5kva Ferrite Core Inverter - Full Working Diagram with CalculationDetails

In this post we discuss the construction of a 5000 watt inverter circuit which incorporates a ferrite core transformer and therefore is hugely compact than the conventional iron core counterparts.

Written and Submitted By: Dhrubajyoti Biswas

DC Input Supply Prerequisite

First you need to find 60V DC power supply for powering the proposed 5kVA inverter circuit. The intention is to design a switching inverter which will enable change the DC voltage of 60V to a higher 220V at a lowered current.

The topology followed in this scenario is the push-pull topology which uses transformer on the ratio of 5:18. For voltage regulation which you may need, and the current limit – they are all powered by an input voltage source. Also at the same rate, the inverter expedites the current allowed.

When it comes to an input source of 20A it is possible to get 2 – 5A. However, the peak output voltage of this 5kva inverter is around 220V.

Ferrite Transformer and Mosfet Specifications

In regard to the architecture, Tr1 transformer has 5+5 primary turns and 18 for secondary. For switching, it is possible to use 4+4 MOSFET (IXFH50N20 type (50A, 200V, 45mR, Cg = 4400pF). You are also free to use MOSFET of any voltage with Uds 200V (150V) along with least conductive resistance. The gate resistance used and its efficiency in speed and capacity must be excellent.

The Tr1 ferrite section is constructed around 15x15 mm ferrite c. The L1 inductor is designed using five iron powder rings that may be wound as wires. For inductor core and other associated parts, you can always get it from old inverters (56v/5V) and within their snubber stages.

Using a Full Bridge IC

For integrated circuit the IC IR2153 can be deployed. The outputs of the ICs could be seen buffered with BJT stages. Moreover, due to the large gate capacitance involved it is important to use the buffers in the form of power amplifier complementary pairs, a couple of of BD139 and BD140 NPN / PNP transistors do the job well.

Alternate IC can be SG3525

You may also try to use other control circuits like SG3525. Also, you can alter the voltage of the input and work in direct connection with the mains for testing purpose.

The topology used in this circuit has the facility of galvanic isolation and operating frequency is around 40 kHz. In case if you have planned to use the inverter for a small operation, you don’t cooling, but for longer operation be sure to add a cooling agent using fans or large heatsinks. Most of the power is lost at the output diodes and the Schottky voltage goes low around 0.5V.

The input 60V could be acquired by putting 5 nos of 12Vbatteries in series, the AH rating of each battery must be rated at 100 AH

High Frequency 330V Stage

The 220V obtained at the output of TR1 in the above 5kav inverter circuit still cannot be used for operating normal appliances since the AC content would be oscillating at the input 40kHz frequency.For converting the above 40 kHz 220V AC into 220V 50 Hz or a 120V 60Hz AC, further stages would be required as stated below:

First the 220V 40kHz will need to be rectified/filtered through a bridge rectifier made up of fast recovery diodes rated at around 25 amps 300V and 10uF/400V capacitors.

Converting 330V DC into 50 Hz 220V AC

Next, this rectified voltage which would now mount up to around 310V would need to be pulsed at the required 50 or 60 Hz through another full bridge inverter circuit as shown below:

Update: An upgraded version of the above can be studied in this PWM sinewave 5kva inverter circuit

The terminals marked "load" could be now directly used as the final output for operating the desired load.

Here the mosfets could be IRF840 or any equivalent type will do.

How to Wind the Ferrite Transformer TR1

The transformer TR1 is the main device which is responsible for stepping up the voltage to 220V at 5kva, being ferrite cored based it's constructed over a couple of ferrite EE cores as detailed below:

Since the power involved is massive at around 5kvs, the E cores needs to be formidable in size, an E80 type ferrite E-core could be tried.

Remember you may have to incorporate more than 1 E core, may be 2 or 3 E-cores together, placed side by side for accomplishing the massive 5KVA power output from the assembly.

Use the largest one that may be available and wind the 5+5 turns using 10 numbers of 20 SWG super enameled copper wire, in parallel.

After 5 turns, stop the primary winding insulate the layer with an insulating tape and begin the secondary 18 turns over this 5 primary turns. Use 5 strands of 25 SWG super enameled copper in parallel for winding the secondary turns.

Once the 18 turns are complete, terminate it across the output leads of the bobbin, insulate with tape and wind the remaining 5 primary turns over it to complete the ferrite cored TR1 construction. Don't forget to join the end of the first 5 turns with the start of the top 5 turn primary winding.

E-Core Assembly Method

The following diagram gives an idea regarding how more than 1 E-core may be used for implementing the above discussed 5 KVA ferrite inverter transformer design:

E80 Ferrite core

Feedback from Mr. Sherwin Baptista

Dear All,

In the above project for the transformer, i did not use any spacers between the core pieces, the circuit worked well with the trafo cool while in operation. I always preferred an EI core.

I always rewound the trafos as per my calculated data and then used them.

All the more the trafo being an EI core, separating the ferrite pieces were rather easy than doing away with an EE core.

I also tried opening EE core trafos but alas; i ended up breaking the core while separating it.

I never could open an EE core without breaking the core.

As per my findings, few things i would say in conclusion:

---Those power supplies with non-gaped core trafos worked best. (i am describing the trafo from an old atx pc power supply since i used those only. The pc power supplies do not fail that easily unless its a blown capacitor or something else.)---

---Those supplies that had trafos with thin spacers often were discolored and failed quiet early.(This i got to know by experience since till date i bought many second hand power supplies just to study them)---

---The much cheaper power supplies with brands like; CC 12v 5a, 12v 3a ACC12v 3a RPQ 12v 5a all

such types ferrite trafos had thicker paper pieces between the cores and all failed poorly!!!---

In FINAL the EI35 core trafo worked the best(without keeping air gap) in the above project.

5kva ferrite core inverter circuit preparation details:

Part 1:

Using 5 Sealed Lead Acid batteries of 12v 10Ah

Total voltage = 60v Actual voltage

= 66v fullcharge(13.2v each batt)voltage

= 69v Trickle level charge voltage.

Part 2:

After calculation of battery voltage we have 66volts at 10 amps when full charged.

Next comes the supply power to ic2153.

The 2153 has a maximum of 15.6v ZENER clamp betwen Vcc and Gnd.

So we use the famous LM317 to supply 13v regulated power to the ic.

Part 3:

The lm317 regulator has the following packages;

1. LM317LZ --- 1.2-37v 100ma to-92

2. LM317T --- 1.2-37v 1.5amp to-218

3. LM317AHV --- 1.2-57v 1.5amp to-220

We use the lm317ahv in which 'A' is the suffix code and 'HV' is the high volt package,

since the above regulator ic can support input voltage of upto 60v and output votage of 57 volts.

Part 4:

We cannot supply the 66v directly to the lm317ahv package sice its input is maximum of 60v.

So we employ DIODES to drop the battery voltage to a safe voltage to power the regulator.

We need to drop about 10v safely from the maximum input of the regulator which is 60v.

Therefore, 60v-10v=50v

Now the safe maximum input to the regulator from the diodes should be 50 volts.

Part 5:

We use the regular 1n4007 diode to drop the battery voltage to 50v,

Since being a silicon diode the voltage drop of each is about 0.7 volts.

Now we calculate the required number of diodes we need which would buck the battery voltage to 50 volts.

battery voltage = 66v

calc.max input voltage to regulator chip = 50v

So, 66-50=16v

Now, 0.7 * ? = 16v

We divide 16 by 0.7 which is 22.8 i.e., 23.

