HOW TO FACE

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HOW TO FACE VIVA VOCE EDC/WS LABS
Prof. K.APPA RAO ME(IISc),FIETE,MCSI.
Email apparao_kotha_at_hotmail.com Web site
www.freewebs.com/apparao_kotha Tel [phone]
9839, 040 3243 0039 (cell)
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COMMON QUESTIONS FOR EDC/WS
LABS
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WHAT IS THE DIFFERNECE BETWEEN THOERY
AND PRACTICE ?
Theory is abstract Practical is specific and
concrete.
Example
Type Carbon film CF Value 1000
ohms Tolerance 5 Wattage 1 watt. Style
axial. Size 4 x 20mm
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BASIC COMPONENTS
PASSIVE COMPONENTS R,L,C ACTIVE COMPONENTS
D,Q,Z,FET,SCR etc.

• COMMON QUESTIONS
• SYMBOLS, PHYSICAL IDENTIFIATION
• ELECTRICAL CHARECTERISTICS
• VI CURVES, PARAMETERS ß, a, ß, PIV,
• RELATION BTWN PARAMETERS.

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TOOLS USED
NOSE PLIER, CUTTER, SOLDERING IRON etc
INSTRUMENTS USED
VOLT METERS,MILLI AMMETRS MULTIMETERS,
DMM OSCILLOSCOPE, POWER SUPPLY, FUNTION GENERATOR
etc.
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QUESTIONS ON PASSIVE COMPONENTS
I HAVE ONLY 1/4 w RESITORS. I WANT 10K 1W.
HOW CAN I MAKE ?
SOLUTION 2.5 K 1/4w RESITORS 4 IN SERIES. OR 40K
1/4w RESITORS 4 IN PARALLEL.
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COLOR CODE OF RESISTORS.
WHAT IS COLOR CODE FOR 1.5K 5 (Br Gr, R ,
Gold) 82K 10 (Grey,R,Or Silver) 39 M 20
(Or, Wh, Bl ) 2.2 OHM ? (R,R, Gold, Gold).
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MEASUREMENTS ON PASSIVE COMPONENTS.

• AN ELECTROLYTIC CAPACITOR
• MFD measures 90 MFD.
• IS IT ACCEPTABLE ?
• YES
• Electrolytic capacitors will have
• Tolerance 20 to 40

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A RESITOR IN DIODE CHARACTERISTIC EXPERIMENT AS
SHOWN IS USED. What wattage rating is required ?
Maximum current 30/130ma Power dissipated in R
vxi30x30 900mw . Practical value 1watt
Change V , max current find R Wattage.
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QUESTIONS ON AMMETERS AND VOLTMETERS
WHAT IS INTERNAL RESISTANCE OF IDEAL AMMETER
? Ans ZERO. IDEAL VOLTMETER ? ANS
INFINITY. why ? justify

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QUESTIONS ON MULTIMETRS, DMM
IS ANALOG MULTI DC OR AC METER? HOW SEVERAL
RANGES ARE ACHEIVED? HOW CAN YOU CONVERT AMMTER
TO VOLTMETER ? WHAT IS LED / LCD ? WHAT CAN DMM
MEASURE? WHAT DO U MEAN BY 3 ½ DIGIT DMM?
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SPECIFIC QUESTIONS TO WORK SHOP LABMATERIALS
WHAT IS PCB ? WHAT IS DICLAD,SINGLE CLAD/ WHAT
IS CHEMICAL USED FOR ETCHING ? WHAT DRILL BIT
HAVE USED FOR R. WHAT IS SPEC OF SOLDERING
IRON. WHAT IS SOLDER MADE OF? WHAT IS FLUX ?WHY
DO U USE ? TYPES OF RESISTORS ,CAPACITORS,INDUCTOR
? SWICTHES,FERRITE CORES,KNOBS.
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COMMON QUESTIONS TO EDC/WORK SHOP LABINSTRUMENTS
OSCILLOSCOPE REGULATED POWER SUPPLY FUNCTION
GENERATORS MULTIMETER,DMM DC MOVING COIL V,ma
meters.
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KNOWLEDGE OF ELECTROMECHANICAL COMPONENTS.
FUSE, fast blow off/slow blow off.
function,construction. What is fuse
electrically? BINDING POST,SOCKETS,KNOBS, BANANA
PLUGS,BNC,CONNECTORS. WIRES/CABLESS/S,MULTI
STRAND. SHIELDED CABLES,HOOK UP WIRES.
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KNOBS screw,collet, concentric,
pointed, dials etc.for ¼,1/8 inch. SWITCHES
spst,dpst,sping loaded, rotary,
slide,toggle,lever, etc.. TRANSFORMERS
power,audio,radio, pulse, winding
wires,en cu wires. Coils air core, rf,
bifilar, RELAYSfunction. HARDWARE screws,nuts
sizes(BA/mm),head styles.
slot/star types.
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KNOWLEDGE OF OSCILLOSCOPE
SINGLE/DUAL TRACE modes XY, component tester
modes. Band width,rise time relation. Uses BLOC
K Diagram of CRO. Double beam/dual trace Why
sweep is saw tooth?
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SHOW YOUR KNOWLEDGE IN REPORT ? How ? ?
VERY SIMPLE Make it more practical in aim,
apparatus, procedure, description, curves, and
choosing measurement points. see a simple
example.
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AIM forward,reverse characteristics of given
diode under its ratings. APPARATUS
Components Si diode 1N 4007. 1no.
CF resistor 1K 5 1w..1no. insruments
DC regulated power supply0-30v..1no Dc
moving coil milli ammeter 30mafsd. 1no 3 ½
digit DMM LCD type 1no. others Bread
board, S/S hook up wires.
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IMPORTANT HINTS.
TALK POLITELY CONFIDENTLY. EXPLAIN WITH
FIGURES IF U CAN. BE PRECISE AND SHORT. DO NOT
BE IN HURRY TO ANSWER. YOU CAN DO WELL.
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ALL THE BEST.. BE PRACTICAL GOOD LUCK.. Prof.
K.Appa Rao.