Designing an inverter transformer can be a complex affair. However, using the various formulas and by taking the help of one practical example shown here, the operations involved finally become very easy.
The present article explains through a practical example the process of applying the various formulas for making an inverter transformer.The various formulas required for designing a transformer has been already discussed in one my previous articles.
Update: A detailed explanation can be also studied in this article: How to Make Transformers
Designing an Inverter Transformer
An inverter is your personal power house, which is able to transform any high current DC source into readily usable AC power, quite similar to the power received from your house AC outlets.
Although inverters are extensively available in the market today, but designing your own customized inverter unit can make you overwhelmingly satisfied and moreover it's great fun.
At Bright Hub I have already published many inverter circuit diagram, ranging from simple to sophisticated sine wave and modified sine wave designs.
However folks keep on asking me regarding formulas that can be easily used for designing a inverter transformer.
The popular demand inspired me to publish one such article dealing comprehensively with transformer design calculations. Although the explanation and the content was up to the mark, quite disappointingly many of you just failed to grasp the procedure.
This prompted me to write this article which includes one example thoroughly illustrating how to use and apply the various steps and formulas while designing your own transformer.
Let’s quickly study the following attached example: Suppose you want to design an inverter transformer for a 120 VA inverter using a 12 Volt automobile battery as the input and need 230 Volts as the output. Now, simply dividing 120 by 12 gives 10 Amps, this becomes the required secondary current.
Want to learn how to design basic inverter circuits?
In the following explanation the Primary Side is referred to as the Transformer side which may be connected at the DC Battery side, while the Secondary side signifies the Output AC 220V side.
The data in hand are:
- Secondary Voltage = 230 Volts,
- Primary Current (Output Current) = 10 Amps.
- Primary Voltage (Output Voltage) = 12-0-12 volts, that is equal to 24 volts.
- Output Frequency = 50 Hz
Calculating Inverter Transformer Voltage, Current, Number of Turns
Step#1: First we need to find the core area CA = 1.152 ×√(24 × 10) = 18 sq.cm where 1.152 is a constant.
We select CRGO as the core material.
Step#2: Calculating Turns per Volt TPV = 1 / (4.44 × 10–4 ×18 × 1.3 × 50) = 1.96, except 18 and 50 all are constants.
Step#3: Calculating Secondary Current = 24 × 10 / 230 × 0.9 (assumed efficiency) = 1.15 Amps,
By matching the above current in Table A we get the approximate Secondary copper wire thickness = 21 SWG.
Therefore the Number of Turns for the Secondary winding is calculated as = 1.96 × 230 = 450
Step#4: Next, Secondary Winding Area becomes = 450 / 137 (from Table A) = 3.27 sq.cm.
Now, the required Primary current is 10 Amps, therefore from Table A we match an equivalent thickness of copper wire = 12 SWG.
Step#5: Calculating Primary Number of Turns = 1.04 (1.96 × 24) = 49. The value 1.04 is included to ensure that a few extra turns are added to the total, to compensate for the winding losses.
Step#6: Calculating Primary Winding Area = 49 / 12.8 (From Table A) = 3.8 Sq.cm.
Therefore, the Total Winding Area Comes to = (3.27 + 3.8) × 1.3 (insulation area added 30%) = 9 sq.cm.
Step#7: Calculating Gross Area we get = 18 / 0.9 = 20 sq.cm.
Step#8: Next, the Tongue Width becomes = √20 = 4.47 cm.
Consulting Table B yet again through the above value we finalize the core type to be 6 (E/I) approximately.