So we need to incorporate about 23 diodes since the total drop from these amounts to 16.1v

Now, the calculated safe input voltage to the regulator is 66v - 16.1v which is 49.9v appxm. 50v

Part 6:

We supply the 50v to the regulator chip and adjust the output to 13v.

For more protection, we use ferrite beads to cancel out any unwanted noise on the output voltage.

The regulator should be mounted on an appopriate sized heatsink in order to keep it cool.

The tantalum capacitor connected to the 2153 is an important capacitor that makes sure ic gets a smooth dc from the regulator.

Its value can be reduced from 47uf to 1uf 25v safely.

Part 7:

Rest of the circuit gets 66volts and the high current carrying points in the circuit should be wired with heavy guage wires.

For the transformer its primary should be 5+5 turns and secondary 20 turns.

The frequency of the 2153 should be set at 60KHz.

Part 8:

The High frequency ac to low frequency ac converter circuit using the irs2453d chip should be wired appropriately as shown in the diagram.

Finally completed,


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tonisage said…
Pls.... is dis circuit tested and trusted. Has Dhrubajyoti Biswas
Already tested it to work? Thanks
Swagatam said…
yes it is a tested design, but the ferrite transformer will need to be designed correctly.

Alternatively a 5kva iron core transformer could be used with primary 50-0-50/100amps and secondary 220V or 120V
tonisage said…
Ok... But please am really interested in the ferrite transformer design because of its efficiency and light weight.
Swagatam said…
you can try it as per the given instructions.
tonisage said…
But d concept is different, in d link homemadecircuitsandschematics.blogspot.com/2012/09/making-200-watt-compact-pwm-inverter.html?m=1 high and low frequencies were used, but d configuration in dis 5kva transformer is just like a normal iron core Transformer(no high frequency).
Swagatam said…
please check the article, now it includes the low frequency stage also....
Good day Sir.
Is it possible for me to have a detailed list of materials for the inverter.
Thanks and best regards.
Swagatam said…
Good day Radley,

Please click the diagram to enlarge it, all the numbers are appropriately labelled beside the individual parts, you can easily note it from there.
Good day Sir.
I would like to ask your help again if this circuit is applicable also to 24V input voltage. cause i already have a 24V/220V transformer.
Thanks and best regards,
Swagatam said…
Good day Radley,

yes a 24V transformer/battery could be used in the above design, but make sure the IC gets a 12V regulated supply only
Good day Sir.
Is it possible to connect the IC to the battery which is 12 Vdc. Since, I'll be using 4 pcs of 12V. 2pcs connected in series and then connected in parallel with the other 2.
Thanks and best regards,
Hello again Sir,
My transformer is 24V-0V. without center tap.
is it still possible for me to use the above circuit.
Thanks and best regards,
Good day Sir,
Do you other design about a 5kva inverter that has a transformer without center tap.
Thanks and best regards,
Swagatam said…
Good day Radley, yes that would do, but use the battery which has its negative connected with the circuit negative.
Swagatam said…
You can try the second circuit separately for your application. Ignore the first circuit.

Connect the mosfet common drains/sources with +/-24V, and connect the transformer primary across the points shown as "load"
Good day to you Sir Swagatam,
Would like to ask you about the symbol load in the diagram.
Does it mean the consumer side already?
Thanks and best regrads,
Swagatam said…
Good day Radley, load indicates the appliance you would be interested to operate from the inverter....it's the final output from the inverter which could be used for operating the intended gadgets and appliances.
Good day Sir Swagatam. Hope you're feeling great today. could i ask you for some expert's advice? Which is better to use a Pure sine wave or the pulse width modulation invereter? And also, do you a PWM design which has a capacity of 5kva?
Thanks and best regards,
Swagatam said…
Hi Radley, both the counterparts are good, but PWM based are cheaper and more efficient.

Presently I do not have a 5kva PwM based design, if I find one will let you know.
Dear Sir Swagatam,
Thank you very much for the information.
More power to you and may you always be in good health.
Best regards,
Swagatam said…
Thanks Radley! It's my pleasure!
Good day Sir, what about the construction of the charging section in the circuit diagram?
Swagatam said…
Good day Muhammed, I have many battery charger circuit posted in this blog, any one of them can be suitably used with the above circuit for the required operations.
daniel adusei said…
hi sir it been a while thank for the good circuit im interesting in this circuit but there is one thing do not understand and it will be difficult to get it,the two circuit should connect together or it separate? can you please give me any equivalent type of the ic irs2453? or can i replace it with sg3525,TL494?
Swagatam said…
hi daniel, IRS2453 is a specially designed high side H-bridge driver IC, it cannot be replaced with 3535 or 494 ICs...it can be replaced with another full bridge high side driver only
Swagatam said…
the output voltage from the first circuit becomes the supply voltage for the H-bridge of the second circuit
daniel adusei said…
ok sir,please sir in the first circuit there is diodes can you please tell me any common diode can 1n4148 or any value of zinner diodes? these are the diods MUR415,DSEM2-06.any replacement of it?
Swagatam said…
please Google and find the datasheets of the indicated diodes...then check at what voltage and current these are specified...once you know this you would be able to identify and determine a suitable equivalent for the same.....1N4148 will not do.
daniel adusei said…
ok sir thank you ,has this circuit tested?

sir this circuit need another 60v dc? sir please can i ir2110 in place of the two ics? thank you
Swagatam said…
Not yet tested but I am sure the design is 100% correct technically and will work if built correctly...
yes ir2110 will do..
daniel said…
ok sir i want to ask you again if yes if2110 can replace the two circuit wha t can i do or nothing will going to change? 2110 and irs2453 and ir2153 are they the same pins?
Swagatam said…
please check the datasheet of the IC, yes the pinouts will be almost the same, but better to confirm from the datasheet
can i use 60v 7ah battery for this circuit? can it power the inverter and make it function well? i am asking this question because i want to connect 12v 7ah in series. Thanks waiting for reply
Swagatam said…
yes 60V 7AH will work and will provide around 120 watts of power....
Chandana Aponso said…
Dear sawagatam

second circuit what is CT and RT value please explain

Swagatam said…
Dear Chandana,

It decides the frequency of the inverter, you can select it appropriately for fixing 50Hz at the output
ainsworth lynch said…
is it possible to get 3000-6000 watt transformers for inverters, like 12v or 24v- 100v ac, because I can never find transformers like that.
Swagatam said…
no not possible, these will need to be made-to-order
ainsworth lynch said…
I realize the ready made inverters dont carry big transformers not even for something like a 3000 watt, is there anyway I could do a transformer setup to give me powerful wattage of 3000watts and above without getting custom made transformers?
Swagatam said…
what you are referring to are inverters using ferrite core transformers, exactly similar to the one discussed in the above article.
TonyBen said…
Hello Swagatam , you recommended IRF3205 to be use at the output of the H bridge stage that has rail voltage of 310v. Can that mosfet handle such high a voltage.?
Swagatam said…
Hello Tonyben, IRF3205 will not work since it's rated to handle only upto 55V....instead IRF840 would be more suitable for the mosfet bridge network circuit
Swagatam said…
I have done the required correction in the article, thanks...
TonyBen said…
Hello Swagatam, thanks for the good work you doing.
Can i have your email? i want to discuss a design idea with you to see what input you could make to it.
Swagatam said…
Thanks Tonyben, my email ID is admin@homemade-circuits.com
ainsworth lynch said…
I would think so, I think those transformers normally have some yellow plastic covering the coil windings, so if I wish to achieve those results are you saying I would have to use ferrite core transformers?
Swagatam said…
yes all battery operated compact inverters rely on ferrite transformer, there's no other option...
TonyBen said…
Hello Swagatam, did you get my email on the design idea ?
Swagatam said…
Hello TonyBen, I received an email from Mr.McAnthony Bernard, I believe it was sent by you.

