the oven power supply is ‘ON’. The experimental set-upis complete in all respect

Typical results obtained from this set-up are shown in the figure.

Request
Callback

Product Details:

Four Probe Set-Up

Resistivity of Semiconductor by Four Probe Method at different

temperatures and determination of the band-gap

The Four Probe Method is one of the standard and most widely used method for the measurement of resistivity. In its useful form, the four probes are collinear. The error due to contact resistance, which is significant in the electrical measurement on semiconductors, is avoided by the use of two extra contacts (probes) between the current contacts. In this arrangement the contact resistance may all be high compare to the sample resistance, but as long as the resistance of the sample and contact resistance's are small compared with the effective resistance of the voltage measuring device (potentiometer, electrometer or electronic voltmeter), the measured value will remain unaffected. Because of pressure contacts, the arrangement is also specially useful for quick measurement on different samples or sampling different parts of the sample.

Description of the experimental set-up

1. Probes Arrangement

It has four individually spring loaded probes. The probes are collinear and equally spaced. The probes are mounted in a teflon bush, which ensure a good electrical insulation between the probes. A teflon spacer near the tips is also provided to keep the probes at equal distance. The probe arrangement is mounted in a suitable stand, which also hold the sample plate. To ensure the correct measurement of sample temperature, the RTD is enbeded in the sample plate just below the sample. This stand also serves as the lid of temperature controlled oven. Proper leads are provided for the current and voltage measurement.

2. SAMPLE

Germanium crystal in the form of a chip.

3. OVEN

This is high quality temperature controlled oven suitable for Four Probe Set-up. The oven has been designed for fast heating and cooling rates, which enhances the effectiveness of the controller.

4. FOUR PROBE SET-UP, DFP-03

The set-up consists of three units housed in the same cabinet.

(i) Oven Controller

Platinum RTD (A class) has been used for sensing the temperature. A wheatstone bridge and an instrumentation amplifier are used for signal conditioning. Feedback circuit ensures offset and linearity trimming and a fast accurate control of the oven temperature.

Specifications of the Oven

Temperature Range : Ambient to 473K

Resolution : 1K

Stability : +0.5K

Measurement Accuracy :+1K(Typical)

Oven : Specially designed for Four Probe Set-Up

Sensor : RTD (A class)

Display : 31/2 digit, 7 segment LED with autopolarity and decimal indication

Power : 150W

(i) Multirange Digital Voltmeter

In this unit, intersil 3½ digit single chip A/D Converter ICL 7107 has been used. It has accuracy, auto

zero to less than 10 μV, zero drift-less than 1 μV/ °C, input bias current of 10 pA and roll over error of less than one count. Since the use of internal reference causes the degradation in performance due to internal heating, an external reference has been used.

Request
Callback

Product Details:

Measurement of Magnetoresistance of Semiconductors

Measurement of Magnetoresistance of Semiconductors

It is noticed that the resistance of the sample changes when the magnetic field is turned on. The phenomenon, called magnetoresistance, is due to the

fact that the drift velocity of all carriers is not same. With the magnetic field on; the Hall voltage V=E t=|vx y H| compensates exactly the Lorentz force for carriers with the average velocity; slower carriers will be over

compensated and faster one under compensated, resulting in trajectories that are not along the applied field. This results in an effective decrease of the mean free path and hence an increase in resistivity. Here the above referred symbols are defines as: v = drift velocity; E = applied electric field; t = thickness of the crystal; H = Magnetic field.

Experimentental Set-up for Magnetoresistance

The set-up consists of the following:

1. Four probe arrangement

2. Sample: (Ge: p-type)

3. Magnetoresistance set-up, DMR-01

4. Electromagnet, EMU-50V

5. Constant Current Power Supply, DPS-50

6. Digital Gaussmeter, DGM-102

(1) Four Probe arrangement°

It consists of 4 collinear, equally spaced (2mm) and individually

spring loaded probes mounted on a PCB strip. Two outer probes for

supplying the constant current to the sample and two inner probes

for measuring the voltage developed across these probes This

eliminates the error due to contact resistance which is particularly

serious in semiconductors A platform is also provided for placing the

sample and mounting the Four Probes on It.

(2) Sample

Ge Crystal (n-type) dimensions: 10 x 10 x 0.5mm.

(3) Magnetoresistance Set-up, Model DMR-01

This unit consists of a digital millivoltmeter and constant current

power supply The voltage and probe current can be read on the same

digital panel meter through a selector switch.

(a) Digital Millivoltmeter

lntersil 3½ digit single chip ICL 7107 have been used. Since the use of

internal reference causes the degradation in performance due to

internal heating an external reference have been used. Digital

voltmeter is much more convenient to use, because the input voltage

of either polarity can be measured.

