SMPS Design With IC TL494 in Push Pull Configuration Primary 12V DC @ 30W Secondary 220 V AC @ 65khz

In this instructable I'm demonstrating a basic switching power supply design using push pull configuration.

The switching power supply is designed to deliver a power of 30W. Input supply voltage is 12V DC and Output voltage is 220 V AC @ 60Khz.

BILL OF MATERIALS

NOTE : All resistors are 1/4 W

C1 22PF

Q1 25N120

Q2 25N120

R1 100K

R2 100K

R3 100K

R4 100K

R5 10K

R6 10K

R7 330E 1W

R8 330E 1W

R9 100E

R10 100E

R11 30W LAMP

T1 TRANSFORMER (REFER DESIGN)

U1 TL494

Transformer Primary = 12 V @ 60 W

Transformer Secondary = 230 V

Primary no. of turns = (Primary volts X 10^10)/(4 x frequency (Hz) X Core area (sq. mm) X flux density (Gauss) )

Primary no. of turns = (12 X 10^10) / (4 X 65000 X 69 X 1500 ) = 4.45 or 5 turns

Secondary voltage = 230 X 1.414 = 325.22 V

No. of turns in secondary = (Secondary Voltage / Primary voltage) / Primary no. of turns

= (325.22 / 12) X 4.45 = 120.6 turns

Wire used = 38 SWG for both primary and secondary windings.

38 SWG wire current capacity = 0.350 A

30 W @ 12 V ==> 30 /12 = 2.5 A

No. of conductors in primary = 2.5 / 0.350 = 7.14 , say 8 conductors.

Secondary can have 1 conductor to serve this power.

Transformer design summary

Core area = 69 sq. mm

Operating frequency = 65 khz

No. of turns in primary = 5 ( 5 + 5 as it is bifilar winding, center tap required for push pull configuration. )

Secondary turns = 120 or 121

38 SWG copper wire

Primary has 8 conductors with 5 turns two windings in bifilar winding.

Secondary has 1 conductor 120 turns.

Make the circuit as shown in circuit diagram.

Make the transformer as per design.

Supply voltage = 12.22 V

Current drawn from power supply = 2.45 A

Output voltage to load lamp = 225 V AC @ 65khz.