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## Simple Induction Heater Circuit - Hot Plate Cooker Circuit

The proposed induction heater circuit exhibits the use of high frequency magnetic induction principles for generating substantial magnitude of heat over a small specified radius.

The discussed induction cooker circuit is truly simple and uses just a few active and passive ordinary components for the required actions.

Update:

Learn how to design your own customized induction heater cooktop:

Designing an Induction Heater Circuit - Tutorial

Induction Heater LC Resonance Frequency and Current

According to the involved principle when a change in magnetic field is forced around a metal, electrons inside the metals get agitated and begins flowing across the metal, this is termed as eddy current. This flow of current in the metal or the introduced conductor causes a heat to be generated in the metal making it warmer.
The generated heat is proportional to (current)^2 x resistance of the metal.

The above heat is also directly proportional to the induced frequency and that's why ordinary iron stamped transformers are not used in high frequency switching applications, instead ferrite materials are used as cores.

However here the above drawback is exploited for acquiring heat from high frequency magnetic induction.

Referring to the proposed induction heater circuit below, we find the concept utilizing the ZVS or zero voltage switching technology for the required triggering of the mosfets. The technology ensures minimum heating of the devices making the operation very efficient and effective.
Further to add, the circuit being self resonant by nature automatically gets sets at the resonant frequency of the attached coil and capacitor quite identical to a tank circuit.

The circuit fundamentally makes use of a Royer oscillator which is marked by simplicity and self resonant operating principle. However the main downside of the design is that it employs a center tapped coil as the transformer, which makes the winding implementation a bit trickier. However the center tap allows an efficient push pull effect over the coil through just a couple of active devices such as mosfets.

As can be seen, there are fast recovery or high speed switching diodes connected across the gate/source of each mosfet. These diodes perform the important function of discharging the gate capacitance of the respective mosfets during their non-conducting states thereby making the switching operation snappy and quick.

You can use IRF540 as the mosfets which are rated at good 110V, 33amps. Heatsinks could be used for them, although the heat generated is not to any worrying level, yet still it's better to reinforce them on heat absorbing metals.

The inductor L2 terminating from center of the main induction coil is a kind of choke for eliminating any possible entry of the high frequency content into the power supply and also for restricting the current to safe limits.

Relatively the value of L2 should be high enough, a 2mH will do the job well. However it must be built using high gauge wires for enabling high current usage through it safely.

C1 and L1 constitute the tank circuit here for the interned high resonant frequency latching. Again these too musts be rated to withstand high magnitudes of current and heat.

Here we can see the incorporation of a 330nF/400V metalized PP capacitors.

Now comes L1, which is the most crucial element of the whole circuit. It must be built using extremely thick copper wires so that it sustains the high temperatures during the induction operations.
The capacitor as discussed above must be ideally connected as close as possible to the L1 terminals. his is important for sustaining the resonant frequency at the specified 200kHz frequency.

For the induction heater coil L1, many 1mm copper wire may be wound in parallel or in bifilar manner in order to dissipate current more effectively causing lower heat generation in the coil. Even after this the coil could be subjected to extreme heats, and could get deformed due to it therefore an alternative method of winding it may be tried.

In this method we wind it in the form of two separate coils joined at the center for acquiring the required center tap.

In this method lesser turns may be tried for reducing the impedance of  the coil and in turn increase its current handling capability. The capacitance for this arrangement may be in contrast increased in order to pull down the resonant frequency proportionately.
In all 330nF x 6 could be used for acquiring a net 2uF capacitance approximately.

The following image shows the precise method of attaching the capacitors in parallel with the end termianals of the copper coil, preferably through a well dimensioned PCB.

Parts list for the above induction heater circuit or induction hot plate circuit

R1, R2 = 330 ohms 1/2 watt
D1, D2 = FR107 or BA159
T1, T2 = IRF540
C1 = 10,000uF/25V
C2 = 2uF/400V made by attaching 6nos 330nF/400V caps in parallel
D3----D6 = 25 amp diodes
IC1 = 7812

L1 = 2mm brass pipe wound as shown in the following pics, the diameter can be anywhere near 30mm (internal diameter of the coils)

L2 = 2mH choke made by winding 2mm magnet wire on any suitable ferrite rod

TR1 = 0-15V/20amps

POWER SUPPLY: Use regulated 15V 20 amp DC power supply.

Using BC547 transistors in place of high speed diodes

In the above induction heater circuit diagram we can see the mosfets gates consisting of fast recovery diodes, which might be difficult to obtain in some parts of the country.

A simple alternative to this may be in the form of  BC547 transistors connected instead of the diodes as shown in the following diagarm.

The transistors would perform the same function as the diodes since the BC547 can operate well around 1Mhz frequencies.

•  Stumble

1. Dear sir which diode can i put in place of FR107

1. You can use BC547 transistor in place of the diodes. Connect base and collector together with the gate of the mosfet, and emitter to the drain of the other mosfet.

