Design#1: How it Works
The first 50 W circuit may be understood with the following points:
Referring to the figure, transistors T1 and T2 along with the other R1, R2, R3 R4, C1 and C2 together form a simple astable multivibrator (AMV) circuit.
A transistor multivibrator circuit basically is composed of two symmetrical half stages, here its formed by the left and the right hand side transistor stages which conduct in tandem or in simple words the left and the right stages conduct alternately in a kind of a perpetual “motion”, generating a continuous flip flop action.
The above action is responsible of creating the required oscillations for our inverter circuit. The frequency of the oscillation is directly proportional to the values of the capacitors or/and the resistors at the base of each transistor.
Lowering the values of the capacitors increases the frequency while increasing the values of the resistors decreases the frequency and vice versa. Here the values are chosen so as to produce a stable frequency of 50 Hz.
Readers, who wish to alter the frequency to 60 Hz, may easily do it by just changing the capacitor values appropriately.
Transistors T3 and T4 are placed at the two output arms of the AMV circuit. These are high gain; high current Darlington paired transistors, used as the output devices for the present configuration.
The frequency from the AMV is fed to the base of T3 and T4 alternately which in turn switch the transformer secondary winding, dumping the entire battery power in the transformer winding.
This results in a fast magnetic induction switching across the transformer windings, resulting the required the mains voltage at the output of the transformer.
Parts Required
R7, R8 = 22 Ohms, 5 Watt
D1, D2 = 1N5402 or 1N5408
Sundries: Metallic box, fuse holder, connecting cords, sockets etc
Testing and Setting Up the Circuit
Initially do not connect the transformer or battery to the circuit.
Using a small DC power supply power the circuit.
If everything is done rightly, the circuit should start oscillating at the rated frequency of 50 Hz.
You can check this by connecting the prods of a frequency meter across T3’s or T4’s collector and the ground. The positive of the prod should go to the collector of the transistor.
If you don’t own a frequency meter, never mind, you do a rough checking by connecting a headphone pin across the above explained terminals of the circuit. If you hear a loud humming sound, will prove that your circuit is generating the required frequency output.
Now it’s time to integrate the battery and the transformer to the above circuit.
Connect everything as shown in the figure.
Connect a 40 watt incandescent lamp at the output of the transformer. And switch ON the battery to the circuit.
The bulb will immediately come ON brightly…..your homemade 50 watt inverrer is ready and may be used as desired by for powering many small appliances whenever required.
Design#2: 50 Watt Mosfet Inverter Circuit
The circuit explained above involved power transistors now let's see how the same concept may be utilized with mosfets making the configuration much easier and straightforward, yet more robust and powerful.
Rest of the stages are pretty much the same, in the earlier circuit we saw the involvement of a transistor based astable multivibrator for the generation of the required 50 Hz oscillations, here too we have incorporated a transitor operated AMV.
The earlier circuit had a couple of 2N3055 transistors at the output and as we all know driving power transistors efficiently requires proportionate amount of base drive, relative to the load current, because transistors depend on current drive rather than voltage drive, in contrast to mosfets.
Meaning, as the proposed load becomes higher, the base resistance of the relevant output transistor also gets dimensioned accordingly for enabling optimal amount of current to the base of the transistors,
Due to this obligation, in the previous design a additional driver stage had to be incorporated for facilitating better drive current to the 2N3055 transistors.
However when it comes to mosfets, this necessity becomes completely insignificant.
As can be seen in the given diagram, the AMV stage is instantly preceded by the relevant gates of the mosfets, because mosfets have very high input resistance, which means the AMV transistors wouldn't be unnecessarily loaded and therefore the frequency from the AMVwouldn't be distorted due to the integration of the power devices.
The mosfets are alternately switched, which in turn switches the battery voltage/current inside the secondary winding of the transformer.
The output of the transformer gets saturated delivering the expected 220V to the connected loads.
Parts List
R1, R2 = 27K,
R3, R4 = 220 Ohms,
C1,C2 = 0.47uF/100V metallized
T1, T2 = BC547,
T3, T4 = any 30V, 10amp mosfet, N-channel, or a couple of IRF540
Diodes = 1N5402, or any 3 amp rectifier diode
Mosfet: IRF540
Transformer = 9-0-9V, 8 amp
Battery = 12V,10AH
Video showing the Testing process of the 50 watt inverter circuit:
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Loki says
Can i use two different mosfet one is 37 amp other is 50 amp
Swag says
yes you can!
Lm324n says
Can i use 12k resistor and 2.2 uf cap for getting 50hz frequency
Swag says
you will have to confirm the results practically with some experimentation
Lm324n says
Can i use ferrite transformer instead of iron transformer?
The circuit is working perfect thanku
Swag says
ferrite trafo will require high frequency, and high frequency cannot be used for driving home appliances so it cannot be possible, unless you apply additional complex stages
Lm324n says
Sir why there is no resistor on the gate of the mosfet because there are resistor for mosfet in your ‘Single Transformer Inverter/Charger/Changeover Circuit.’
Swag says
because we already have them in the form of R3/R4…so it’s not required
Lm324n says
Can i use 13001 transistor instead of bc 547?. and what about the efficiency
Swag says
it will work but it is unnecessarily huge for the application…
Lm324n says
Sir can i use 70t036h smd mosfet it has 30v and 60 ampere capability
Swag says
yes you an use it…
Aabhishek Sharma says
Hi sir, I have a similar design but different circuit, today after replacing the transformer and remaking the circuit with new parts, when I tested the output it should 225v but by replacing multimeter test probes sides, it showed 269v, why this difference in voltage showing after replacing multimeter probes side on output.