Let me assess the requested design, I'll try to figure out an appropriate circuit diagram for the same and post it for you...soon.
TonyBen said…
Hello Swagatam, yes i did sent the mail. hope to hear from you soon on that.
Swagatam said…
sure Tonyben, it's in the que, will try to finish it soon....
ainsworth lynch said…
ok then, so I guess I have to figure out how those transformers work, and so far they seem more complex that iron core transformers. It seems as if the circuits have to e designed to use ferrite core and it cant be replace with a iron core.
Swagatam said…
in fact these are much easier to wind than iron core trafos, the only disadvantage is that you cannot get 50Hz or 60Hz frequencies directly from ferrite topologies, rather will need to process the output through a bridge driver network for achieving it.
ainsworth lynch said…
Well first I have to understand how those transformers work, normally I expect to get for example 6v between 2 leads to go to an iron core transformer and the battery making the third, with a ferrite core I don't see a voltage rating, so I don't know how to apply it to a normal circuit or any circuit at all
Swagatam said…
just Google "how buck/boost converters work", you'll get plenty of articles explaining the concept online
ainsworth lynch said…
I read up about both converters and understand them.

if I plan to build this inverter could I buy the ferrite core transformer if so what specifications would I ask for how could I identify the transformer by specs?

with this exact circuit could I use a 12v dc input with the ferrite core? if so then I would assume the output voltage would be 120v in my case but the frequency would be lower than 40khz, if I am correct about that then would changes have to be made to the lower circuit to then get 50hz at 110vac?
Swagatam said…
I don't think these would be available ready-made, you'll have to get it wound from a transformer winder or simply do it yourself with the help of a winding machine.

for acquiring a 120V RMS the output from the first circuit will need to be around 160V DC, so the transformer will need to be wound as per this value.

the lower circuit can be kept as is for a 160V input and 60Hz frequency
ashutosh das said…
sir please can you provide me the connection diagram for wireless power transfer using high frequency transfer....and about high frequency transformer(220v,50hz as input to 12v,40khz output)....
Swagatam said…
Ashutosh, presently I do not have this circuit, I'll try to investigate and let you know if I happen to find any...
sandu si atat said…
salut ! imi poti spune te rog cate spire trebuie in primar si secundar pentru o tensiune de 12v in loc de 60v pentru un transformator de ferita, seria EE70. Multumesc !
Mi Bhiwani said…
please give the detail of L1 such as truns, core size,wire gauge etc

i am doing a 555 inverter project,
currently i sucessfully built a low power inverter 50hz using 12v 60w trafo. i could light up one 20w cfl only.
battery used was 12v at 7ah capacity.
now, i have a 100w transformer rated at 12v in a 2wire primary and secondary config.

IC 555 datasheet says something like this,
"high output current can source or sink 200ma"
that means a single 555 can output 200ma current at pin 3 (i am referring to astable config. only), am i right.
so i though if i need more current, i should parallel 2 555 ics. i.e.,i could get upto 400ma at pin 3, am i sensible? should i do this?
OR should i go in for sophisticated driver ics like 2153 at least in my 100w inverter project?
if i plan to use the 2153, it has 2 outputs, how should i buffer the outputs into a single output so i can pass it to a 2wire trafo.
please help me.

Swagatam said…
Dear, that doesn't make sense, the IC 555 is an oscillator, timer IC, it cannot be used like a power device...and anyway it would never be possible to parallel them for an inverter application.

so you must go for a professional driver IC, may be by connecting two half bridge ones.... or a single full bridge IC..as shown in the following links


Swagatam said…
...just Google "half bridge inverter circuit" you'll get the required design online
Dear sir,
In the ir2153 ic connection, certain circuits has a diode placed between pin1Vcc and pin8Vb pins, in your circuit you have shown pins 1 and 8 shorted. what is the function of that diode ?

If i set the oscillator components to output a 50Khz, will pins ho and lo show 50Khz or half frequencies on both pins?

Again, how to buffer the high and low outputs into a single clock output?
Swagatam said…
Dear Sherwin,

The diode is placed when the Vcc and the high voltage line are joined together via a resistor, but here both the lines are separate, and Vcc is powered from a different power source.

it will be 50kHz for both the outputs....this is what I assume

the outputs cannot be made into a single...and it doesn't make sense..
Summon Skull said…
1) if I use 12v battery source to power this circuit will I need to change anything for example to ferrite core transformer?

2) if not will it step up the same 12v dc to 220v dc at 40khz?

3) Suppose I decided to use the 50v center tap transformer you said we could use in place of the ferrite core would it still be a 50v center tap transformer if I used a 12v battery supply?

4) And using a iron core transformer would it still produce the same 40khz or would I have t get a iron core transformer made specifically for 50v ct and that can operate at that frequency?
Swagatam said…
yes the primary winding 5 turns will get smaller with a 12V supply

since the secondary winding will be 220V so the output will also be 220V

the battery voltage and the trafo primary should match, for a 12V batt you will need to use a 12-0-2V iron core trafo or a9-0-9V iron core trafo

for iron core trafo the frequency will need to be changed to 50Hz for 220V output and you won't require to build the last circuit
for the above circuit what should be the ideal frequency output of the ic to drive the ferrite transformer?

secondly, i wish to build a low power version of this ferrite inverter say 100w and input to circuit will be 12v.
for 12v input how many turns would i require at the primary of the ferrite trafo and how many in the secondary?
Summon Skull said…
So if i want to use the ferrite core I would have to use 60v from my batteries as input nothing lower for that specific circuit?

I want to try ferrite core so I would like to give the manufacture specs to work from to build it, would I just let them know that I need the primary to handle 60v and the secondary should produce 220v at 40khz or should I tell them to wrap 5+5 turns on the primary and 18 turns on the secondary.
Swagatam said…

it's given in the article as 40kHz, the number of turns decide the frequency and vice versa.
use 2 + 2 turns at 40kHz, secondary will be as is.

Swagatam said…
You can use any desired voltage and current as per your preference, by just modifying the primary side of the inductor...please see your previous comment for the answer

the calculation is very linear....for 60V if it's 5 turns, then for 12V it becomes 60/12 = 5/z = 1 turn

or 1 + 1 turn @ 40 kHz
Summon Skull said…
ok makes sence, so finally ill as because in the info about the build of the inverter its changing the DC voltage of 60V to a higher 220V at a lowered current im not sure how low the current would be.

so my question is a manufacture may ask me what input current or output current do I expect to get from the transformer what would I tell them? (remember in my case I would be using 12v supply what would the current be for that voltage range, secondly what would the current be for 60v in case I want to try that also.)
Swagatam said…
what is your requirement? how much watt do you intend to acquire at the output?
I am making a LOW POWER version of 100 watt only, here i need your help.

1. For the trafo to oscillate at 40khz, would i need to configure the 2153 outputs to a bit higher frequency say 45khz, since i think there could be a frequency drop after connect the trafo to the circuit.
Is that changing necessary here.

2. I got the ferrite trafo ready for this inverter circuit, but it is an EI core. salvaged from an old pc power supply.

3. Should i need to add spacers between the core pieces? if you suggest some please specify me which material.

4. I noticed in some ferrite trafos, manufacturers add a copper sheet between the windings, what purpose does it serve? should i add it when rewinding the trafo?