Step#9: Finally the Stack is calculated as = 20 / 4.47 = 4.47 cm
Table A
| SWG | AMP | Turns per Sq.cm |
|---|---|---|
| 10 | 16.6 | 8.7 |
| 11 | 13.638 | 10.4 |
| 12 | 10.961 | 12.8 |
| 13 | 8.579 | 16.1 |
| 14 | 6.487 | 21.5 |
| 15 | 5.254 | 26.8 |
| 16 | 4.151 | 35.2 |
| 17 | 3.178 | 45.4 |
| 18 | 2.335 | 60.8 |
| 19 | 1.622 | 87.4 |
| 20 | 1.313 | 106 |
| 21 | 1.0377 | 137 |
| 22 | 0.7945 | 176 |
| 23 | 0.5838 | 42 |
| 24 | 0.4906 | 286 |
| 25 | 0.4054 | 341 |
| 26 | 0.3284 | 415 |
| 27 | 0.2726 | 504 |
| 28 | 0.2219 | 609 |
| 29 | 0.1874 | 711 |
| 30 | 0.1558 | 881 |
| 31 | 0.1364 | 997 |
| 32 | 0.1182 | 1137 |
| 33 | 0.1013 | 1308 |
| 34 | 0.0858 | 1608 |
| 35 | 0.0715 | 1902 |
| 36 | 0.0586 | 2286 |
| 37 | 0.0469 | 2800 |
| 38 | 0.0365 | 3507 |
| 39 | 0.0274 | 4838 |
| 40 | 0.0233 | 5595 |
| 41 | 0.0197 | 6543 |
| 42 | 0.0162 | 7755 |
| 43 | 0.0131 | 9337 |
| 44 | 0.0104 | 11457 |
| 45 | 0.0079 | 14392 |
| 46 | 0.0059 | 20223 |
| 47 | 0.0041 | 27546 |
| 48 | 0.0026 | 39706 |
| 49 | 0.0015 | 62134 |
| 50 | 0.0010 | 81242 |
Table B
| Type | Tongue Width (cm) | Winding Area (cm²) |
|---|---|---|
| 17 (E/I) | 1.270 | 1.213 |
| 12A (E/12I) | 1.588 | 1.897 |
| 74 (E/I) | 1.748 | 2.284 |
| 23 (E/I) | 1.905 | 2.723 |
| 30 (E/I) | 2.000 | 3.000 |
| 21 (E/I) | 1.588 | 3.329 |
| 31 (E/I) | 2.223 | 3.703 |
| 10 (E/I) | 1.588 | 4.439 |
| 15 (E/I) | 2.540 | 4.839 |
| 33 (E/I) | 2.800 | 5.880 |
| 1 (E/I) | 2.461 | 6.555 |
| 14 (E/I) | 2.540 | 6.555 |
| 11 (E/I) | 1.905 | 7.259 |
| 34 (U/T) | 1.588 | 7.259 |
| 3 (E/I) | 3.175 | 7.562 |
| 9 (U/T) | 2.223 | 7.865 |
| 9A (U/T) | 2.223 | 7.865 |
| 11A (E/I) | 1.905 | 9.072 |
| 4A (E/I) | 3.335 | 10.284 |
| 2 (E/I) | 1.905 | 10.891 |
| 16 (E/I) | 3.810 | 10.891 |
| 5 (E/I) | 3.810 | 12.704 |
| 4AX (U/T) | 2.383 | 13.039 |
| 13 (E/I) | 3.175 | 14.117 |
| 75 (U/T) | 2.540 | 15.324 |
| 4 (E/I) | 2.540 | 15.865 |
| 7 (E/I) | 5.080 | 18.969 |
| 6 (E/I) | 3.810 | 19.356 |
| 35A (U/T) | 3.810 | 39.316 |
| 8 (E/I) | 5.080 | 49.803 |
Questions & Answers
please transformer laminations are very scarce to get, I checked online to purchase for 5Kva, their minimum quantity is in 100kg to 1 tonnes. please sir is there any guide?
Seun, in that case you can consider buying a readymade transformer and rewind it as per the calculations, or go for a ferrite based transformer…
Sir, do you mean ferrite based cores are readily available online easily?
Yes, ferrite cores are easily available and iron core readymade transformers are also available…
Thanks sir. If I want to make the secondary voltage 300v output for the iron core, please how will I calculate the turns.
Thanks Seun
For 300V secondary output, you just have replace all the 230V entries given in the above calculations, with 300V.
please I need a 2000Watt transformer with the following v
alues: Primary:18V-18V,12V center tap, Secondary:600V,230V-0V ,12V-0V
Please can I wind the inverter transformer 350vac? Thanks sir
Yes you can do it..
Hello sir, please how can I use 1 single transformer with secondary output with 8 ends to charge a 4 battery sets in series, 48v. I want to use the trafo to charge the batteries individually not as a whole.
Hello Daniel, What are the voltage and current specifications of the 4 batteries and what are voltage and current specifications of the transformer output wires? Please let me know this, i will try to figure it out.