Swag says
Hi Aabhishek,
I think your meter is malfunctioning, I would advise you to buy a good quality, costlier multimeter and check it with it. and I hope you are using the AC range of the meter.
Aabhishek Sharma says
Yes sir of course I’m using AC range, I know how to use it, ok thanks for advice I try to check this using different multimeter of Google quality. I pray to God that inverter is good just multimeter is malfunction.
Thanks.
Swag says
Hi Aabhishek, inverter cannot be wrong, because it cannot produce two voltages together…it is the meter which is giving wrong results.
manash Athparia says
I made this inverter circuit but thee voltage drops too much when load is connected.
Swag says
the output power will be as per the wattage of the transformer and the battery, upgrade these two to get higher wattage capacity at the output
manash Athparia says
I have used 12-0-12 8A transformer and 12v 7ah battery.
Swag says
check current by inserting a DC ammeter between the battery positive and inverter positive, and make sure the battery is fully charged at 14V.
the current reading will tell you whether the trafo is actually accepting the required amount of battery current or not. also check the voltage across the gate of each mosfet with reference to ground, it must be around 6V DC.
Swag says
By the way the trafo should be 9-0-9V as mentioned in the article.
Aman thakur says
Sir I have 9 0 9 transformer two irf 630 mosfet four 2n3055 four tip127 transistor can i made inverter with these and how
Swagatam says
Aman, yes you can use an inverter with these parts, but the trafo must be rated at minimum 5 amps, and you will also need a 12V/7 AH battery for the operations.
Aman thakur says
Sir please give me circuit digram of your above inverter
Surianarayanan Alagar says
respected sir,
i need one help, i draw the your circuit from proteus softwre and how to check output from your circuit
Swagatam says
Hi suria, sorry I won't able to help you in this regard since I do not personally use or rely on softwares for simulation…
Abhishek Sharma says
Hi sribasu,
The battery wattage , mosfet and transformer ampere rating decides the output wattage of inverter.
Sribasu says
I already developed such MOSFET based square wave inverters. But they ate capable of driving at most 5 watts CFL. Is there a way to improve the oitput wattage of these inverters? Which component in this circuit actially drives the wattage rating of this inverter?
Swagatam says
the mosfet and transformer wattage are primarily responsible for the power delivery, not forgetting the battery AH which ensures that the load is able to run at the rated maximum power without dropping the voltage.
Abhishek Sharma says
On the post which I have commented on.
Abhishek Sharma says
Hi sir can I use zener 4148 diode as safety diode and can I then operate inverter as online UPS (not using computer using for inverter purpose)
Swagatam says
which circuit are you inferring to??
Abhishek Sharma says
I'm saying about this circut. Please reply fast.
Swagatam says
which circuit, the above 50 watt inverter on this page??…1N4148 cannot be used, you must use a 3 amp diode as mentioned in the article.
Spike says
Can u pls provide me a simple 50Hz square wave to sine wave converter circuit..
Swagatam says
you can check out this
https://homemade-circuits.com/2013/04/how-to-modify-square-wave-inverter-into.html
Aditi says
As I can seen from your circuit this a astable multivibrator with MOSFET …can you tell us what's the use of MOSFET in this circuit ??? Please explain in detail …
Swagatam says
it converts the low current astable pulses into high current induction inside the connected trafo winding
Unknown says
hai swagatam sir,
if we are using 2 CFL bulb by this Inverter circuit with 12v 10AH battery then till how much the bulb will glow.
Aditi says
I have 12-0-12 , 3A transformer and I'm interested in only to glow a 10W blub ..and I have only 5Volt 1.5A supply ..can I make a inverter with those specifications????
And what's the role of transformer current rating for example I have 3 A transformer .. does that mean It will work only above 3 A battery supply or something else please explain it .. thanks in advance
Swagatam says
the 3A is the maximum current producing or handling limit of the transformer, it has nothing with the battery current, rather it is related to the load current which must not exceed 2A.
Ashy Abhi says
Will this circuit work when I apply 5V and 1.5A battery and my transformer is 12-0-12 , 3A ..I want to glow only 10W blub ..will it work ????
Swagatam says
No it won't, the battery and the trafo rating must be similar.
Ashy Abhi says
Hey I want to make 10W inverter so what will be the battery and transformer ratings for this ???
Btw I have 12-0-12 3A transformer so please tell me suitable battery for this to glow only 10W blub
Swagatam says
with a 12V /3a trafo you can use a 12V / 7AH battery
Ashy Abhi says
I'm beginner please tell me what's is the meaning of 9-0-9 and 12-0-12 please explain this in detail
Swagatam says
that's 3 wire outputs from the transformer primary winding, when 220V is applied from the other side…these 3 wires on the other side will produce 9V-and-9V between the central 0V wire and the outer two wires, hence it's termed as 9-0-9, or similarly 12-0-12 when it's 12V
Aminu Yahaya Ibrahim says
Sir it wasn't in your blogs, and I search for it now, but I couldn't see it.
Sir could you help me with one charging circuit that has battery full cut off feature.
If my transfo rated 20A, and the outertaps are 7.2 convine together to get 14.4, when the battery AH is 200 what circuit is suitable for this project?
thanks for your kind help.
Swagatam says
Aminu, you can try the second circuit from the following link
https://homemade-circuits.com/2011/12/how-to-make-simple-low-battery-voltage.html
Aminu Yahaya Ibrahim says
Thanks very much Sir.
My next queations are on the charging circuit and the componets like diodes and relays currents.
Assume I want to use 200ah battery, what value of the diodes and relays is needed when the tranfo is 20A.
Also, I can see in most of the charging circuit, the charging resistors is 10watt bigger, so an I go ahead with it or it needs to be change to biggest like 15watts to above.
thank you Sir.