Specifications

Range : 0-200mV (100μV minimum)

Accuracy : ±0.1% of reading ± 1 digit

(b) Constant Current Power Supply

This power supply, specially designed for Hall Probe, provides

100% protection against crystal burn-out due to excessive

current. The supply is a highly regulated and practically ripple

free dc source.

Specifications

Current : 0-20mA

Resolution : 10μA

Accuracy : ±0.2% of the reading ±1 digit

Load regulated : 0.03% for 0 to full load

Line regulation : 0.05% for 10% variation

The details of other sub-units can be had from their respective data-sheets.

Request
Callback

Product Details:

 

Electron Spin Resonance Spectrometer

Features

• FET based marginal R.F. Oscillator

• Digital display of frequency

• Excellent peaks display

• Digital display of Helmoltz Coil Current

• Compatible with general purpose CRO in X-Y mode

Introduction

In recent years Magnetic Resonance has developed into a very useful and powerful tool in solid state research. In this method, use is made of the Zeeman interaction of the magnetic dipoles associated with the nucleus or electron, when placed in an external magnetic field. Accordingly, they are identified as NMR (Nuclear Magnetic Resonance) or ESR (Electron Spin Resonance). This form of spectroscopy finds many applications in the investigation of crystal structures, environmental effects, dynamic effects, defects in solids and in many diverse branches of Physics, Chemistry and Biology.

Elementary Magnetic Resonance

We know that the intrinsic angular momentum (spin) of the electron Scouples with the orbital angular momentum of the electron L to give a resultant J and this coupling gives rise to the ‘fine structure’ of the spectra. Further, under the influence of an external magnetic field (H) each of the level will split into (2j+1) sublevels (Zeeman effect) and the splitting of a level will be

DE = (gμ0H)mj

where μ0 is the Bhor magneton, g is the Lande’ g-factor and mj is the magnetic quantum number. As can be seen, the splitting is not same for all levels; it depends on the J and L of the level (s=½ always for one electron). However, the sublevels will split equally by an amount

DE = gμ0H or = hn0

where n0 is the frequency of the system. Now if the electron is subjected to a perturbation by an oscillating magnetic

field with its direction perpendicular to the static magnetic field and its frequency n1 such that the quantum hn1 is equal to E=hn0, we say that there is a resonance between n1 and n0. This will induce transition between neighbouring sublevels (mj = ±1) and in turn will absorb energy from oscillating field. Thus, at resonance, we get a peak due to the absorption of energy by the system.

Experimental Technique

If we consider a free electron and substitute the proper value of constants in the equation: g = 2.00, μ0 = 0.927X10- 20 erg/gauss & h = 6.625 X l0-27 erg sec, we get

n 0—= 2.8MHz/gauss

H0 That is ESR can be observed at radio frequencies in a magnetic field of a few gauss or in the microwave region in a magnetic field of a few kilogauss. The latter alternate has many advantages: improved signal-to-noise ratio, high resolution etc. and is always preferred for accurate work, though it is very sophisticated and expensive. However, if the basic understanding of the subject is the main criteria as is usually the requirement of class room experiments, the observation of ESR in low magnetic field and in a radio frequency region makes it a lot simple, inexpensive and

within the reach of every post-graduate laboratory.

Description of the ESR Spectrometer

A block diagram of the ESR Spectrometer is given below in Fig. 1, and a brief description follows.

 

Request
Callback

Product Details:

Product Description

Features

·         Suitable for1H and11F nuclei

·         FET based marginal Oscillator

·         Digital Display of frequency and current

·         Clear display of resonance peaks

·         Compatible with general purpose CRO

Introduction

Nuclear Magnetic Resonance (NMR) was discovered by Bloch and Purcell in the year 1945. Over the years it has developed into a very useful and powerful tool in solid state physics, chemistry and biology. In medical application this technique, under the name Magnetic Resonance Imaging (MRI) has been developed as an excellent imaging method for clinical diagnosis. In this method use is made of Zeeman interaction of the magnetic dipoles associated with the nucleus when placed in a external magnetic field.

Elementary Magnetic Resonance

An atom whose nucleus has a nulcear spin I will have a magnetic moment as follows

= g_nI (1)

where _nis nuclear magneton, and g is g-factor. Under the influence of an external static magnetic field (H), these nuclear magnets can orient in distinct directions. Each spin orientation corresponds to a particular energy level given by

E = g_nHm_j(2)

with mj= -I, -(I-1), ...............(I-1), I

where mjis magnetic quantum number

The splitting of levels will therefore be-

DE = g_nH or = hn₀ (3)

where n₀is the r.f. frequency applied perpendicular to the static magnetic field. Now if the spins are subjected to a purturbation by an oscillating magnetic field with its direction parallel to the static magnetic field and its frequency n₁such that the quantum hn₁is equal toDE = hn₀, we say that there is a resonance between n₁and n₀. This will induce transition between neighbouring sub levels (m_j=I) and in turn will absorb energy from the oscillating field. Thus, at resonance, we get a peak due to the absorption of energy by the system.

