Wiring Diagram

Step up part of this inverter circuit using a transformer 12VCT/500VA in secondary and primary 0 - 220V. While the frequency is determined by the flip-flop which is set to 50 Hz.

Note:

•     Q7, Q8 and Q7x, Q8x require heat sink.


•     Output power of this dc dc converter is around 500 watts.


•     An optional 40A fuse can be added in circuit to the 12V supply line.


•     T1 can be a 12-CT-12V /250V/40A mains transformer.

It is recommended to Have a “Fuse” in the Power Line and to always have a “Load connected”, while power is being applied. The Fuse should be10 Amps per 100 watts of output. The Power leads must be heavy enough wire to handle this High Current Draw.

The 555 feeds its output (amplified by Q1 and Q2) to the input of transformer T1, a reverse-connected filament transformer with the necessary step-up turns ratio. Capacitor C4 and coil L1 filter the input to T1, assuring that it is effectively a sine wave. Adjust the value of T1 to your voltage. The output ( in watts) is up to you by selecting different components.

Input voltage is anywhere from +5V to +15Volt DC, adjust the 2700uF cap's working voltage accordingly. Replacement types for Q1 are: TIP41B, TIP41C, NTE196, ECG196, etc. Replacement types for Q2 are: TIP42B, TIP42C, NTE197, ECG197, etc.

The inverter circuit has a central component, the CMOS 4047, and converts a 12V DC voltage to 220V AC voltage. 4047 is utilised as a astable multivibrator. At pin 10 and 11 we find a rectangular symmetrically signal which is amplified by tow Darlington transistors T1 and T2 and finally reaches the secondary coil of a transformer network (2 x 10V/100VA). Primary coil terminals voltage is 220 alternative voltage. To obtain a better performance use a toroidal core transformer with reduced losses. With P1 the output frequency can be regulated between certain limits (50…400Hz).