Newnes Circuit Calculations Pocket Book

13

Transformers

13.1 Introduction

Transformers consist

of two

coils which

are

wound

on a

common

magnetic former,

and are

insulated from

one

another.

The

primary

winding

(see

Figure

13.1) is

connected

to an a.c.

supply

and the

output

is

taken from

the

secondary winding. Transformers

can

'step

up'

or

'step down'

a

voltage depending

on the

winding arrange-

ments.

They

are

also used

for

resistance

and

impedance matching,

coupling

one

circuit

to

another,

and for

isolating

one

circuit from

another since

the

primary

and

secondary windings

are not

intercon-

nected.

Alternating

primary

voltage

Figure

13.1

Secondary

output

voltage

13.2 Transformer actio ...