Electronic workshop

Dr. Imtiaz Hussainemail: imtiaz.hussain@faculty.muet.edu.pk

URL :http://imtiazhussainkalwar.weebly.com/

Lecture-5Inductors and Transformers

Inductors• Generally - coil of conducting wire– Usually wrapped around a solid core. If no core is

used, then the inductor is said to have an ‘air core’.

Symbols

4

Inductors

• Values specified in henries (H), millihenries (mH) and microhenries (μH).

• Inductor can be fixed value or variable.

Fixed Value Inductor Variable Inductor

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Inductor types

Molded inductor & air-wound inductor Adjustable air-wound inductor

Ferrite core toroidal transformer Iron powder toroidal inductorAir wound inductor

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Inductor ratings

• Wire gauge and physical size of the coil determine the current handling capacity.

• Core material will have a temperature dependence.

• Air is best, followed by iron powder, then ferrites.

7

Inductor handling

• Inductors are not polarized and may be installed in either direction.

• Mechanical stress due to lead bending should be minimized.

• Inductors in timing or frequency determining circuits should be installed in a mechanically rigid fashion.

Color Coding

Inductor Applications

• Speakers• Solenoid Valves• Resonant Circuits

Task#1

• An ideal inductor would exhibit zero resistance but a real inductor has some finite resistance.

• Inductors which have become open will show infinite resistance, whereas shorted inductors will show a resistance of zero Ohms.

• Take few resistors and check them for any faults.

Transformers• A transformer is a device that uses a pair of coils/windings to

manipulate AC voltage and current. • It uses the principle of mutual induction to either decrease or

increase the voltage/current at its input.

Transformers

Transformers

• The voltage/current at the output of the transformer is given by the following equation:

𝑉 𝑠

𝑉 𝑝

=𝑁 𝑠

𝑁𝑝

=𝐼𝑝𝐼 𝑠

Task#2

S N.o

Peak to Peak Input Voltage

Output Voltage Turn Ratio

1. 2. 3. 4. 5.

END OF LECTURE-5

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