MARX GENERATOR BASED HIGH VOLTAGE USING MOSFETs Submitted by:

CONTENTS Introduction Block diagram Marx generator principle Opto-isolator MOSFET 555 timer Schematic & Working of the project Advantages Applications Future scope Conclusion

Project overview The aim of this project is High voltage Marx generator implementation using MOSFET/IGBT stacks. The Marx generator is composed of 4 stages and each stage is made of MOSFET/IGBT stacks, two diode stacks, and capacitors. MOSFET/IGBT stack is used as a single switch. Diode stacks and inductors are used to charge the high voltage capacitor at each stage without power loss. The proposed Marx generator implementation uses MOSFET/IGBT stack with a simple 555 driver. This system structure gives compactness and easiness to implement the total system from a DC supply of 12V to get 48V.

Block diagram

Marx generator principle A number of capacitors are charged in parallel to a given voltage, V, and then connected in series by spark gap switches, ideally producing a voltage of V multiplied by the number, n, of capacitors (or stages). Due to various practical constraints, the output voltage is somewhat less than n×V.

Opto-isolator Opto coupler is a 6 pin IC. It is a combination of 1 LED and a transistor. Pin 6 of transistor is not generally used and when light falls on the Base-Emitter junction then it switches and pin5 goes to zero. If input of the diode is zero and other end of diode is GND then the output is one. When logic zero is given as input then the light doesn’t fall on transistor so it doesn’t conduct which gives logic zero as output. When logic 1 is given as input then light falls on transistor so that it conducts, that makes transistor switched ON and it forms short circuit this makes the output is logic zero as collector of transistor is connected to ground.

MOSFET The MOSFET (Metal Oxide Semiconductor Field Effect Transistor) is a Voltage controlled device.    This means that a voltage at the gate control the current flows from the drain to the source. There are three terminals: Gate - connected to the input device. Drain - connected to the positive, since electrons drain away to the positive. Source - the source of the electrons

Contd.. USES OF MOSFETS High power devices like motors and light bulbs give a large current output for a very tiny current input.   So a MOSFET can act as the interface between an integrated circuit that can give only a tiny current, and the motor that takes a big current.   In complimentary pairs they are used in hi-fi power amplifiers.   They produce less distortion as they are more linear than bipolar transistors. Integrated circuits, as they can be made very compact.

555 TIMER The 555 Timer IC is an integrated circuit (chip) implementing a variety of timer and multivibrator applications. The original name was the SE555 (metal can)/NE555 (plastic DIP) and the part was described as "The IC Time Machine". Depending on the manufacturer, the standard 555 package includes over 20 transistors, 2 diodes and 15 resistorson a silicon chip installed in an 8-pin mini dual-in-line package (DIP-8)

PIN DIAGRAM OF 555 The 555 timer IC is a simple 8 pin DIL package IC. It can: be used as a monostable be used as an astable source or sink 100mA use supply voltages of 5v to 15v disrupt the power supply - use a decoupling capacitor!