how to build an inverter part2

Hello guys, hope you have all been fine and hope you enjoyed the last post, sorry this is coming a bit late but I hope you enjoy.
          This post will be based on building a square wave inverter using a 555timer IC and later we see how to convert it to something nearer to a sine wave inverter.
    Then at the long run build a pure sine wave inverter using (DSP) digital signal processors or microcontrollers I.e getting the pure sine wave by coding. And the code will be available and explanatory God willing.

Note: This is an inverter built on push pull transistor stage.

As explained before an inverter has 3 stages after the battery.

1. Oscillatory stage. ( we use 555 timer IC here )

2. MOSFET stage.

3. Transformer stage.

      Oscillatory stage based on 555timer chip.

    What is a 555 timer chip

 A 555 timer chip or IC is a timer IC that can be used in two modes either

1. Monostable

2. Astable

 We will be using the 555timer IC in the astable mode as to the fact that in this mode it acts a multivibrator or oscillators. Which we need to drive the MOSFET stage in other to get fast switching between a high and a low.
  Note the output of the 555timer is a square wave and this gives an advantage to the MOSFET in that it makes it operate in two modes

1. Saturation mode
2. Cutoff mode

 These two modes makes the MOSFET transistor stable and does not make it heat too much if you don't draw too much current from it in that when the input is a 1(on) it comes on and acts in saturation mode, then when it is 0(off) it acts in cutoff mode and thus makes it stable.

Picture of a 555timer ic

      MOSFET STAGE

 This is the stage that helps us to drive our transformers and it helps us do the fast switching as to the fact that a transformer works on a.c signal. So with this fast on and offs it makes the transformer commits because a transformer does not conduct on d.c signals.

       Things to consider when choosing a MOSFET.

When choosing a MOSFET one need s to consider the frequency and the current coupled with the voltage we will like to operate the inverter with. Who h could either be 12v , 24v,  36v, and 48v. The more the voltage the more rugged the inverter is and the lesser the losses while switching the MOSFET stage.
    The MOSFET must be able to handle 50 to 60 hz switching and it must be fast and it must be able to handle the current we want to draw from it but it is better it is able to handle times 2 the current. And it must be able to handle the voltage as well.




Picture of a MOSFET type: irf3205 an n channel mosfet

      Transformer stage

 This is the final stage of a square wave inverter and and it does a job of amplifying the voltage gotten from the MOSFET from 12v which is what we will be using in our case to 220volts ac.and it does this by steeping up the voltage and reducing the current.

      Things to consider when choosing a transformer for an inverter

 We need to consider the power of the transformer. I.e can the transformer handle the power we want, the rating of the transformer must match the desired load to be used on and it is always better to make the transformer capable of handling 20℅ more than we intend to use it on. And we must consider the power factor also.

 Output signal

The rising edge is known also called a 1 while the falling edge ed s a 0

And the positive half is the more positve edge while the negative half is the more negative edge, let's leave it at that to avoid confusion.

  Circuit diagram and frequency calculation.

For a 555timer in astable mode the formulae is

F= 1.44 / (Ra + 2Rb)c

Ra= 4.7k
Rb= 120k
C= 0.1uf

And that's how we got our frequency of 50hertz.

Sorry guys pls use irf540n for the MOSFET. Irf3205 allows a maximum of 4volts on the gate....so i advice you use irf3205 that can still allow 10volts maximum.

Circuit diagram explanation

The first stage here is the oscillatory stage which is generated from a 555timer IC in as table mode. It outputs to us a square wave signal in a pulse which comes on 50times and goes off 50 times making a frequency of 50hertz. Then this signal is feed into the MOSFET stage but the bc547 connected in common emitter mode helps us to invert the signal coming which is either a1 or 0. As to the fact that it gives a phase change of 180° in this mode, so at MOSFET one if we have a 1 it commits and the bc547 that also received a 1 will invert it to 0 and the second MOSFET does not switch but when the 555timer signal is on low which is 0 the first MOSFET enters cutoff and with the help of the BC547 the 0 is inverted to 1 and we have a signal that goes on and off 50times in one second. I.e 50 times on and 50 times off.

   With these we get a a multivibrating signal out of the MOSFET which is feed into the transformer to be stepped up to 220volts.  

NOTE : law of persistence of vision (pov)  states that anything that tickets or moves more than 20times in one sexound the human eyes see it to be stable and that's why we don't see our a.c bulbs shake unless the frequency is extremely low which could damage your electrical appliances or makes you appliances misbehave or charge your phones faster like your small generator

      Materials that will be used.

1. 555timer ic.
2. Irf3205.
3. Bc547.
4. Transformer.
5. Resistor.
6. Capacitor.


Thank you for following this post I hope you enjoyed it on our next post we will be building a 500watts inverter close to pure sine wave.