5. For resistors what does the tolerance value mean, i have heard of 1% and 5% tol.and which type is best? at what wattage are the 2r7's rated at?

6. What diodes are dsem2-06a in the diagram, picture represents a zener type, there is no google response for the above value, any substitutes?

7. What is the purpose of the coil in series with the diode?
I am building this circuit from today so please help
Swagatam said…
Sherwin, the answers are as follows:

1) the frequency will not drop, but anyhow the 40kHz value is not critical, it can be little here and there.

2) EI core will do.

3) use paper pieces as spacers between the EI contact surfaces.

4) it's for an increased isolation and suppressing noise, but PVC insulation also works equally well and offers good isolation.

5) tolerance refers to the slight value difference between the actual measured value against the printed value

6) refer to this datasheet:


7) It's for protecting the diodes from switching transients
the 5kva schematic needed 10 wires to be wound simultaneously while winding the primary;
but since i am trying the low power version i want the circuit to give 100w at the output only.

1. for 100w output, while winding the trafo how many wires would i need in parallel in primary and sec.

2. would 2 mosfets be sufficient on each channel of the ic outputs for 100 watts of power.
Summon Skull said…
I would aim for the same 5000 watts but because i am using 12v supply i am wondering what curreent ratting would I need to tell them to make the ferrite core at
Swagatam said…
if you divide 5000 with 12 you will get the required amperage value for your transformer.
Swagatam said…

I don't have the calculations, you will need to do it with trial and error.

two mosfets (IRF540) would be more than sufficient for 100 watts.....or even 1000 watts.
now i will build the trafo as you described in the article, but will use 2 strands of wire together for winding the pri and sec.
also, the circuit part has almost got completed, yet to attach fuse and heat sinks.
I will tell you the results within a day or two.

some day i happened to salvage a toroidal core from an old computer power supply i purchased second hand. Its specs are;
Core color is white/yellow
The outer diameter measures: 1.06”
The inner diameter measures: .57”
The height is: .44”
are the given specs. enough for winding up the core and building the transformer.
Just want to keep the toroidal core as an alternative.

Summon Skull said…
Ok kool I did that before but I got 416.6 amps I was just wondering if a ferrite core would really push that much amp, and I thought the amps would be lower than that on the ferrite core and then stepped out at the output of the second circuit by the output fets, but thanks for the info Ill pass it on t them and then get back to you if anything.
Swagatam said…
sure, all the best to you.

hope you succeed with the project, because this design is strictly for the experts and you are fairly new in the field.
Swagatam said…
OK great. thanks for the update
Swagatam said…
the calculation is correct, but the value looks impractical.....that's the reason the voltage needs to be more...even 60V will require 5000/60 = 83 amps, which is huge

the fets and the trafo together have to handle this massive current in order to produce the output wattage
Summon Skull said…
Thats exactly what the manufacture just told me. I actually need 120v ac from the output of the inverter so I told him the output should be about 160v from the ferrite core instead of 220v, also is it possible for me to actually input 12vdc from the source and use a dc-dc converter to step up the 12v to 60 volts or higher to feed the circuit so that I can use smaller wires to achieve higher power.
I'm done with the winding of the trafo, here i did some changes;
1. i used 5+5 turns in primary and 20 turns in secondary

2. i had the ei core trafo on hand but still preferred the toroidal core.i used two core pieces.

3. i unwound those cores, glued them with fevikwik and kept aside.

4. once both core attained firmness, i covered the cores with yellow adhesive tape.

5. i then begun winding the core.

6. after finishing i attached the trafo with cable ties and then covered with tape.

7. i tested for shorts between windings and then connected to the inverter circuit.

as stated in previous comment i used two mosfets on each outputs of 2153.
Now the whole circuit is ready.

i then connected 60w incandescent bulb.

i then attached my 12v 7ah battery,

WOOOOOOW the bulb glew at full brightness, i couldn't imagine

ONE THING frequency finally was set at 60KHz.

I'm finally done with this project.
i appreciate your kind replies to every comment stated by me.

Swagatam said…
That's amazing Sherwin, I wonder how you could succeed at the first attempt since you are a newcomer in this field.

anyway that's a great achievement.....congrats to you...and keep up the good work.
Swagatam said…
if you use a DC to DC converter that would again demand 400amps for the 12V for boosting the value to 60V at 83 amps...then feed this 60V / 83 amps to the above inverter to get 120V @ 40amps...

so why not boost the 12V to 120V directly....
The bulb 60w is glowing at full brightness similar to driving even on ac mains.

Indeed, my ferrite inverter circuit got completed at the first shot, since i did so by inspecting every stage of my unit.

I tested for possible shorts between all connecting points in the circuit.
I tested for the output frequency it were 60KHz(i set it manually).
One thing is i connected diode between pin1 and pin8 of ic, here the above circuit showed pins 1 and 8 short being connected to positive,

I did dummy test on breadboard of the ic 2153 only,
shorted pin1 and pin8 of ic, then connected the oscillator components and added bypass tantalum cap,

Then i realized the importance of the diode between the ic pins.

After connecting this diode, only then the ic began oscillating smoothly here and i set the frequency at 60KHz
Now there is no heating.

Once i began to connect the ic outputs to the rest of the circuit, my circuit then worked properly,

I finally then checked whether or not i'm getting frequency at the final respective mosfet drains, here everything worked normal and output frequency was 60.08KHz.

i finally connected the transformer, proceeding with connecting a 60w light bulb. Here the bulb glew instantly,
on the other hand i was shocked to see the way the bulb lit,

Indeed, credit goes to you for providing all circuit details, i am really thankful for that.

I am looking forward to even help other newcomers in building this project since this project was very easy to me.

Yet to tell you the CURRENT CONSUMPTION of the inverter circuit at different loads, i will do so as i get time.

Once again,
Swagatam said…
Hi Sherwin, thanks for updating all the info, all these look very impressive.

However the diode across pin1 and pin8 does not have much significance according to me, because connecting the diode will make pin8 just 0.6V less than pin1...so if pin1 is 12V...pin8 will be rendered 11.4V with the diode...so this doesn't look like something crucial that would alter the circuit's performance

but anyway I appreciate your efforts a lot....and hope to see more from you.
Swagatam said…
sure!...many thanks to you.
The current consumption of the inverter are as under;

3.56 amps for a 25w bulb
3.88 amps for a 40w bulb
4.05 amps for a 60w bulb
3.65 amps for 25w soldering iron

Even a 100w bulb worked! circuit drew almost 4.8amps(~4.77).

This experiment happened sucessfully only since i happened to buy a cheap trafoless chinese inverter and studied their circuit.
These inverters were rated something like;
Output-150w continuous 180w maximum

Few of these came in the market, old and tattered in fashion, some were good and their shape was in a coke can type, and also had few nice features.

I brought one home and connected a 100w incandescent at its output.
The moment i powered them, i was shocked the way the bulb glew, i wondered damn what circuit they have used.

I will give you the details of the coke can inverter circuit as i am free.

Swagatam said…
Sherwin, sorry I am confused, which circuit did you build? The one which is shown in the above article or the Chinese inverter circuit??

and how the above circuit and the Chinese inverter circuit be related?? please let us know about it?
I built the ferrite inverter circuit shown in your blog and it was very easy. I made it such a way that i got results in a first shot.

The chinese inverter that i bought its circuit were far more complicated.