Swagatam says
Aminu, for 200 AH battery the diodes and relay contacts will need to be rated at 30 to 40amps
which charginh resistor are you referring to, please provide the link
Aminu Yahaya Ibrahim says
Good day Sir,
Sir based on this post, I have an Idea of using 7.2-0-7.2 transformer, removed from 350va ups. So if I use the outertap of tranfo i.e 7.2+7.2 It will give 14.4v which can charge 12v battery with bigger AH. But, I dont have any skill on how to buit it like the one on this post, and what charging circuit is suitable for the tranfo and the battery.
Always, your help is highly appreciated.
Thanks a lot.
Swagatam says
Good day Aminu,
For lead acid battery the recommended charging current should be 1/10th of its AH rating.
the type of charger will depend on your choice, it could be automatic, or manual as you prefer.
I have posted battery charger circuit designs, you can refer to those for more help
https://homemade-circuits.com/search/label/Battery%20Charger
Elanchezhian Ponnusamy says
Dear sir,
i want circuit design for flyback microinverter 230AC single phase
Swagatam says
Dear Elan, please provide more info regarding its specs…
ARAVINDH BALASUNDARAM says
Sir i am Prem. Sir can i connect a 12volt 2amps solar panel instead of a 12volt 10Ah battery.
Will it work…
Swagatam says
Aravindh, 2 amp is quite low, and will produce not more than 20 watts at the output.
Sribasu says
Hi Swagatam,
Thanks for this useful circuit. I have a 7Ah battery and a 12-0-12 4A Step Down transformer. I want to use the transformer in reverse, just like how you did. Could you please tell me what are the adjustments required in the circuit, in order to make it work with the above 2 parts?
And what will be the output power of this circuit? Is it 12×4=48 Watts or lesser?
Swagatam says
Hi Sribasu, you won't have to change anything, and may use the same design with your battery and the mentioned transformer.
However the transformer should be ideally 9-0-9V for a 12V battery, in order to be able to generate around 260V initially with a fully charged battery…
with a 12V trafo, the initial voltage could be around 220V and drop to 190V as the battery discharges.
the output max wattage will be 48 watt in ideal situations, and if your trafo is true 4 amps rated otherwise you shouldn't expect more than 30 watts from the system.
Sribasu says
Great! Thanks for the information.
andrei ruiz says
sir do u have circuit for 12v to 350v smps converter!??
Swagatam says
you can try the following concept with some modifications:
https://homemade-circuits.com/2013/03/how-to-convert-12v-dc-to-220v-ac-using.html
arun kp says
Thanks sir
arun kp says
sir
i want to run a cooling fan with intervals, for mosfet.
can you suggest such a circuit??
Swagatam says
arun, you can use an IC 555 astable circuit and connect a small PC fan directly across its pin3 and ground, and set the RC components for switching it with the required time delays
Aminu Yahaya Ibrahim says
Ok Sir,
Am happy to hear this Sir.
Again, It will be better if You could develop the one that can provide stable output voltage even with the 88% load.
Say, the invarter can produce 500 watts and the load is alteast 420 watts, while the output volt can not change from 220v.
My best regard Sir!
Swagatam says
Aminu, actually I already have the design posted in my blog, you can check it out here:
https://homemade-circuits.com/2012/02/how-to-build-simplest-modified-sine.html
Aminu Yahaya Ibrahim says
Sir I have gone through this blog throughly and I have some question as follows:
1. If we apply 2200uf/25 to above voltage, does this give us smooth power and prevent buzzzz sound from transfor?
as mentioned by the commenter Arun.
2. I heard u suggested the use of IC 555 to modify this circuit fron squear to sine wave. So, pin3 from ic555 is the output to the Gates of mosfets through 1N4148 diod, right? Sir is there no any other component to add here? Unlike in this post:
www.homemade-circuits.com/2013/04/how-to-modify-square-wave-inverter-into.html?m=1
3. How can I calculate the resistor's value if the caps is changed to above or below 2A474j cap?
Thank you very much Sir…
And I think this circuit mayb sinple for me than the one I mention in this comment, if it has no BC557/BC547 parts.
Swagatam says
Aminu, normally a high value capacitor is used across the battery terminals to cancel high frequency disturbances, so that helps to get a cleaner output
2) the T5/T6 circuit could be replaced with 555 circuit for achieving the same.
3) you may have to study transistor AMV formula for knowing this, it can be easily found online.
if pwm is used then you will need the 547/557 stage for preventing mosfet heating up
Aminu Yahaya Ibrahim says
Morning Sir,
This is Aminu again.
Sir, is there any possible modification on the above circuit to get modified sinewave output?
Or, any other simple and few components ciecuit available for modified sinewave?
Thanks for your kind and helpful work.
Swagatam says
Good morning Aminu,
you can add a 4017 IC in the middle of the T2 collector and mosfet stage…if possible I'll try to update the design soon.
arun kp says
Sir
I've modified the circuit board
and put a 2200uf 25V capacitor
across the supply.
Now is working perfectly…
No heat no hizzing sonud.
thank you so much
Swagatam says
That's amazing Arun, keep up the good work,
thanks for updating!!
arun kp says
you r right sir.
the legs of mosfet were short with its heat sink.i did'nt noticed it.
i'll try this until geting a good result.
arun kp says
Oh My goodness..
I set up the circuit and it worked for a few seconds and every components became tooooo hot. within 5 second The mosfet crashed and R3 broke .
All connenctions had burn away.
Sir
the components which I've used ,
R1,R2=140k
R3,R4=220ohm
C1,C2=2A104J
T2,T1=BC547
T3,T4=IRFZ44
Trans. 12-0-12 ,5 A
And a 12V 9Ah battery
Then…
what should I do sir??