Thanks sir, Engineer Swatagam, I appreciate. The batteries are lead acid 26ah/12v each, 15v, 3A trafo rating.
output rating of the trafo is 15v, 3amps for each of the secondary windings
Ok, thanks, however, unfortunately if the batteries are connected in series then they cannot be charged directly through aa DC supply, rather it will require an automatic changeover circuit which will detect the low charge levels on each of the batteries and connect the supply to those specific batteries in a sequential manner.
Here’s one example circuit for your reference:
https://www.homemade-circuits.com/lipo-battery-balance-charger-circuit/
Thanks Daniel, ok, but the voltage and current values of each output from the transformer will be also required…
Hi!
I would like to buy a 72V VDC transformer for 72v Li-ion battery to 220VAC on 15kw. Where Output 220VAC 50Hz on 80 Amperes if it can be done, and input VDC 72V with a few Amperes to connect the battery to it. So I need an inverter transformer, capable of powering 2x 4000 watt server computer power supplies that will have 16 Amperes each. Does this transformer work in your opinion? Or should I buy a 220V VDC transformer?.
Hi, If your load is rated to operate at 220V AC 16 amps then your transformer must be able to satisfy this much power, that is all is required from the transformer.
If the primary side of the transformer is 72V, then its current rating must be 4000 / 72 = 56 amps.
Hi! thanks the response!
The batteries Li-ion is 72v 50Ah 150Ah BMS, it work?.
72 * 50 = 3600 watts, which cannot power 2 * 4000 = 8000 watts.
You will need at least a 120 Ah battery, which may provide a backup of not more than 60 minutes.
Hello sir, for experiment purpose, is it possible to build a 80v input transformer to 12v output, Stepdown
Hello Daniel,
Yes that’s possible, you can create a transformer with any voltage ratios, as you like.
If I use double 15awg wire in primary will it work? Current rating will increase?
Yes it will increase the current capacity of the transformer, make sure to upgrade the secondary side also.
Ok. Thanks
Thanks a lot
Please help me, I want to build a 66-84v(72) 1500w, H-bridge inverter, how can I select the quantity of MOSFET to design the inverter, thank you
Hi,
No need of adding MOSFETs in parallel. You can use the following MOSFET, just 4 will be enough for your H-bridge configuration.
https://www.mouser.in/datasheet/2/196/Infineon_IPP045N10N3_G_DataSheet_v02_09_EN-3362488.pdf
Sorry, this MOSFET model PP045N10N3 is not within my reach. I can use some of these serial MOSFET example: Irfp264
Irfp460
Irls4030-7P
Irfp4468
104r5ns
The IRLS4030-7p appears to be the best candidate, you can use four of these in your H-bridge:
https://www.infineon.com/dgdl/irls4030-7ppbf.pdf?fileId=5546d462533600a401535671d8902713
Can I use microwave transformer as inverter transformer?
You can use any transformer for making an inverter as long as its winding matches the required voltage specifications.
Please kindly assist me in producing my mini inverter that can power my home appliances up to 220v in AC.
Please build the 3rd modified sine wave inverter schematic from the following article, which uses MOSFETs. First build and test this, if you succeed then I will tell you how to upgrade it for more power:
https://www.homemade-circuits.com/modified-sine-wave-inverter-circuit-2/
Please I need help I have a toroidal iron core transformer I want to use and design inverter transformer frequency is 50Hz the core dimensions are: OD=16.8cm, ID= 7.6cm and H=10cm how do I calculate the power of the transformer, core area and turn per volt.
Thanks
Sorry, I don’t have the formulas for calculating toroidal transformers…
I’m confuse on inverter transformer and stabilizer transformer my challenge is that can I use stabilizer transformer core to design inverter transformer I have an 8kva stabilizer transformer core ring type can I use it to design inverter transformer of 7.5kva/72v.
Yes, that’s possible, you can use a stabilizer transformer core to design an inverter transformer.
Hello! How much Ampere should I use when using a power inverter that is 1000 watts? Lets say, is it sufficient or safe to use a 30 or 50 amperes of transformer?
The transformer can have any specifications depending on the requirement, it is not an issue. For 50 amp transformer the battery voltage will need to be 1000/50 = 20 V
What do you mean the battery voltage? For example, I have 12-0-12 volts, 1000 watts. So I need my battery would be 24 volts?
The battery that you use for the inverter. For 12-0-12V transformer the battery voltage will be 12V not 24V.
I think in an inverter design the transformer primary voltage should less than the rated battery voltage or the secondary voltage should be little higher than the rated output voltage.
Another thing I want to ask you my brother is:
At what input voltage rating Will a transformer used in a 12volt pure sine wave inverter will be, is’t 7volt or 13-14volt will the transformer input voltage be?
Thanks in advance.
Emmanuel, yes, the transformer primary voltage should be slightly lower than the battery voltage spec.
For a pure sine inverter you will have to measure the gate/source SPWM average voltage of MOSFETs, this will provide you the average value for the transformer primary voltage.
Thanks for your quick response.
Please can you list out the gate to source spawn average voltages and their corresponding voltages to the input voltage rating of the transformer.
Example: for 7volt transformer what will be the gate to source average voltages and so on.
Thanks in advance.
First you will have to build the inverter circuit with SPWM fed across the gate source of the MOSFETs, then manually measure the DC voltage across the base/source of the MOSFETs. This result will be equivalent to the value of the primary voltage of the required transformer.
Thanks for your quick response ????.
If I should get you right, you mean that if I should have 5volt DC in my SPWM circuit as my gate to source spwm average voltages then the transformer primary voltage will be somewhere 5volt to 7volt?
Thanks in advance
I am assuming that you already have a sine wave inverter/oscillator circuit setup with you. In this situation if you measure the gate/source DC voltage of the MOSFETs, that will give you the primary voltage of the transformer.
My gate to source spwm average voltage of the MOSFETs is somewhere 1.1volt to 1.5volt, it varies depends on the load. So what will be my transformer primary voltage?
Please check it without a transformer. If still it shows 1.5 V then something’s wrong with your SPWM generator, it cannot be so low….it should be around 4 to 6 v for a 12V battery.
Yes is still 1.5volt without transformer connected to it.
I’m designing the configuration of a PWM to SPWM CIRCUIT type of oscillator circuit that you shown in your other post. When the oscillator is on PWM mode (that is without attaching the other high frequency PWM circuit that will break down the low frequency PWM), i do have 4.8volt in my gate to source voltage but when I attach the high frequency PWM circuit, it brings down the gate to source spwm voltage to about 1.5volt.
So could it be that I need to boost the gate to source spwm average voltages with an amplifier stage driver?
Thanks in advance.
Yes that is the design that I used.
But I don’t have oscilloscope to confirm the waveform of my SPWM generator.
What i really want to understand is that if i should get 6v at my MOSFETs gate/source terminal it means that my transformer will be 6v 0 6v in it primary and the secondary will be 230v?
Yes that is correct….but without an oscilloscope a sine wave inverter cannot be built.
I guess you have used the concept explained in the following article.
https://www.homemade-circuits.com/designing-a-sine-wave-inverter-circuit-from-the-scratch-tutorial/
In that case you will have to confirm the SPWM waveform with an oscilloscope, without an oscilloscope it can be impossible to know what is causing the SPWM to drop to 1.5V.
You can also check the SPWM average DC voltage directly across the op amp output, ad see whether it is 1.5V or not. In any case an oscilloscope will be required.
https://www.homemade-circuits.com/dso138-best-small-oscilloscope-for-electronic-hobbyists/
It is very helpful
Hello Swagtam. Please can I get the full table A and B chart. I need a current rating for 30Amps wire.
Hello Simon,
Unfortunately the tables are limited to 10 amp current only, and I do not have the data for currents above 10 amp.
OK sir. Thanks for your prompt reply. Can I still use the values in my calculation without the Primary Winding Area?
No problem Simon, but I don’t think the transformer can be completed without the primary winding area, so that may not be possible.
Please what guage for small step down transformer should I use for AC supply of 110v 50mA,
You can calculate it as per the formulas provided in the following article:
https://www.homemade-circuits.com/how-to-make-transformers/
Greetings Swagatam, thanks for your informative site. Where the transformer is the load in a H bridge inverter circuit and the DC is a 12volt battery, what should the primary winding voltage be? The inverter is a 1000w 220v output and all the mosfets are blown.
Thanks Ben, the transformer primary winding can be 0-12V, but preferably it should be slightly less, around 0-9V.
Please sir, for knowledge reason, why is 0-9v is preferable. Thanks.