What i did was;
1. i removed the fer.trafo to study its winding schematic. It was an EE trafo and had 4 pins on the primary and 2 on the secondary

2. Moreover, i didn't open the trafo and inspect the winding to see how the pri and sec were wound, its turns,etc. since its core pieces were glued tight.

3. I kept this trafo aside and may attach it to your ferrite invt.circuit in the blog and see how much it can output.

To make things clear, i made the circuit which is in your blog and it worked well, on the other hand i had a chinese trafoless inverter and i seen how they made it.

You may have wondered that i made a replica of their circuits by looking at them and making it on a veroboard.
I just opened one of their make to see what components they used. Nothing else. Now i'm planning to use their circuits' trafo only and connect it to your circuit shown in your blog.
The idea behind making this whole project is to make known to the viewers how effectively one can convert battery power into mains ac to use their intended household appliance, without making use of bulky iron core transformers in circuits.

The ferrite core trafo is complicated in design in terms of winding data, wire guage size, type of bobbin used, the core size, etc.
But for me all these was just a piece of cake!

I knew the difficult part in the inveter circuit is the ferrite core trafo itself, so i prepared myself thoroughly into making it and sourcing the raw materials for building the trafo. was not at all difficult rather easy since all materials were readily available in the market.

Thats it, everything done well.
Swagatam said…
OK Sherwin, thanks for the clarification, however the salvaged trafo might not work with the above circuit, because inverter transformers are specifically designed and matched for their own specific circuits, so you'll need to be careful while doing it.
Swagatam said…
That's indeed commendable Sherwin, we all appreciate your efforts and wish you all the success for your future projects too.
Summon Skull said…
I keep posting but I am not seeing it here, is it because I posted a link of the other circuit?
Swagatam said…
yes that's correct, but I have replied to all your comments and then deleted it afterward, so I hope all the replies are still stored in your email, you can check it out.
Summon Skull said…
This is the first reply I got since you told me so why not boost the 12V to 120V directly. and I sent a schematic asking you if that can work whic was basically an inverter with a power supply converter the 120v ac to 120v dc and I was saying how I would change the transistors to fets for higher power, basically I want to know if that can work and I step it up to 120v would the ferrite core would be primary 120v secondary 160v or should the secondary be 120v also because at the end of the circuit I need 120v ac to my load at 50 hz
Swagatam said…
you are supposed to get all the replies in your email, if you are ticking the "notify me" box before publishing your comments.

with a 12V supply you will have to use 400 amp current for achieving 5000 watts, there's no way of escaping this requirement regardless of what technique you may employ.

Summon Skull said…
its automatically ticked and not even the reply you just gave I haven't received in my email and I normally receive them there, anyway ok I understand what your saying but my second question that I have been asking, in my country I use 120v using 12v as the suply ignoring the wattage what output voltage should I get from the ferrite core I am asking if it should be 120v or is it 160v because I want to know what to tell the person who is wrapping it to what I need from it and also I need 50hz to operate my load
Swagatam said…
It's 120 that you need to tell the winder...after rectification this might become 160V
Summon Skull said…
thanks I think ill also try one for myself also for learning purposes.

question 1) I realise that the core has 2 sides based on pics above, after winding the coil and placing the 2 sides together would I have to tape the outside of the core itself to keep it firmly together because it seems it would fall apart to me.

2) based on the first schematic the transformer looks like it has a center tap so if i was to wrap 5 turns then insulate it with tape then wrap 18 turns then insulate it with tape then wrap 5 more turns how would I get that middle leg going to the battery positive? Is it that ill join 1 set of the 10 strands of the first winding to 10 strands of the second winding then use that as the center leg?

3) If I was going to use 10 strands of wires to make 5+5 turns I would end up with 20 strands of wires so would i just terminate each side of 10 wires to a terminal block then send 2 wires out from each side?

4) since I will be using 120v how much turns will I need to make for the secondary?

I tried to use the salvaged transformer from the coke can inverter.
but before that i protected the inverter circuit with a 12v 20w incandescent lamp.

i would give a detail of the winding of the coke can ferrite trafo:






The primary data:
From pin A two wires feed inside the trafo,

One of the two wires connected from pin A ends at pin B.

From pin C one wire enters feeds inside the trafo

At pin D two wires end.

The secondary data:
At pin E one wire feeds into trafo and end at F
At pin F another wire feeds into trafo and end at G

Coming to how this trafo was connected to the coke can circuit:

firstly, the oscillator circuit were designed in a push pull config. where i also seen 2 irf3205 mounted on seperate heatsinks.

The outputs were connected to the trafo as follows:
a. drains of 3205's were connected respectively to pins a and d
b. trafo's b and c were shorted connecting to + battery........................the primary side

c. pins e and g of trafo connected to the rectifier circuit which consisted 4 pieces of M7 diode and one 6.8uF 400v capacitor.

These were the details of the trafo connection to pcb.
And YES the salvaged trafo worked with your blog's circuit that i prepared.

Here, i rectified the above trafo's secondary output i got 321.6 volts dc.

The toroidal trafo that i made i got 315.7 volts dc at secondary rectification.

I also checked for any unwanted heating of components after attaching the salvaged trafo on the inverter circuit, none were there and everything worked normal.

For final confirmation i attached the incandescents that i did previously, all worked well, brightly using the salvaged trafo.

Once again the 'salvaged' victory that i attained!!!

Swagatam said…
The "start" of the outer 5 turn winding will join with the "finish" of the inner 5 turns and this joint will become the center tap.

treat the 10 strands as a one wire and wind them together, and join the outer and inner start and finish points to amke the center tap, as explained in the above sentence.

use 9 turns instead of 18 for getting 120V

make sure to separate the upper and lower core surfaces which join each other face to face with paper or with the insulation tape itself
Swagatam said…
That's great Sherwin, I really appreciate your cool head and intelligence.

I think instead of writing such interesting facts in comments, you should publish them as posts for this site and contribute to this site. That will also allow you to earn a handsome passive income from me.
Summon Skull said…
by way what actually brings the frequency so high is it the ferrite core itself or is it the circuit feeding it?

if its not the circuit that mean putting a normal 12v -120v iron core transformer at the end of the first circuit would give me 50hz at 120v
Swagatam said…
it's the IC that's responsible for generating the frequency, as per the core requirement...the parts associated with pin2 and 3 can be altered to reduce the frequency to 50hZ and an then iron core trafo can be employed instead of the ferrite core....
omooh Kole said…
thanks for the circuit, but i need to know, wont there be a need for output voltage correction circuit or with the H-bridge, there is no need, cos i know in inverters, output voltage drops when loaded
Swagatam said…
that's a secondary circuit and can be included if one requires, here the main thing is to make the ferite inverter successfully, afterwards other add-ons can be included....
Unknown said…
Can I use transistor 5r199p instead ixfh50n20 .and i use 4 transistor 5r199p.and also use 12 volt instead 60volt.and i want to design transformer again.
Swagatam said…
what's the voltage and current rating of 5R199P??

how much current do you intend to acquire from the inverter?
Vahid Asadi said…
current rating is 17 A and VDS=550 volt.and i want inverter output is 1000 watts .out put current is 4.5 amper.and input voltag is 12 volt.ishoud I use How many of these transistors 5r199p.
thank you
Swagatam said…
mosfets will not produce watts for the inveter, it's the battery power first which must be correctly rated, and then the transformer, and lastly mosfets can be considered...

at 12V, the current from the battery must be 1000/12 = 83 amps...so the battery will need to be around 12V 500AH
Vahid Asadi said…
So if I use the 4 to the transistor 5r199p.and battery had 12 volt 70 amper.i can,how much power will be in out put?and What is transformer details.and do battery 12 volt 500AH produce 5000watt or 1000w?
thank you for attention
Swagatam said…
I don't know about the specs of 5R199P please confirm it from the datasheet...
The battery AH rating must be 10 times that of the required watt/volt from the inverter.

so ideally a 500AH would be able to handle only 600 watts
Vahid Asadi said…
if iput voltage is 12 volt 500 amper, input power is 12*500=6000watt.(p=vi).but if battery is 12 volt 70amper input power 12*70=840 watt and output power is about 700watt.it is true or fulse?
and How do I calculate the amount of MOSFETs needed?
thank you
Vahid Asadi said…
(The battery AH rating must be 10 times that of the required watt/volt from the inverter).why???????
thank you
Swagatam said…
It's AH, which is ampere-hour and is different from ampere...it means if you discharge at this rate it will last for 1 hour....but practically it will be not more than 20 minutes.

mosfets V and I should be twice of the required voltage and current spec of inverter.
Swagatam said…
because lead acid batteries should always be charged or discharged at around 10 times less current than their AH value, for preventing damage to the battery.
Vahid Asadi said…
i understand.please give an example for(mosfets V and I should be twice of the required voltage and current spec of inverter.)
current rating mosfet is 17 amper and voltage rating is 550 volt.if out put current inverter is 3 amper and trensformer is 12 to 220 volt.and battery is 12 volt 500AH.
thank you
Swagatam said…
The output wattage is not relevant, it's the battery consumption at any instant which must be considered...if the battery voltage is 12V and max current consumption is 50amps by the inverter, then the mosfets could be rated anywhere around 30V, 40V, 50V at 100amp, 70amp, 80amp etc.
when we rectify the mains 230v ac into dc, we get 325v dc,
my question: is this rectified voltage equal to ac mains peak voltage?

coming to the ferrite core trafo in the above circuit, we have
5=5 turn in pri and 18 in sec,
the voltage induced in the 18 turns is 220v at 40khz,
now this voltage cannot be measured by a multimeter due to such huge frequency.

After rectifying this 220v high frequency voltage i get 311v on my multimeter.
Can this voltage (311v) be called the peak value of the High Frequency rectified voltage??

Now if i divide the 311v with root2 i get 220v.

HERE, can i call this 220v as the high frequency RMS voltage at the output of the ferrite transformer??

Are my above calculations proper??

Swagatam said…
Sherwin, yes 325V is the peak value of the measured mains AC.

311V is also the peak voltage that you have measured for the ferrite trafo., because after rectification, the reading will be always equal to the peak value.

220V after dividing with roo2 is also correct, it'll be the RMS value

so all your calculations look correct to me.

what is the actual function of a bleeder resistor in power supply circuits??
a day before i were doing a study over an old computer smps, on each dc output rail there were resistors connected after the capacitors.

I calculated their values based on the color dressings:
1. 12v output had 270ohm 1watt, i calculated the current through ohms law and got 44ma.

2. 5v output had 100ohm 0.5watt, calculated current is 50ma.

3. 3.3v output had 15ohm 1watt, current is 220ma.
before i proceed, are these calculations right??

my thought,
i noticed the resistor at the 12v output rail it were 270ohm 0.5w MFR and it burned such that it made the pcb black at that spot. fortunately its color dressing were identifiable thats how i got to know its value.

my question,
while making a power supply circuit, should i include a resistor after the capacitor stage and is it really important to have one in circuit??


i made another transformer ready for the inverter circuit,

1. i prepared another circuit today and kept the oscillation frequency of 2153 at 50khz.

2. the ferrite trafo primary i wound 7+7 turns using 3 wires in parallel and for secondary i used 2 in parallel with 20 turns.

3. mosfets on each section were 2 irf3205 in parallel, gate resistances were 12 ohms 2w resistors.

4. i converted the hfac o/p of trafo to dc. this time i got 330v on my multimeter(reading 329.7)
i prepared till this point and stopped.

my question,
now with this peak voltage can i directly operate the cfl lamp or an incandescent else there is danger of explosion??

Swagatam said…

It's a calculated dummy load which becomes essential for most SMPS topologies in order to keep the circuit stable even during a "no load" condition.

When there's no load connected this resistor load acts as the minimum specified load for the SMPS and prevents it from getting unstable and from a possible damage.

your calculations are correct.
Swagatam said…
Sherwin, this peak voltage appears to be within the normal working range of all 220V RMS rated appliances, so according to me it's fine, you can go ahead with this peak level.
javeed ahmed said…
dear Mr Swagatam Majumdar thanks for the donated circuit.can 1500wt air conditioner be run on this 5kva Inverter ?
Swagatam said…
dear javeed, 5kva = 5000 watt approximately.... so yes 1500 watts can be operated through it.
javeed ahmed said…
Dear Sir Majumdar, thanks for your kind service to we electronic hobbyists and man kind.My request is, please let me know,whether the Inverter is purely sine wave? And appliences like refrigerator,airconditioner,plasma TV etc.....can be undoubtedly operated through this non re-payable gifted Inverter by You selfless personification so.Wish You cheerful happy new year and never ending Ideas to you from Almighty God Creator.
Swagatam said…
Thank you dear Javeed, wish you too a very happy new year!!

The above circuit is a ordinary square wave inverter you will have to insert a PWM feed in order to convert it into a PWM sine wave version which can eb a little complex.
javeed ahmed said…
dear sir,would please modify its output with PWM source and facilitate to make use such an inexpensive and economical design to World wide needy people like us? Hope You will consider my request.Thanking you.Your affectionate reader.
Swagatam said…
Dear Javeed, I'll try to update the design possibly soon...
in one of your previous comments you mentioned to me;
Instead of writing such interesting facts in comments, you should publish them as posts for this site and contribute to this site.
Dear, how do i do so??

i found a new formula for calculating capacitors in series, here goes it:

Suppose we have four capacitors, all non polar type rated at 440v and having 2.5uF capacity.

Now, my formula is;

Total value of capacitors divided by number of capacitors square.

so we get,

2.5 + 2.5 + 2.5 + 2.5 = 10
no.of capacitors = 4 sq

so, 10/16 = 0.625uF i.e., 625nF

Sir please think over it and tell me that is such a formula correct??

Swagatam said…
Sherwin, please refer to this page:


for further questions you can email me at the given address.

Swagatam said…
Sherwin, I'll let you know after confirming it.
Swagatam said…
...it will work only if the values are identical, not with nonidentical values.
Ainsworth Lynch said…
for educational purpose for me I would like to know within an inverter using ferrite core why is it necessary to use high frequency, based on what I understand is that you would feed 12v from your battery to FETS, then an Ic would pulse the Fets to send out a high frequency dc to ferrite core transformer, so what I always wonder is if that same 12v dc were to be chopped up at 50 or 60hz and sent to the ferrite core wouldnt it be the same, since generally the ferrite cores are low wattage.
Swagatam said…
50/60Hz may be suitable for iron core trafos, but ferrite core trafos can work only with high frequencies in the range of 20kHz and above for producing efficient results.
Ainsworth Lynch said…
Ok thanks that was straight forward, I dont want to take up too much of your time, I would like to know if you have a specific article I could read up on them where It concerns understand how they work I can seem to find out about the turn ratio, I actually want to give ferrite core design a try now that I realize that to get high power inverters its better to use ferrite core, I would like to know what types of cores I could by and how to wrap them to get for example 12 t 120v from it or if I was to order it what would I look for in terms of turn ratio since thats how I see them listed.
Swagatam said…
ferrite core allow you to get high power in compact sizes, that's the only main advantage of a ferrite core trafo over an iron core counterpart

you can refer to this article which explains the basic winding formulas for ferrite core transformers:

Gogo Friday said…

Please am seeing two different diagrams here, where will the second diagram be?
Gogo Friday said…
Please sir Can you give me the list of everything needed to run circuit?
Ainsworth Lynch said…
Ok thanks, looking at the inverter in this article I always wondered what was missing but I realize that you didnt add a circuit for the rectifier stage, how much capacitors would should I use in parallel for this circuit for the rectifier stage.
Ainsworth Lynch said…
Ill be using 120v out from the 1st circuit so ill be feeding 160v to the second circuit, where it says load on the second circuit I hope it doesnt require a iron core transoformer there, just testing between those 2 points marked load, will I get 120vac 50hz? since thats what I desire from it. Adding a transformer there would defeat the purpose of using this design so I hope I dont need one there.
Ainsworth Lynch said…
Also is this a square wave, if so it wont be able to run electronic circuits, I think I saw you with a modified version with a pwm feed, can I have the link and would it be able to run the most common electronics like smart tv, radios, fridge ect?
Swagatam said…
you may refer to the following article for all the required details:

Swagatam said…
when the first circuit is already creating 160V then obviously there would be no need of any other form of step-up transformer, so yes the load can be directly connected across the indicated points.

you are supposed to get around 120V across these points if the first circuit is correctly generating 160V DC
Swagatam said…
the following modifications might help to convert the above design into a reasonably good sine wave version:

Ainsworth Lynch said…
ok thanks, for some reason I have been searching the internet to find information on ferrite core transformers to me it seems its not so popular with english speaking countries I cant even source it online I was trying to see if I can get 1 to buy at 12v to 120v but no luck unless there is something that I dont understand about them.
Swagatam said…
ferrite inverter transformers are never available ready made...they need to be made to order
Swagatam said…
you can tell them about the winding specs...or the voltage, current and the frequency specs, that would be more than enough for anybody to design the trafo
Ainsworth Lynch said…
I forgot that I ordered an E-80 core, I have some copper wire I was wondering if I should wrap take around the inside part of the core before I start to wrap.

Should I place paper underneath the ends of the core to prevent them from touching and also I was planning to use tape to tape it together.

Since to core is separate should I wrap all the turn on one side them put the top section on to the half that I made the wrap on, or place then together tape it up then start to wrap?
Ainsworth Lynch said…

This is the core and wires

Just doing 1 wrap for 12v and 9 wraps for 120v out.. After that can I test it by hooking it up to my power companies ac supply of 115v?
Swagatam said…
you will need to wind it over a hard plastic or a similar non-conductor bobbin, and then gently insert the bobbin winding assembly inside the E-core as shown in the image.

this project is strictly for the experts.
Swagatam said…
yes, only if you want to see a big explosion, fire and blown fuses.

ferrite cores work with high frequencies in the range of 20kHz to 100kHz.....the home AC is specified only at 50Hz or 60Hz.

the above project is strictly for the experts who are well versed with all the basics of power electronics.
Ainsworth Lynch said…
I know that it works from high frequency and I didn't mean I would connect it to the circuit in this article immediately after wrapping, I'm not an expert at electronics but I don't know all things especially about ferrite cores because Information on it is hard to find.

What I was asking you really was if it's possible for me to test it like test the voltages without connecting it up in the inverter circuit, if not it's ok... I just though I could test it like how I would test an iron core if I wrapped it.
Swagatam said…
It is not hard to find about ferrite cores on the net, there are plenty of articles regarding ferrite core transformers, basically it comes under "power electronics", so you can obtain all the info under this subject.

there's no other way to test a ferrite transformer other than using high frequency
Ainsworth Lynch said…
Ok I was wondering Can I use irfz44n Fets instead of the fets used in this schematic in the ir2153 section since I am using 12v supply, also I have some 6amp shottky diodes can I use those to replace the 4 amp general purpose diodes? The 47uf 25v capacitor connected to ir2153 did you mean to write tantalum?
Swagatam said…
yes IRF44z can be used.
the specified diodes can be used at the indicated places.
the 47uF cap should be a tantalum type preferably.

12V will not allow more than 500 watts output
Ainsworth Lynch said…
Ok then Ill try the 6 amp diodes I have and use the irfz44n's but since the minimum I require is 1000 watts ill go for 24v primary then. I forgot to ask I cannot get any 10mh inductors presently can it be replaced by resistors or can I use copper wire and make a coil to replicate it, if so what should I do.
Swagatam said…
OK will do,
the inductors are 10uH not mH....you can build them by winding a few turns of magnet wire over a ferrite bead or any suitable ferrite core
Ainsworth Lynch said…
Ok then I will use the 555, you didnt get back to me about the tl072 puresinewave generator found in your forum, what If I wanted a clean sinewave wave out wouldnt that be better even though I know its less effecient.

I am buying up some parts now so just want to make sure of everything.
saw some diodes (RURG3060) was thinking about using those in the rectifier stage also I would just get 8 irfz444n for the high frequency stage and use 4 more for the H-bridge stage also.

I see on the IRS2453D that there is Ct and Rt what value resistor and capacitor should go there?
Swagatam said…
you will need to build the circuits stage wise, otherwise troubleshooting if any can get difficult...so first build the 300V stage with success and then we can proceed for the sinewave processor section either by using iC555 or an opamp, whatever suits best.
Swagatam said…
you can use any value for the Rt, Ct and then check the frequency for those values, once you get the frequency, you can calculate the required values for 50Hz through cross multiplication.
Hello sir,
i have a powersafe600 series UPS, its rating being 600va/360w

Just thinking that the trafo were a stepdown type...
1. on the primary side there were 4 wires.
2. on the secondary were 2wires (heavy guage copper coil).

i tested this trafo seperately feeding AC correctly on the primary side and on the secondary i got 6.2v AC.

Now what i wish to know is:
1. How much is the secondary coil current rated for, and which factor should i take, is it the watts or the volt-amps?? and then divide it by 6.2??

Now, taking the watts and dividing with sec.voltage i get 58 amps
and taking the volt-amps, dividing with sec voltage i get 96.7 amps

here, which factor is proper in consideration??
Swagatam said…
Hello Sherwin,

use volt x amps, it will give you the most appropriate results
for any oscillator when programmed to output a particular waveform, eg., square wave here and when seen on an oscilloscope we see the square waveform but with some (sort of disturbance) noise on the generated waveform,

my question is: How to suppress this noise and get a proper square wave?

Swagatam said…
you can suppress it by adding an optimized inductor in series with the relevant signal output
i rewound an EI35 core trafo from a PC power supply,

1. Battery i used 12v 10AH as my input voltage, making another inverter circuit keeping the components as is.
i set the 2153 to 40KHz perfectly using a trimmer.

2. the ixfm series mosfets were quiet costly so to save on bucks, i decided to parallel four 3205 mosfets which mounted to 55v 440amps.
i used four on each 2153 outputs.

3. for the transformer, this time i wound pri.8+8 turns and sec.20 turns.
Now, my circuit ran quiet fine and i could power a 100W filament bulb at full brightness.

One thing, the rewound trafo was humming enough to give me a headache, so i decided to clip off unwanted noise by adding ferrite inductors at each outputs of 2153 and filtered with 10n caps.
After that the hum were completely gone.