Swagatam says
arun, everything cannot burn that's impossible unless something's severely wrong in your circuit connections.
change the 220 ohms with 1K, and I hope you have the mosfets mounted on good heatsinks, if not then put them on.
after this everything must run perfectly.
arun kp says
thank you sir
arun kp says
ma unfortune!
sir i did'nt get c1& c2( .47uf).
Is that proper with capacitor 2A104J & 140K instead of 27k?
is that a genuine idea?
plz rply me !
Swagatam says
yes, it's genuine and a standard principle.
arun kp says
first of all ,thank you for your valuable advice & direction.
sir
am going to fix 474J 63v cappacitor for C1&C2 .
is gonna make any problem?
Swagatam says
no problems, you can go ahead with it.
arun kp says
Sir
What should I do with the Earth indicated points on the above circuit???
Swagatam says
the earth is just the battery negative, nothing more.
arun kp says
sir
am Arun.
could you plz show me an image of 0.47uF/100V metallized capacitor?
I went to retailer and asked for 474J 100V capacitor,but he did'nt heard understand for what am asking for!
hope you may help me
Swagatam says
arun, you can use any standard ceramic 0.47uF capacitor, the given specification is not critical.
Swagatam says
you can use other values also for C1/C2 such as 0.1uF which is five times less than 047uF, but that would mean you will need to increase the 27k values five times more, that's equal to around 140K
arun kp says
Thank you so much sir
mayokun deji says
thanks alot for the reply.one more question,why is it that such transformer of the same wattage that i use powers the cpu and monitor in a ups and usaid mine even cnt power a 100watt bulb. secondly pls can u post the modified sine wave of the above circut.thanks again
Swagatam says
CPUs and monitors are designed to work with low voltages also, since these have SMPS which are assigned to work even at as low as 100V.
the modified design can be seen here:
https://homemade-circuits.com/2013/04/how-to-modify-square-wave-inverter-into.html
mayokun deji says
thanks for the help.really greatful.sori another question to go.pls if i want to upgrade to aroun 350watt of the aboove circuit what are the modifications to make.thanks again
Swagatam says
just upgrade the trafo, that's all
mayokun deji says
thank you alot greatful
mayokun deji says
hello sir.i have a problem with an inverter and would love u to help me out. i built a square wave inverter with ic cd4047 i use irf3205 fets at d output.i used four irf3205 two on each side.couldnt get a 12v-0-12v transformer so i used a 16v-0-16v transformer rated around 4amp i power d inverter with a 12v 75ah car battery.my problem now is am geting above 250v ac and anytime i connect a 60-100watt filament bulb it may not glow or when it glows it dim and the voltage drops to around 100v ac.pls help tanks
Swagatam says
Hello Mayokun,
first of all the transformer voltage should be always lower than the battery voltage…for a 12V, it could be around 9-0-9V, secondly a 4 amp trafo as in your case will be able to produce:
4 x 12 = 36 watt in most ideal conditions…so expecting a 100 watt is no good
use a 9-0-9 or a 12-0-12V trafo rated at at least 10 to 15 amps for illuminating a 100 watt brightly
NILESH GANVIR says
Plz send me
Pure sinewave inverter design for grid synchronization for home inverter with 500watt
Purna says
Hi sir, I want to ask you a question regarding the IC CD4047. My question is that, what number of mosfets can the IC Cd4047 drive? i.e. What is the maximum output power(WATTS) I can get if I use Cd4047 inverter circuit? Waiting for your reply sir.
Swagatam says
Hi Purna, you can use any desired number of mosfets with this IC or any similar IC and get any desired power output from the inverter transformer.
the transformer and the battery decide the power (wattage), not the IC, the IC is only for the initiating the mosfets as per the set frequency.
Purna says
Thanks for the help sir. Can you please suggest an IC number as I want to build a circuit that can drive loads upto 1000watt. I am going to use IRF 3205 mosfets.
Swagatam says
4047 IC is the ideal IC to start with, other ICs are relatively complex to configure
Purna says
Thank you very much for your help sir.
fasat2112 says
Hello,
Is it requred to use 12-0-12v transformer or it could be with only two wires?
And also why is used 3 wires primar?
Thank you in advance.
BR
Swagatam says
Hi, yes a center tap trafo is necessary here since the circuit uses a push pull type of topology, two wire trafo will not work here.
the primary center tap is used to connect with the battery
for a 12V batt the trafo primary must be rated at 9-0-9V, that is, slightly lower than the battery voltage
prateek goel says
hi sir i am a new comer here i want to know that r1 r2 has 27 kohm values each?
also for r3 r4 r5 r6?
ur respnse will be highly appreciated.
thank you
Swagatam says
Hi Prateek, it's given in the parts list below the diagram, yes R1/R2 = 27K ohms
rest are 470 ohms
samar tauheed says
Hi! This is samar i want to ask you about this circuit that can i use mylar or electrolyrtic capacitor instead of metallized and the second thing is that can i take 30 watts load from 12-0-12, 3amp transformer rating. thanks in advance. waiting for your kind reply.
Swagatam says
Hi, yes mylar or electrolytic caps can be used, if the trafo is truly rated at 3 amps then 30 amps can be expected from it.
samar tauheed says
Hello! i want to ask you about a inverter circuit i made an inverter
circuit by follow this circuit diagram but when i connected 12-0-12, 1
ampere transformer it cant converting to 220volt and transformer is
heated can plz tell me about the problem and i got 12,12 volt from
mosfet transitor can you plz explain?
Swagatam says
hello if your transformer is getting hot, it means either the transformer is faulty or the inverter is not oscillating.