Hi Seun, The transformer voltage must be slightly lower than the battery voltage to compensate the battery low voltage conditions. Suppose a 12V transformer produces 220V when the battery is 13V, then if the battery voltage drops to 11V, the inverter voltage would proportionately drop to 186V which is not good…this issue is avoided by using a relatively lower voltage transformer.
Thanks Swagatam, I am grateful. Please explain when it is 9v transformer, how it plays out.
Hi Seun,
As a rule of thumb you can use a 9V transformer when the inverter is a 50% square wave inverter with a 12V battery. For a PWM inverter you may have to check the average DC the PWM generates, which can be used to determine the primary voltage spec of the inverter
Pls can u recommend any textbook about dese transformer equations u used.
Yo can search it online you may many find good options.
Okay tnks a lot
Hi, I can’t calculate this: “First we need to find the core area CA = 1.152 ×√ 24 × 10 = 18 sq.cm”
For me the result is = 56,463
Hi, thanks for pointing out the mistake in the formula, please check it now. The square root is for 24 x 10 combined.
It seems to be correct
sir please how can i use 5kva stabilizer transformer as a center tap transformer for my inverter
You can use it, it will work only as long as the center tap winding specifications matches the battery and the circuit output specifications.
please sir how can i identify the primary side of 5kva stabilizer transformer
use a series 40 watt bulb and feed a 220V AC randomly across the unknown wires. For the 220V wires the 40 watt bulb illumination should be minimum or almost zero.
sir can irf3205 two on each channel with 12v 100ah battery drive 5kva stabilizer transformer
It will drive the transformer, but the output will be 200 watts max.
Input&Output, Primary&Secondary depend on the ‘function’ the transformer (tr) is performing:
Inverter/Step-up (I) mode Or Battery Charging/Step-down mode (C).
Normally, Primary refers to Input side, while secondary refers to Output side.
The data in hand are:
Secondary Voltage = 230 Volts,
Primary Current (Output Current) = 10 Amps.
Primary Voltage (Output Voltage) = 12-0-12 volts, that is equal to 24 volts.
Output Frequency = 50 Hz
In the above, the Inverter mode is assumed, so Secondary/Output = 230 Volts.
Then primary I, and V should be Input and not Output, IMO.
Though understood, better to include a #Definition/assumption statement – Inverter Mode.
Hello,
Googled and located your site. Gr8 design info on how to build an inverter from scratch. I did BE EEE 40 years back, don’t remember any theory now, nor practically worked on inverter or any other circuit design.
Here is my silly basic query:
My old squarewave 750VA, 24V (2*12v battery in series) inverter’s MOSFETs burnt.
I think the copper transformer is intact.
I want to use the transformer and convert it to a 12V sinewave inverter, by replacing both the existing boards.
Is it possible?
If yes, where can I buy the rquired switching circuit board.
Thanks
Thank you for visiting my site, glad you liked the design and the content of this site!
Yes that’s possible…I think if you search online the phrase “sinewave inverter module” you should be able to get the right circuit board for your application.
The board should be available in amazon and other similar online shopping sites.
thanks for your quick response, i found couple of boards for 12v system.
however these boards do not specify the transformer specs
so what I am still not sure is, will it work with the existing transformer, which is wound for 24v?
will the primary ( dc volt side) windings be not different?
just want to make sure before I buy it.
Are you referring to EGS002 module? The transformer primary is supposed to be connected between the external mosfet bridge circuit. The transformer primary voltage will depend on the battery used. Yes a 24V transformer can e used, and will require a 24V battery to operate the external mosfet stgae with the tramsformer.
Following few search results.
Indiamart.com
1. Su kam sine wave inverter board 12 volt 900va from 1500/-
Amazon.in
1. RASHRI ; One For All Su-kam Pure Sinewave 900KV Inverter kit, 900VA Inverter Board, PCB, Inverter Motherboard 1948/- (same as indiamart?)
2. Rashri Su-kam 1000 watt Pure sinewave Inverter Board, Motherboard, PCB 2279/-
3. Alam 12V Sinewave Inverter Board Upto 1000VA (Suitable for All Sinewave Inverter) 2600/-
and many more 12V boards, including boards for Luminous and Microtek inverters.
Put it other way, a 12V system board will NOT work if connected to a 24V transformer, right?
beacuse, a 12V system requires 12-0-12 transformer, 24V needs 24-0-24 and my existing 24V transformer is likely to be 24-0-24.