Experimental Technique

In our experiment the NMR signals of Hydrogen nuclei and Fluorine nuclei are detected. Both have only two possible orientations in reference to static magnetic field H since both have proton spin I = 1/2. The sample is placed in an r.f.coil located between the gap of homogeneous magnetic field H. In order to exactly match equation (3), H is modulated at constant frequency (50Hz in our case) by using two modulation coils. Each time when the matching (resonance) condition (Eq. 3) is fulfilled, energy is absorbed from the r.f.coil due to the spin transition.

 

Request
Callback

Product Details:

 

Study of Thermoluminescence of F-centers in Alkali Halide Crystals

Pure alkali halide crystals are transparent throughout the visible region of the spectrum. The crystals

may be colored in a number of ways

(1) by the introduction of chemical impurities

(2) by introducing an excess of the metal ion

(3) by X-ray, g-ray, neutron and electron bombardment

(4) by electrolysis

Colour centres produced by irradiation with X-rays

When a X-ray quantum passes through an ionic crystal, it will usually give rise to a fast photo-electron with an energy of the same order as that of the incident quantum. Such electrons, because of their small mass, do not have sufficient momentum to displace ions and therefore loose their energy in

producing free electrons, holes, excitons and phonons. Evidently these while moving near the vacancies form trapped electrons as well as trapped holes. The trapped-electron or trapped-hole centres so formed can be destroyed (bleached) by illuminating the crystal with light of the appropriate wavelength or warming it.

Thermoluminescence

Important information about the colour centres can be obtained by measuring the changes that occur when a coloured crystal is gradually heated. As the temperature is raised electrons and holes escape from their

traps at an increasing rate. The freed charges can recombine with each other or with other defects and give out luminescence by recombination.

The resulting thermoluminescence or ‘glow’ reaches maximum and then decreases to zero as the supply of trapped electrons or holes becomes exhausted. The plot of luminescence intensity verses temperature, taken

at a constant heating rate, is called the ‘glow curve’. It may contain one or many glow peaks, depending upon whether there are one or several different kinds of traps.

From the glow curve one determine the trap depth; the deeper the trap, the higher the temperature of the glow peak. A correlation between the temperature at which thermoluminescence occurs and the temperature at which particular band bleach can give valuable information about specific

centres. Typical results obtained from this set-up for

KCl crystal are shown in figure.

The experiment consists of the following

EXPERIMENTAL SET-UP FOR CREATING

THERMOLUMINESCENCE

(1) Sample: KBr or KCl single crystal

(2) Thermolumniscence Temperature Meter, TL-02

·        Digital Thermometer

·        Oven Power Supply

(3 Sample Holder

(4) Thermoluniscence Oven (0-423K)

(5) Black Box

FOR MEASUREMENT OF LUMINESCENCE

INTENSITY

(1) Photomultiplier tube: 931A

(2) PMT Housing with biasing circuit and coaxial cables etc.

(3) High Voltage Power Supply, Model: EHT-11

Output : 0-1500V variable (1mA max.)

Regulation : 0.05%

Display: 3½ digit 7-segment LED

(4) Nanoammeter, Model DNM-121

Range : 100nA to 100mA full scale in 4 ranges

Accuracy : 0.2%.

Display: 3½ digit 7-segment LED

 

Request
Callback

Product Details:

Product DescriptionWith the help of skilled professionals and good knowledgeable experience, we are involved in supplying, exporting and manufacturing quality-assured spectrum of Thermolumniscence Irradiation Unit in Roorkee, Uttarakhand, India.

Experiment:
* Microcontroller based menu driven
* Cost effective solution
* No radiation hazard
* High quality double stage rotary pump
* Long life tesla coil
* Fully self contained

Study of Thermoluminescence in alkali halide crystals need creation of F-centres (colour centres) in alkali halide crystals. To produce the F-centres, the crystals are exposed to ionizing radiation which in turn causes the loss of electron from halide ions. An electron then becomes trapped in the halide ion vacancy. The color is the result of the absorption of a photon by the trapped electron and excitation from the ground state to an excited state for the F-center. This is a classic case of particle in a box. 

The source of ionizing radiation could be X-rays, electrons, gamma rays etc. These techniques are too Expensive and unaffordable for normal laboratories. Another method, although little less efficient, is by keeping Alkali halide crystals under low pressure, in the proximity of high Voltage. This in turn produces F-centres in the crystals.

This later technique has been adopted in this set up to make it economical and affordable for all laboratories. The setup is complete in itself and can be used straight away.