First make sure the junction of R4/R5 is generating the required 50 Hz frequency, confirm this by keeping the transformer disconnected…
if this is OK, it would indicate a possible fault in the transformer
anas kalla says
hi sir. Shall i use npn transistor (2n3904) in oscillation stage with reverse polarity.
Swagatam says
you can use it in the correct polarity, matching with the shown BC547 poarity
shadab karnachi says
hi swagatam,
Well i stated you that i am making an inverter.
my actual goal of making an inverter, which can actually able to power big devices like tv or computer of 300 watts from low power consuming devices like 12 volt adapters. i know is bit of impossible idea?
but i thought that first we need to connect an 14 volt strictly regulated current and voltage adapter to the mains. And we will connect the output to the battery of 12 volt for charging and after charging we will take up an 800VA inverter and connect it to the battery, leaving the mains adapter switched on as it is. Simultaneously we will switch the inverter on and give out the load. it will usually draws current from adapter only. but if the load increases, the battery act as an supplier. as i stated that battery should be charged first and then should be connected to the inverter. and this is something adding a wire in between the mains and the load. can you tell me if there is any possibility of this design?
I read an common inverter design, there is always a backup like system where mains are either connected directly to the load or they are backed up by an battery if there is mains failure.
can we also replace battery with ultra or super caps following my design?
please please reply.
advance thankx
Swagatam says
Hi Shadab,
What you are assuming is incorrect and therefore will not work, 300 watts means 300/12 = 25amps, you will need an adapter capable of providing 25amps for relieving the battery from the load…..
achilles hector says
thanks for the answer!!!
what modifications will I make to obtain 200 watt ?
500 watts ?
sine wave?
Swagatam says
the above circuit will give 200watt easily, for sine wave again you will have to employ a 555 IC and diode network at the gates of the mosfets.
network advise says
hi sir
this srinivas
ihave a doubt can i use irf3205 mosfet with circuit and ihave a 600 va computer ups transformer is 12-0-12
please suggest me
thank & regards
Swagatam says
Hi Srinivas,
Yes you can use the mosfet with the mentioned transformer.
saravana says
i desing the ckt but its not working….. wht i do sir…….????
Anonymous says
Hello Sir,
My circuit is working again.One question, do I need to attach Heat Sink with mosfets and if yes then how large it should be??
Thanks
Sadi
Swagatam says
Hello Sadi,
Yes heatsink is necessary if the devices are getting hot, use a size which keeps the mosfets reasonably cool.
Anonymous says
Hello Sir,
in the circuit, the biasing voltage is negative on both transistors.I replaced the transistors and capacitors but still getting negative bias voltage across base to emitter.
I am completely confused whats happening, please help
Thanks
Sadi
Swagatam says
Helo Sadi,
I am not able to identify any potential threat that might be causing damage to the mosfets, however during transition periods there may be a chance of the mosfets conducting simultaneously for a split second, although quite unlikely it's better to tackle it also.
put zener diodes in series with the emitters of the BC547 transistors, anode to ground and cathode to emitter. zener value can be anything between 3 and 9v.
Don't worry about the transistor biasing voltage because here it would be continuously changing from positive to negative vice versa due to the oscillating nature of the circuit…..assuming that you have built the AMV correctly.
Anonymous says
Hello Sir,
My circuit crashed again :(. I can not find out the problem.
Please Help!!!
Sadi
Anonymous says
Hello Sir,
I designed this circuit for PCB. Will it work in PCB diagram properly or do you have any suggestion??
Thanks
Sadi
Swagatam says
If your PCB layout is correct as per the diagram then it would definitely work
Anonymous says
Hell Sir,
Good news, After replacing Mosfets its working again.Thanks. I also used diode across drain to source that you updated.Well,I couldn't find 1n5402 but I found 1n5408.So I used that,will it be useful?? I lighted up a 25watt bulb and its working fine but the frequency is 105Hz.If I use only bulb in this circuit do I need to adjust the frequency or It will work??
Thanks for your help.
Please reply
Regards
Sadi
Swagatam says
Hello Sadi,
That's great news.
For resistive loads such as bulbs, the frequency isn't important, even for CFLs this won't be a problem.
Anonymous says
Hello Sir,
all right,I will try with new mosfets and diodes but for your concern I used IRF540N mosfets and they have built in zener diodes across Drain to Source.You can see the datasheet.One more thing will get 50 Hz from this circuit because when I measured the frequency I found 120 Hz although the circuit was malfunctioning then.
Thanks
Sadi
Swagatam says
Yes Sadi, I know that but since I am not able to figure out any other potential issue in the design,so I am assuming it to be the possible cause of your mosfet damage.
Also connect 1K resistors across collector/emitter of T1/T2, that might help control transients.
Anonymous says
Hello Sir,
with great regret I nee to inform you that my inverter is not working correctly now.it was okay till yesterday.I checked it with square to sine wave inverter circuit.But today when I checked again it was not working.Then I removed the sine wave converter circuit and tried again.But its still dead.I was gettin only 36v to 238 mv.one of the mosfets is getting more hot than another.What shall I do now?? I need to build this project very soon.Please help
thanks
Sadi
Swagatam says
Hello Sadi,
I think the mosfets might have got damaged due to the absence of flyback diodes across D and S of the mosfets, I'll update the diagram, please add it in your circuit accordingly.
Anonymous says
Yes, I have done it.
The circuit is completed and its working great.
Now I want to make the square wave into sine wave. I read it in your blog.will it work???
Thanks a lot Sir.
Sadi
Swagatam says
That's cool Sadi,
Yes it will work, please refer to this post:
https://homemade-circuits.com/2013/04/how-to-modify-square-wave-inverter-into.html
Anonymous says
Hello Sir, I attached a transformer of 12v 1amp from which i got the required output 220v ac but the current is very low like 0.05 ampere.I suppose I need to add a step up transformer here. What do you suggest???
Thanks
Sadi
Swagatam says
use a 12V/5amp transformer and a 12V 10AH battery for getting higher current outputs
Anonymous says
Hello Sir,
I couldn't find a 9-0-9v 5amp transformer at the closest market. I have a battery that is rated with 12v 7AH.Can I use a 12-0-12v 5amp transformer in this circuit?? If not, what do you suggest??
Is there any difference if i use step down tranformer reversly instead of a step up transformer?? Please Help me.I have bought IRF540n mosfets,will they work in this circuit??
Thanks
Sadi
Swagatam says
Hi Sadi,
You can use 12-0-12V trafo, but you will need a fully charged battery upto 14V for acquiring the required 230V output from it.
Anonymous says
Hello Sir,
I need a lead acid 12v 7Ah battery charger also,do you have it??
it would be a great help.Thanks
Sadi
Swagatam says
Hello Sadi,
Just type "smart automatic charger" in the above search box, you will find your circuit there.
Anonymous says
Hello Sir Swagatam,
Can i simulate the inverter circuit using Multisim or Proteus? because i can't find the suitable transformer for the simulation.
Swagatam says
yes you can do it.
Swagatam says
you can try any closely rated trafo…
Anonymous says
Hello Sir Swagatam,
regarding on upgrading it with more mosfets for getting more power, may i know how the mosfets should be connected in order to increase the power? for example, how to connect more mosfets because mosfets have drain, gate and source. sorry because i totally dont have idea about it.
by the way, both mosfets are N-channel mosfets right?
greatly appreciate for your help.
thank you
Swagatam says
You can added more number of mosfets by directly connecting their gates, drains and sources parallel with the existing mosfets, just make sure that each mosfet has it's own separate resistors similar to R5/R6, drains and sources can be directly joined in parallel…the resistor ends can be joined with transistor collectors as done with the existing mosfets.
All mosfet numbers should be exactly identical
shaik mohammed Yaseen says
hi sir!
i'm yaseen
i have done all the connections of this circuit but i couldn't know how to check this circuit.
so,please help me about the process of checking this circuit
Swagatam says
Hi Yaseen,
connect an automobile battery to the shown points and a load (220V bulb) at the transformer output, and switch ON the battery power, the bulb will illuminate with full brightness.
you can check out the videos.
pp says
Hi..Finally preparing to make this circuit..but still I want some advance features in this…If you can help me out with it…
1> Battary Over-charging protection
2> Day time Sensor
3> Auto shut on AC Mains On
Swagatam says
Hi PP,
I have already explained all these circuits separately in this blog.
1)battery overcharge circuits are their in plenty in this blog,
2) day time sensor circuits are alos there in this blog,
3)relay change over circuits are also covered in this bog.
pp says
Sir,
Actually this is the time to Upgrade this particular circuit with above mention features to make it NEW and secondly, searching for this features individually on the blog is wastage of time, if found, the connections should be logically correct and this is very time consuming…what do you say ???
Regards,
Swagatam says
Hi Girish,
The rms value is correctly matched with a sine rms in modified sine wave inverters, but not in square wave models
Anonymous says
Hi sir. may be you are right, the transformer has no brand name and it did't weight 4-5Kg.
but i can't say that 7Ah battery has no enough power to light 60 W bulb , because an average computer UPS is powered by 7Ah battery to produce 360 W maximum for 15 minutes .
can you tell me how a modified sine wave inverter is better than a square wave inverter.
thank you for your kindly reply – Girish
Anonymous says
HI SIR.
This is Girish. i tried your circuit. it works well.i connected 12-012v/5a transformer and MOSFET is IRF540N battery is 12v 7Ah, the output voltage was around 210V . but i found problem with 60w incandescent bulb. it was dim. i know that 5A transformer gives less than 60 W, When i done the experiment on table it seemed to be bright. but when it is connected to wall bulb holder directly from inverter. it was dim, not because of that it the holder had any loose connection.when i connect the bulb to direct to AC mains it was brighter.then i think it is due to low RMS value output because it is square wave. it gave good result with tube light 40W (with electronic choke). do you think that it is due to low RMS.
Swagatam says
Hi Girish,
it's not due to low rms.
your transformer may be labeled as 5amps but actually it may be rated just at 3 amps.
a correct 5amp transformer should weigh around 4 to 5 kgs.
also a 7ah battery won't produce enough power, you will have to use at least a 25ah battery
Anonymous says
sir can iuse irf3205 and teansformer form ups to make 600va inverter with this circuit???
Swagatam says
you can an inverter, not an UPS
Muhammad Awais says
Hi.
Q: What should be the o/p voltage at drain of Mosfets before connecting transformer?
I used a stimulation based software that gave me the square wave providing only 1v.
Swagatam says
It would be around 1/2 the supply voltage, for 12V supply it would be around 6V.
pp says
Hi..
Regarding Transformer, I have Stepdown 12-0-12 5Amp..can it be used reversed as a inverter with above given Schematic???
Swagatam says
yes it can be used.
Bibin Edmond says
Hi Swagatam,
i assembled this circuit on a breadboard, while using this inverter for lighting a cfl, those two mosfets are getting hot. is that normal ? do we have to use a heatsink…?
Swagatam says
Hi Bibin,
without a heatsink, the mosfets will get a bit hot, it's normal…. but if is getting too hot very quickly then it may not be normal.
Anonymous says
Hi, i want to ask you if this inverter can work well with 12V 5AH battery?
Swagatam says
yes it will work with 12V 5ah battery.
Anonymous says
Hi, I want to ask you if this inverter can be used as a sine wave bcz in my project i have to make an inverter which can supply the cell phone charger and lamps?
