Counting and assemble the transformer for
in home lab.
Transformer is very important part of
power supply. It allow to transform the AC voltage
without loosing energy. Efficiency of transformer is 95 - 98%.
The weaknesses of transformer is big weight, coast, and
technologies problems with assembling.
Counting the transformer.
V1 - primary AC voltage 50-60
Hz (~120 V);
V2 - secondary AC voltage;
I2 - secondary current;
The power (P) of transformer: P = V1
x I1 = V2 x I2;
So I1 = V2 I2
The area (cm2) for window of the coil
= a x b. Approximately we can find it like P½
. So size a and b of the core = P¼ .
Transformer core is the set of iron’s slices
(picture 1). Find in Data Book the size of transformer
core b = a (cm)
bigger and closest to P¼
The quantity of the pieces n = a/d, where
d is width of one piece.
Find the quantity of the loops per one volt M.
Use the empirical formula: M = 50/P½ .
So quantity of the loops for primary coil of
transformer: w1 = V1 x M .
For secondary coil do same way:
w2 = V2 x M.
Diameter of wires in millimeters we can find from
the formula: d = .02 x I½
. So for primary
coil d1 =
.02 x I1½
secondary coil d2 =
.02 x I2½
Assembling the transformer.
Making the bobbin for the transformer coil with
the carton and glue
sizes of the core (picture 2).
Round the first coil on bobbin with wire d1
and quantity loops are w1 (picture 3).
Round the second coil on bobbin with wire d2
and quantity loops are w2 (picture 4, 5).
Setup the iron’s slices of transformer core in the
bobbin (picture 6 & 7).
Study name and pictures of the details above
recommend to use online book about electronics: