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Laboratory Instruments – Repair and Maintenance – 18, 19 December 2007 1

Understanding Instrument

andInstrumentation

State Level w orkshop on

 “Repair and Maintenance of Laboratory Instruments” 

18, 19 December 2007.

Jayant Kirpekar, (Electronics Engineer)Department of Instrumentation Science,University of Pune, Pune 411 007.

email – jbk@usic.unipune.ernet.in

Laboratory Instruments – Repair and Maintenance – 18, 19 December 2007 2

What is an Instrument?

Tool – like a screw driver,

Gadget – like a remote control for a TV set,

Device – like a power supply,

Apparatus – like a distillation plant,

Machine – like a centrifuge,

Mechanism – like a rock and pinion type gear

Equipment – washing machine,

OR anything else –

Then w hat is laboratory instrument?

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A Laboratory Instrument may have -

Some thing as an input – Input Signal from user

Voltage / Current,

Speed, Colour, Light

pH / Conductivity . . . . .

Some thing to work w ith this input – Processing

Amplify,

Filter,

Convert to other form . . . . . . .

Some output – End product back to user

Display end result,

Control some device,

Make it available for o ther instrument . . . . . . .

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Laboratory Instrument – overview

Mechanical – Single Pan Balance, Optical Bench

Electrical – Oven, Furnace, Water bath

Electromechanical – Magnetic Stirrer, Centrifuges, Shakers

Optical – Microscopes, Spectrometer

Electronic –Signal generator, Multimeter, CRO, Pow er supplies,

Frequency Counters, Stabilizers, UPS

Opto-Electronic – Lux(Light) meter, Colorimeter

Chemical – pH meter, Conductivity meter, Water quality Analyser

Analytical – Spectrophotometer, Flame photometer

Other – OHP, X-Y Recorders, Experimental Gadgets,

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Instrument a general block diagram

InputStage

ProcessingSignal

OutputDisplay

PowerSupply

ControlSettingsInformation ?

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Basic Instrument – Power supply Rectifier and Filter

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Basic Instrument – Power supply Regulator

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Basic Instrument – CV / CC Power supply

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Basic Instrument – Analog Multimeter Voltage Measurement

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Basic Instrument – Analog Multimeter Current Measurement

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Basic Instrument – Analog Multimeter Resistance Measurement 1

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Basic Instrument – Analog Multimeter Resistance Measurement 2

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Basic Instrument – Analog Multimeter Simpson 260M

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Basic Instrument – Digital Multimeter Block Schematic

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Basic Instrument – DMM Voltage Measurement

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Basic Instrument – DMM Current Measurement

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Basic Instrument – DMM Resistance Measurement

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Basic Instrument – Signal Generator (Transistorized)

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Basic Instrument – Signal Generator (IC based)

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Advanced Instrument – Oscilloscope (General Purpose)

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Advanced Instrument – Oscilloscope (Duel trace)

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High impedanceAmplifier

TEMPERATURE

Level ShifterAmplifier

Analog toDigital

Converter14.00

ZERO

GAIN

Analytical Instrument – pH meter

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Analytical Instrument – Water Quality Analyser

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Analytical Instrument – Photoelectric Colorimeter

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Advanced Analytical Instrument – Spectrophotometer

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Advanced Analytical Instrument – Flame photometer 1

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Advanced Analytical Instrument – Flame photometer 2

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DC

AC

~ =

+ -

DC

AC

~=

LINE FILTER

BATTERY

CHARGER

BATTERY

INVERTER

SWITCH

Normal operationBackup operation

Other Instrument – Uninterrupted Power Supply

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For effective use and repair/maintenanceof an instrument, we must-

Know the instrument.

Try to understand the purpose of the instrument.

Find out basic blocks of the instrument.

What is the relationship of each block with the other?

Understand how it is to be operated?

Do’s and Don'ts with the instrument.

Limitations of the instrument.

Cost of the instrument?

Who may help for the instrument.

How? Through Service Manual of the Instrument.

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