Swagatam says
Hi, the above circuit is not a sine wave design, but it can be used for powering a cell phone charger, and even lamps.
sunil solanki says
Sir,
i want to know that, the load capacity of inverte depend on which component in inverter circuit. Please tell me.
Swagatam says
transformer rating, mosfet rating and battery rating
Abhishek Sharma says
Hi sir, as sunil solanki asked " solankiApril 18, 2013 at 11:32 AM
Sir,
i want to know that, the load capacity of inverte depend on which component in inverter circuit. Please tell" and you answered " transformer rating, mosfet rating and battery rating" so I want to ask that what about the transistors used in oscillator circuit? Will they remain same and in good condition on applying a tubular battery like mains inverter used for home ? And if I am not using safety dioddes
Swagatam says
Hi Abhishek, the oscillator is only for generating the frequency, it has no role in the power delivery of the inverter, neither will it get affected by the battery type or its current as long as its operating voltage is not exceeded
only the transformer and the battery determine for the actual power output capacity…the fets must be rated to handle this power so that they don't burn out
Abhishek Sharma says
Sir, can you please tell me that how many watts the circuit can deliver if I use mosfet 3205 and a 12-0-12 5amp transformer and I am using a 12v 7.6ah battery.2 And how much watts will be delivered if I use mosfet irfz44n with the same battery and transformer. I am not using any diodes in my circuit. The circuit can deliver 40watts. If I am using irf 540n
Swagatam says
12 x 5 = 60 watt in ideal condition, but practically it could be only 40 watts
Kannan says
Hi, I am beginner to circuits and want to give a first try with your circuits!!
Shall i use Transformer = 9-0-9V, 5 amp, and Battery = 12V,12AH?
Swagatam says
Hi, yes you may proceed with the project.
Swagatam says
it's not a useful circuit….
edalcor zuproc says
hi good day! can i use tantalum capacitor in this circuit?
Swagatam says
good day! yes you may use them, but be sure with the polarity, (+) goes to the bases….
edalcor zuproc says
ok thanks i will try
saravanan .n says
Hi,i am saravanan, 1. in this commet list, one of the member asked,it will run a celeaing fan in this circuit! For that question, you says, if you use 20ah battery and 10amp trasformer, you can run it,to said them. You are says that the squar wave inverter is not to use the tv,fan ect. Than how can you says that 2.if i use 3 15w cfl,s in that 50w inverter THANK YOU
Swagatam says
ideally a square wave it's not good for inductive loads but it won't do any harm to a fan so it can be operated….
Akshay says
what will be the rating of the components for a rating of 500watts?
will there be any major change in the circuit.?
can u provide me with the circuit diagram for this rating..
Swagatam says
just use a transformer rated at 24-0-24V/20 amps, and use a battery rated at 24V 200 ah.
It should do the job, rest everything will remain as shown.
saravanan .n says
Hi, i am saravanan i have ask some qustions to you 1. In the circuit, i use 10amp transformer how many watts i will got? 2.in this circuit i sall use the above 20ah battery 3.can i lightup 3 14w cfl in this circuit 4.if i use 3 cfl means how many hourse the battery will backup 5.9v 5a transformer,how many rupees 6.it the transformer makes much noise 7.i want squar wave to sine wave converter circuit please post it Thank you
Swagatam says
1. 100 watts
2. 20ah batt will do.
3.3 14watt cfl is ok
4. back up time not sure.
5. Rs. don't know.
6. No
7. I will try.
thanks
abdul jaffer says
can i use 9v 500 micro amps transformer instead of 8amps transformer
Swagatam says
No…
vinod vaikom says
Mr. Abdul Jaffer, the output power of an inverter depends upon the transformer. Multiply transformer voltage and amperage. In your case 9*0.5 =4.5w. Do you think you can light up a 11w CFL with this transformer ?…
Dheeraj More says
What are the values of C1 and C2
Swagatam says
see parts list.
Anonymous says
Hi sir. Have you designed such type of circuit using phototransistor? I have done hundreds of tries but i failed…. Can you give me a circuit or a refering website . -girish.
Anonymous says
Hi sir . I am girish. I am here not about this inverter. I have a phototransistor and a IR LED . I want to glow a red LED using phototransistor when IR LED is on (directed towards phototransistor). Can you suggest me a idea or give me a refering website.
Swagatam says
Hi Girish,
that would not be feasible without an external power supply attached, the phototransistor output will need to be amplified through another stage comprising an external transistor driver stage for illuminating an LED.
Anonymous says
Hi sir. There will be hum noise in audio units if i connect the inverter. Like vcd and dvd.???
Can this inverter run 14 inch 60w colour tv.?
Swagatam says
No this inverter is for resistive loads only…
Anonymous says
In thir circuit you have used 9-0-9v transformer but batery is of 12v. How will it run? It should be 9v batery for this transformer or for 12v batery d xmer should b 12-0-12 v.
Swagatam says
to sustain higher output voltages even when the battery voltage drops below 12 or 11 volts.
Anonymous says
i mean to say batery voltage and xmer prim voltage should be same.
4 dis case xmer should b 12-0-12 volts.
Swagatam says
transformer voltage should be a little lower than the battery voltage.
Anonymous says
Thanks 4 sugestion. I will implement in my circuits.
Anonymous says
Hi sir. I am getting noise from the transformer.My transformeris 12volt and 3amps.I get maximum noise when i connect load between 15 to 25watts.when no load is connected still noise exist.
Swagatam says
Your transformer may be faulty, because I did not face this issue in my circuit.
Bibin Edmond says
Hi swagatam,
Can we use two 6v 5ah battery instead of 12v battery.. ?