One good thing is that using 8+8t in pri, the trafo was barely warm on full load.

Comparing it with the 5+5t trafo that i rewound previously it got hot on full load.

4. I cracked the turns idea by thinking in this manner:
Input is 12v keeping in mind this is peak dc of an unknown ac voltage.
I divided this with root 2 and removed its AC equivalent voltage and got 8.48v

5. So 12V DC = 8.48V ACrms i decided to wind 8 turns and finally cracked the high frequency trafo winding theory!!!

Swagatam said…
That's amazing Sherwin, in fact we are the ones who are really thankful to you for verifying the design and improving it with such determination and accuracy.

We all appreciate the in-depth info that you have so far provided to enlighten the many needy enthusiasts reading this article.

keep up the good work, and keep posting..... thanks very much.
What would you suggest in order to prevent iron core transformers from catching corrosion on their body?
Swagatam said…
Hi Sherwin, to prevent corrosion and rust, the iron core should be coated with a thick layer of varnish, and then after drying, it should be applied with additional layers of thick good quality oil paint
Sir does a Ferrite core transformer outputs the voltage in terms of pulses ?
i have a circuit of LED street lamp with me .. one ferrite core transformer is used at the output stage of the circuit... 230 V ac is first being converted into DC voltage ( about 310 V ) filtered and fed to the ferrite core transformer after some componets ( including one IC ).. the output of this transformer is then diverted to a dual ultrafast soft recovery rectifier ( BYQ28E )... and finally the output is taken from the output pin of this ic and the ground terminal.. but the problem is the leds are flashing continously.... turning on and turning off then again turning on turning off automatically.... when i have checked i came to know that the voltage between the output terminals varies in between 20 V to 100V ... what is the cause for this sir ?.. i am sending you a picture of the board for reference into your hitman inbox... plz check it out and reply as earlier as possible
Swagatam said…
RT, it could be because the load is not compatible with the SMPS output specifications, therefore it is being forced to go in the shut-down mode, reduce the number of LEDs or use a resistors in series to possibly correct the issue
What i have learned and understood by doing this ferrite core inverter circuit is:

1. By increasing the oscillator frequency, the turns count in a transformer can be reduced resulting in the use of much smaller transformer which can still give good power output.

2. Rewinding transformers without keeping AIR GAP between CORE PIECES, worked the best giving full power.
According to me, the EI core transformers were easy to open and rewind without breaking the core.

Till now, i've rewound 10 such transformers and all worked best giving full power output.

I finally attained success building lightweight inverters (only upto 200W continuous, 300W peak) only after cracking the HF trafo winding theory!!!

As for now i've done the inverter circuits to operate with 12V, 24V and 60V with 10 amp/hour rating SLA battery,
But kept my power output limited to 200w continuous 300W peak only.

Thats it,
All done well with careful inspection and good knowledge about electronic components and their various
uses in circuits.......keeps me on the go.......

Swagatam said…
Thanks Sherwin, I appreciate your efforts.

your first point is correct and it's the standard principle applicable for all ferrite based inductors, however getting good results without keeping air gap or a paper gap across the core surfaces looks strange....because without paper gap the cores could get saturated and start malfunctioning.

Anyway thanks a lot for the inputs, keep posting and good wishes to you!
Ainsworth Lynch said…
is it ok to use IRL640A in the high frequency section these are what I found to buy. ( I was wondering if the Rds on if its low enough).
Swagatam said…
please check its max drain/source voltage and current specs....
Ainsworth Lynch said…
I checked for some 600v 20amp fets for the H bridge side
some more wonderful things,
1. I managed to attach two EI cores side by side in order to attain more power output from the transformer.

2. I took both E's first, stuck them firmly with electric tape on each vertical legs.

3. I then made the windings fit firmly on the E's such that they don't exceed the length of the middle leg of the E-core, finally applying tape on the finished windings.

4. Next, i placed the i's on the e's and THIS TIME ADDED PAPER GAP BETWEEN THE CORE PIECES.

5. I finally taped the whole transformer firmly and assured:
a. that the e's and i's are not lose,
b. that the pri and sec windings have proper isolation between each other,
c. that the winding does not have direct contact with the ferrite pieces which would cause a short.

On completing the transformer, i googled the datasheet of the EI33 core and took a note of its maximum power output with respect to the working frequency given in the table.

The datasheet says at 50KHz it can output 125 Watts of power.

So the total power i calculated for combined ee and ii cores is 250 Watts at 50KHz.

But here i tuned the 2153 to produce 66KHz and powered the transformer through four mosfets irf3205 on each channel.

Now i am getting 300 watts of continuous power from the transformer and after rectification got 330volts DC(329.6 on meter).

I got the 300 watts from driving the ferrite inverter from 24volts 20amps of battery power (2 * 12V 20AH sealed lead acid battery).

Making this transformer was somewhat a difficult and challenging task but i successfully completed it.


Swagatam said…
H Sherwin, that's very interesting and valuable information, thanks for sharing, I am sure the new hobbyists will love reading this.
I wish to know what software you use to draw circuits since i wish to design some circuits myself,
I have never done so till now so please help.
Swagatam said…
I use CorelDraw for drawing my schematics.
Ainsworth Lynch said…
What If I wanted to use this circuit to step up from 12v to 400v how much turns would that require on each side of the transformer?
Ainsworth Lynch said…
Or better even 24vdc to 800vac
Swagatam said…
you can use 12 turns on each half, and 400 turns on the other side
Saqib Lodhi said…
Hi Swagatam,

I am going to buy tranformer EI cores. Can you or anyone in your group send me required specs of cores for 5kva or more. as I read somewhere. should E80 type core is suitable for this? please I need all calculations to prepare the transformer like core dimensions including inductance and density and winding wire thikness and turns. Will be really thankfull to you guys.
Swagatam said…
Hi Saqib, I do not have the exact calculations or the inductance data for the transformer, the idea was thoroughly tested by Mr. Sherwin, you can go through all his posted comments and try to grasp the details.
There are lots much to say and discuss regarding this post.

I wish to put out a lot of changes in this design since I've noticed errors in certain places.

I don't know that whether i should join the forum for the discussion or just comment in this section directly.
Swagatam said…
Dear Sherwin, since you have worked hard on this project you have all the right to point any corrections or modifications that may be required in the proposed design, please feel free to post it here, I may further on transfer the data in the main article so that the readers are able to view it easily while reading the article itself...
Saqib Lodhi said…

Hi Sherwin, thanks for this great effort to design this high power circuit. It will be much appreciated if you please post corrections and any other thing which can help us designing error free inverter. also would be much better if you can add pure sinewave conversion section.
Hi Saqib,

Firstly i would suggest you to build a low power version of this design say 150/200W which would require a single EI core transformer.

This could give you a good experience at the beginning stage and then later you may upgrade to high power.

I got the specifications of the transformer if you wish to build as i suggested.
I could help you with other stages of the inverter also.

Just take note of this:
The 5KVA design would be more difficult to accomplish since it will require a lot of complicated checking and inspection at every single stage of the complete design.

The transformer gets more complicated....You will have to stack many cores side by side to get the proposed power output.

You will require large heatsinks and cooler fans for power devices, in order to keep them cool during operation.

The full bridge section of this design will heat up if not implemented correctly and managing them at such massive power(5kva) would be really difficult.

You may face problems of power devices burning or cracking if something goes mistakinly wrong.

I don't wish to dissuade you from doing anything but based on your level of expertise on this field with regard to this project, you may think appropriately how to go ahead with this design.

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