Converter 12 Vdc to 230 Vac or Inverter

As shown in the Inverter circuit diagram obove , Its used as the oscillator stage astable multivibrator contained in IC1, a CMOS 4047 (this cult series 40xx series) by varying the resistance value of R1 trimmer (220 k total resistance) can vary the oscillation frequency of 40 Hz to 70 Hz square wave, phase shifted by 180 °,  Output pin 10-11 will drives two NPN transistors TR1-TR3, which in turn is fed to the TR2-TR4.
The diodes DS2-DS3, mounted on the output transistors TR2-TR4 are used to protect against voltage surges appearing across the windings V 9 + 9 V transformer T1. For the transformer T1, I used an ordinary mains transformer (primary 230 V so) with a secondary dual 2 x 9 V.

List of Inverter components:
R1 ……. 220 k trimmer
R2 ……. 330 k
R3 ……. 680
R4 ……. 2.2 k
R5 ……. 2.2 k
C1 ……. 4.7 nF polyester
C2 ……. 220 uF electrolytic
DS1 ….. 1N4004
DS2 ….. 1N4004
DS3 ….. 1N4004
DL1 ….. LED
TR1 ….. BC184 NPN
TR2 ….. NPN BDX53C
TR3 ….. BC184 NPN
TR4 ….. NPN BDX53C
IC1 …… 4047 CMOS
T1 …….. transformer sector 80 VA primary 230 V 0.35 A / Secondary 2 x 9 V 3.5 A
S1 ……. switch

Note :
Two final power TR2-TR4 should be mounted on the right size heatsink, otherwise they will overheat. You can choose from MJ4033 – MJ3007 or more, provided that the NPN.
The maximum power output that can be used depending on the size of the core of the transformer T1, the VA is: with 50 VA can be taken in the secondary 230 V 0.2 A (current consumed by the end will be 4 A) with 90 VA can be taken on the secondary 230 V 0.4 a (current consumed by the end will be 7 A).
To power the circuit from the 12V battery, it will take over at least 1.8 millimeters in diameter, to avoid loss by Joule effect.