And how much VA depends on transformer windings, thats secondary. I can choose a board with highest VA that the transformer can support.
When I search, I specifically get the EGS002 board based results, and is the recommended one according to me.
The 12V board will work for 24 V or any other voltage also since the 24v will be used across the MOSFET bridge, while the 12V will be used to power the circuit board.
The transformer VA will depend on the MOSFET rating and the battery capacity.
I scratched my head yesterday, and few more strands of hair fell down on my already bald head :).
But I recollected RMS, Peak V, Half, Full, Bridge rectifiers …
My requirement: Use my existing 24V system transformer, with a new 12V pure sinewave inverter board with 12V battery.
I dont agree – “The 12V board will work for 24 V or any other voltage also since the 24v will be used across the MOSFET bridge, while the 12V will be used to power the circuit board.”
There is only one 12V battery, where is 24V?
The eg you have given assumes a 24V battery system, with 10A ( I or O?) current; which results in certain no of windings, gauge etc.
For a 12V system, all these will be different, especially primay windings.
I have a transformer that is for a 24V system, and the circuit is accordingly designed.
For a 12V system, no of primary windings should be double?
In the Inverter Mode, Primary PCM 24V DC input is stepped up to 230V AC secondary output.
If I connect a 12V inverter board to my transformer, it may give perhaps 110V AC?
Not sure what rectifier (full or bridge) is used in all these inverter boards.
In the Charging Mode, my transf with Full wave rectifier will give 24V DC, damaging the 12V battery.
Assuming my transf is center-tapped 12-0-12, I can use 12-0 leads with a custom-made inverter board with a bridge rectifier for charging.
Or modify the charging circuit in the off-the-shelf 12V inverter board by converting Full to Bridge wave rectifier.
But if its not center-tapped, it cannot be used.
Please correct my understanding.
You can check the following circuit diagram. Here you can the mosfet bridge is supplied from an external voltage source which can 12V, 24V, 48 V etc
But I am not sure whether the EGS002 has a charging system or not?
Thanks.
I got this:
1000W DC 12V 24V To AC 110V 220V 380V High Frequency Power Inverter Board Car Converter
AIO board – switching, control & transformer.
Supposed to have a provision to connect a 12/24/48v battery – good.
Though 1000W, says Car Converter- cannot be used as home inverter.
And in $ from China, and squarewave. But gives a good design idea.
My faulty inverter has separate control and switching boards.
– gives the flexibility to choose a switching board of the required VA.
– maybe less costly to service, as only one of the 2 boards needs repair/replacement.
In my case, I need to replace the burnt switching board only.
OK, if it suits your needs you can use it, no problems!
I searched for 12 v pure sinewave inverter board, EGS002 does not showup always.
But if I search for 12V pure sinewave inverter board and click View all, EGS002 shows up.
Forget about Google’s targetted/preferential … search results.
The description says … Inverter Module, EGS002 is a driver board …
SKU: 896558
1. 5V single power supply – for what?
..
It does not talk about what Ah, V, battery is supported to provide 230V ac, nor the transformer specs.
Most important, figure does not show Mosfets mounted on big heat sinks, or transformer.
I feel it is just a ‘driver/pre-processor’ board. IMO, the ones I have listed is what is needed.
Yes it is a driver board.
The 5 V is probably the operating voltage for the driver microcontroller circuit.
The power mosfets, and transformer needs to be configured externally and integrated with this driver board, which gives you the freedom to upgrade the inverter power to any desired levels. You can refer to this article to learn more regarding how to upgrade the battery, trafo and mosfets appropriately.
https://www.homemade-circuits.com/how-to-calculate-and-match-inverter/
How to make 1250VA 1000 watt 260v _12v ups transformer ?
Good day Sir, please what wire gauges for 2.5kva primary and secondary?
I used gauge 13 whose amp capacity is 8.6 but while charging the 16amps Circuitbreaker trip off until I used 25amps breaker, why?
Hi Seun, sorry I am not sure about that, because there’s no way I can calculate the wire gauge of a 2.5kva transformer.
Good day Sir, please I want to learn how I can wind a transformer coil with secondary coil connected to another joule thief transformer
Hi Seun, sorry, presently I do not have the details regarding the question that you have asked.
Or any link or guide
Can the above core area, turns per volt formula work extremely well with ordinary iron core transformer?
Yes, the formulas are for the ordinary iron core transformer.