Request
Callback

Product Details:

 

Hall Effect experiment consists of the following:

(a) Hall Probe (Ge Crystal);

·         Material: Ge single crystal n or p-type

·         Resistivity: 8-10 Ωcm.

·         Contacts: Spring type (solid silver)

·         Zero-field potential:<1mV (adjustable)

·         Hall Voltage: 35-60mV/10mA/KG

(b) Hall Probe (InAs)

·         Contacts: Soldered

·         Rated Control Current: 4mA

·         Zero Field Potential:<4mV

·         Linearity (0-20KG): ±0.5% or better

·         Hall Voltage: 60-70mV/4mA/KG

Hall Effect Set-up (Digital), DHE-21

DHE-21 is a high performance instrument of outstanding flexibility. The set-up consists of a digital millivoltmeter and a constant current power supply. The Hall voltage and probe current can be read on the same digital panel meter through a selector switch. It consists of the following:

(i) Digital Microvoltmeter:

·         Range: 0-200mV (Resolutio 100μV)

·         Accuracy: ±0.1% of reading ±1 digit

·         Impedance: 1Mohm

·         Display: 3½ digit, 7segment LED

(ii) Constant Current Generator:

·         Current: 0-20mA (Resolution 10μA)

·         Display: 3½ digit, 7segment LED

·         Accuracy: 0.25%; ±1 digit

·         Load regulation: 0.03% for 0 to full load

·         Line regulation: 0.05% for 10% variation

Electromagnet, EMU-75 or EMU-50V
Constant Current Power Supply, DPS-175 or DPS-50
Digital Gaussmeter, DGM-102

 

 

Request
Callback

Product Details:

 

 

 

Features:

Perfect finish

Safe to use

Easy maintenance

 The apparatus consists of the following:

a) Hall Probe-Silver (HP-Ag):

Material: Silver Strip (8 x 6 x 0.05 mm)

Contacts: Press type for current

Spring Type for Voltage

Hall Voltage: ~17 µV/10A/10KG

b) Hall Probe-Tungsten (HP-W):

Material: Tungsten Strip (8 x 6 x 0.05 mm)

Contacts: Press type for current

Spring Type for Voltage

Hall Voltage: ~15 µV/10A/10KG

c) High Current Power Supply, Model PS-20A:

Range: 0-20A continuously variable

Accuracy: ±0.5%

Regulation: ±0.5% for ±10% variation of mains

Display: 3½ digit, 7 Segment LED

d) Digital Microvoltmeter, DMV-001:

Range: 1mV, 10mV, 100mV, 1V & 10V with 100% over-ranging.

Resolution: 1μV.

Accuracy: ±0.2%.

Stability: Within ±1 digit.

Input Impedance: >1000MΩ (10MΩ on 10V range).

Display: 3½ digit, 7 segment LED with auto .polarity and decimal indication

e) Electromagnet, Model EMU-75T:

 

Pole Pieces: 75mm tappered to 25mm

Mag. Field: 17KG ±5% at 10mm airgap

Energising Coils: Two of approx. 13W each

Power: 0-90Vdc, 3A, for coils in series

0-45Vdc, 6A, for coils in parallel

f) Constant Current Power Supply, Model DPS-175 

g) Gaussmeter, DGM-202

 

 

 

 

Request
Callback

Product Details:

 

Mechanical Tension Meter T1 Series

The  tension  meter  T1  Series  is  used  to  accurately  measure  the  running  line  tensions  on  all  kinds  of  wires (copper,  aluminum,  plastic  etc.,).  Cotton  Thread  and  fibers.  With  precise  jeweled (Ruby  Bushing)  movements,  precision  ball  bearing  mounted  rollers  and  a  built-in  damper,  the  T1  Tension  Meter  completely   eliminates  the  vibrations  and  resistance  caused  by  the  instruments  itself,  providing  reliable,  accurate  and  steady  tension  readings  even  as  it  fluctuates. 

The  measurement  range  of  this  tension  meter  will  starts  from  0  grams  to  3000  grams.  Measuring  unit  in  Newton  also  available.  The  T1  Tension  Meter  completely  eliminates the  vibrations.

We are engaged in providing a wide gamut of T1 Series Mechanical Tension Meter to our prestigious clients. Our given tension meter completely eliminates the vibrations and resistance caused by the instrument itself, providing reliable, steady and accurate tension readings even as it fluctuates. This mechanical tension meter is used to accurately measure the running line tensions on all kinds of wires. The offered T1 Series Mechanical Tension Meter is manufactured by our adept professionals using advanced techniques and excellent quality factor inputs.

Measuring unit in Newton also available.

Casing Material : ABS plastic

Specifications are subject to change without notice.

 

Request
Callback