The scheme of the inverter DC to AC 12 to 220 V. This inverter is suitable for power users who need an alternating voltage of 220 V with a total capacity of up to 100 watts.
The inverter consists of a master oscillator (symmetrical multivibrator for VT1, VT2) and the main circuit (VT3. .. VT8). Inverter operates as follows. After switching on DC power, master oscillator for VT1 and VT2 starts to generate control pulses. These pulses through R5 and W are applied to one arm of the power circuit, and by R6 and C4 – in the second.
When the collector VT1 – high level (logic “1”), and the collector VT2 – low (“0”), transistors VT4, VT6 and VT8 open, and current flows through the circuit: “+” power source – winding W1 ” – the transition of the collector-emitter VT8 – “-” the power supply. At this point, transistors VT3, VT5 and VT7 closed.
The next time the collector VT2 will be “1”, and the collector VT1 – “0”. Transistors VT3, VT5, VT7 open and current will flow through the circuit: “+” power source – winding W1 ‘- transition collector-emitter VT7 – “-” the power supply. Transistors VT4, VT6 and VT8 closed. Because of this, the primary winding of output transformer is applied an alternating voltage of rectangular shape, whose amplitude is approximately equal to the supply voltage. Generated in the magnetic field induces a magnetic secondary winding electromotive force, whose magnitude is determined by the number of secondary turns W2. Diodes VD1 and VD2 are designed to prevent surge of negative amplitude at the work of the master oscillator and diodes VD3 and VD4 prevent breakdown of power transistors in the power circuit at idle (no load in the secondary winding of the transformer).
Transformer wound on a magnetic circuit TV Sh36h36. The winding W1 ‘and W1 “are to 28 turns of PEL d2, 1 mm (each), and winding W2 – 600 turns of PEL d0, 59 mm. At first wound winding W2, and over it – winding W1’ and W2”. To achieve a good symmetry, the winding reel preferably at the same time, the two wires.
Note : Transistors VT5, VT7 and VT6, VT8 installed on two separate heat sinks without insulating pad.
To control the operation of the circuit it is desirable to include among the positive pole of power and the midpoint of the winding W1 ammeter with 10 A limit of measurement (show in the scheme above). It is designed to visually monitor the current flowing through the transistor power circuit. When you turn on the maximum load in the secondary winding of this current should not exceed 10 A. In the absence of the load must be less than 5 A. If when you turn on the inverter in the absence of the load current exceeds 10 A, which means that the sample (or incorrectly included) a either of the diodes VD3, VD4 or transistor power circuit. Adjustment of the inverter is to configure the master clock and by using an oscilloscope or frequency counter. Input of an oscilloscope (frequency) is connected to the collector of one transistor VT1 or VT2, and the generator is energized. With the help of RP frequency generator set of 50 Hz. Oscilloscope is desirable to control the shape and rectangular pulses. Tuned inverter is mounted in a suitable enclosure on the front panel which displays an ammeter, fuse holder, switch, oscillator, connect the load terminals and the battery power and battery indicators are included (red) and oscillator (green). The inverter can supply to the consumer with 100 watts for at least 2 hours when using the battery capacity of 44 Ah.