Swagatam says
Hi Bibin,
yes Put them in series….
Bibin Edmond says
ok…. ! thanks swagatam….!
Bibin Edmond says
Hi swagatam,
can we recharge the serial connected batteries together using 12v battery charger circuit or it should be done separatedly with 6v battery charger circuits.. ?
Swagatam says
Hi Bibin,
It is not recommended, but it can be done because nothing is critical about it.
Preferably you should charge them separately using a 6V charger.
Anonymous says
Hai Swagatam dis is Narendra..
We are doing a Mini project on Inverter without MC's.. Can u please mail me da details and description abt Inverter without MC's..
My email id:: yuva.narendra@ymail.com
Thank you 🙂
Swagatam says
Hi Narendra,
I have discussed plenty of simple inverter circuits in this blog, you may select any of them appropriately as per your needs, every circuit has been explained elaborately.
Regards.
Anonymous says
With 20 Ah battery how many hours the celling fan run????
Swagatam says
Assuming the ceiling fan to be 60 watts, it will run for about 2 to 3 hours max.
Anonymous says
It will run a celling fan?
Swagatam says
If you use a 9-0-9/10amp trafo, and a 12V/20AH batt then you can run a fan with the above inverter.
Anonymous says
how did you calculate that it is a 50 watt inverter and can i use a 6 volt battery as i am not having the 12 volt battery.
Swagatam says
50 watt is according to the transformer rating.
6 volt will give 50% less power than the given specs.
Anonymous says
which two n channel mosfets did you use please give me the names.
Swagatam says
SK1058
Anonymous says
will this circuit work for my 18 watt cfl bulb.
Swagatam says
yes, will work
Anonymous says
Dear sir , i need a simplest sine wave inverter. Please give the web site.
Swagatam says
You can try this circuit:
https://homemade-circuits.com/2012/05/make-this-1kva-1000-watts-pure-sine.html
Anonymous says
can i use phase shift oscillator for sine wave -means to get sine wave output from the transformer . If i use phase shift oscillator in place of multivibrator (the oscillator) , it will work?
Swagatam says
Yes you can use it, but you cannot just connect it with transistors, mosfets and transformers for making a sine wave inverter.
Swagatam says
no it will not work in place of an AMV in a square wave inverter
Anonymous says
Hi sir. Shall i use phase shift oscillator for sine wave.
Swagatam says
Your question is unclear…
Anonymous says
hi sir. Shall i use pnp transistor (BC558) in oscillation stage with reverse polarity.
Swagatam says
yes it will work if the all the relevant polarities are reversed.
Anonymous says
Hello sir. Is there is a method to convert square wave into sine wave? And modifide sine wave inverter is safer than square inverter?
Swagatam says
You can use a PWM processor for converting a square wave to modified sine wave equivalent….refer this article to understand more:
https://homemade-circuits.com/2012/12/how-to-use-ic-555-for-generating-pwm.html
Anonymous says
hi sir. With 3A transformer i glowed 36watt tubelight philiphs flick free technology ,but the transformer getting tooooooo hot, even i cannot touch the transformer for a second. I am worried that the insulation of transformer coil get melted and make shot circuit . Shall i change the transformer to 5A with same load. Is this reduce the heat?
Swagatam says
Anything that's getting toooooooooo hot should be immediately removed and replaced with a powerful one 🙂
Actually I have no idea how and what you are connecting, so I cannot suggest anything, if possible tell me about the whole configuration then may be I would be able to help you out….
Anonymous says
hello sir. Are you sure that this gives 50watts output because transformer value 12v*3A it gives 36watts
Swagatam says
It should be 5 amps, or possibly more than that. I'll make the correction.
Swagatam says
Hi Vinod,
Yes you can use it.
Vinod KC says
Hi Swagat,
Can i use 63v box type polyester film or ceramic capacitor instead of metalized ?
Vinod KC says
Hi swagat,
I built an inverter with CD4047, IRF540 and 12-0-12 10A transformer. But the out put voltage is 208 VAC. Hoe to increase it to 230 VAC ?.
Swagatam says
Hi Vinod,
Use 9-0-9v transformer, the voltage will boost up to 250V…..
Vinod KC says
Hi swagat,
Thank you. Let me try.
Swagatam says
Nothing will happen, they are not required actually…. you may take them of…..
MWANZIA KIOKO says
Hi sir,am so grateful that my oscillator is perfectly working.since my multimeter isn't showing any readings wen am testing mosfets in diode mode,how else should i identify its leads??(IRF 740)
MWANZIA KIOKO says
Hi sir,will it be correct if i use mosfets in the oscillator circuit in my 50 watt inverter?
Swagatam says
Why mosfets??? transistors are far too cheap and perfectly suited….and anyway mosfets might not work properly in the oscillator stage.
Mwanzia says
Thankyou very much for your kind assistance,scientific father!!! Good day
Swagatam says
You are welcome son!!:)
MWANZIA KIOKO says
Hi swagatam,how is you?in your 50watts,can SD 8050 transistors + mosfets be used to produce a 50Hz (220Vac)?thanks in advance
Swagatam says
Hi Mwanzia,
Yes it can be used, in fact any similar NPN transistor can be used.
sultan says
is this a pure sine wave inverter
Swagatam says
No, it's a square wave design…
Swagatam says
Hi Rashid,
I have updated the parts list, please check it….
Rashid Ansari says
Hello Sir,
Greetings
What are the values of C1 and C2.
Thanks.
Best Regards
Anonymous says
Hello,
it says in the parts list that C1 and C2 are identical capacitors with a total capacitance of 0.47 mircofarads (470 nanofarads) and a voltage rating of 100V. Please read the text carefully before asking questions.
Cheers!