2. can i take L1 from another induction cooker ?

1. No, only the specified type will work.

2. Hello sir can I use it for boiling a moving water from pipe.

3. Helo Salman,

Yes you can do it, but the pipe should be made of iron or steel (magnetic material)

4. Thank you for the quick response,
So pipe that Water flow inside, is a metal to be heated or as a induction metal(L1)?

5. The iron water pipe should pass through the center of the coil L1 as shown in the last diagram.

6. Hi sir. Can I use this system to make an induction sealer. Is this enough to seal aluminum foil lid with plastic cup.

7. Hi Asanthan, that may be possible, however for sealing plastic, ordinary heater coil would be much hassle-free and efficient.

3. so do I calculate the power using the formula: VOLTAGE X CURRENT?

4. Not worked swgtm. the material not even heat up & both mosfets burnt out. it specified 200kHz frequency. So can i use Astable multivibrator to set frequency 200Khz to drive the coils.

1. Hi Max,

What did you use for D1/D2 and L2?

2. FR302 & 40 turns on a ferrite bead as L2

5. hello swagatam.
Plz suggest a circuit to run cooling fan externally. i bought a amplifier unit the heat sense fan stops automatically after 1 minute. need a solid state cheap circuit to run fan directly from mains. (fan rated 12vdc 0.25amp 2.5w)

1. Hello Max,

The only solution is to a use a readymade 12V ac/dc smps adapter rated at 500mA or 1amp current, because you won't get below this rating.

6. Hello Swagatam,
I have built my one successfully with DC power source of 18V connected to L2 while the other side keep 12V to drive MOSFET. I am also connecting ammerter in series to L2 to monitor the current. With some bolts and nuts or steel rod. They can turn red hot without problem. Current goes up from original L1 coil without anything inside to some level according to the object inside the coil. Somehow, I try this with 1/2" diameter steel pipe with 0.5mm thickness. Current goes up and increasing. After a while when pipe is in red hot, current suddenly increase very rapidly and FET burn-out. At this point, everything stop. I have to change FET as it was shorted Drain-Source. I used IRFP250N and diode BYV26E, pretty high rated voltage and current but still failed. Do you have any idea what I did wrong? Is this due to FET or Diode? Thanks.

1. Helo Sitti,

Try the following circuit, set Rt, Ct for getting 200khz, use L2 in place of "L" and the L1 for RL.

This circuit will never allow your mosfets to blow off, according to me.

7. Is there any alternative power supply? Cause its too expensive to buy a 20 A transformer then make it DC supply. By the way, could I use a power supply with adjuster in order to control the temparature of the induction coil?

1. sorry there's no direct alternative for high current. You can reduce it proportionately by increasing the voltage, but that would also require modifications in the work coil, the turns will need to be increased while the gauge will need to reduced accordingly.

2. thanks for the quick reply, I really want to learn more about induction heating. Where I can find a choke coil required L2 because I can't find one of it in some electronics store here in my place, is it okay not to put L2? I want to share my idea to you, I have a circuit design that I found in the internet to control temperature, how can I share it to you?

3. You won't get the coils readymade, you will have to hand make it as per the details shown in the images and the article info.

You are welcome to share your ideas, please send it to hitman2008@live.in

4. can we use the psu of computer

8. is it safe that my transformer that is rated 6A only is giving me up to 10A of current. Because i connected it to a bridge rectifier and a 4700uF caps to make a dc power supply, then i successfully make the circuit work but when I measured the current flowing to the transformer using a clamp meter, it gives me up to 10A depending on the metal to be heated. is it still safe for the transformer producing greater current than its rating?

1. if it's showing more than the specified amps of the transformer means the voltage is being dropped proportionately in the course....so ultimately the total power is never being exceeded.

as far as the above circuit is concerned, the coil would handle current depending upon its thickness, if it's correctly dimensioned it would be safe.

9. sir supply is 300w or 15v 20a ?

1. It's 15V/20amp, that's equal to 300 watts

2. sir, i mean can i use 150v 2amp?

3. no, it should be @15V, amps is not important can be of any value (not less than 20amps)

4. Sir, both terminal will be +ve? if yes then; where is -ve terminal? And in MOSFET source will be grounded or -ve?

5. only the mosfet sources will go to the negative of the supply, no other point of the circuit is connected to the supply negative.

6. Sir, this kind of power supply(15v, 20a)is not esily available in the market.So, at which minimum voltage and current the circuit will be run?

7. Vinay, you can use a 12V, 20 amp transformer

10. Hello Swatam
what changes I should make in the circuit to operate at 220V , two phases, each 110 V and a power of 6kW.
and I'm thinking to cool L1 and L2 with water that circulates inside
this is possible.

1. Hello Paul,

Sorry, I think that may not be recommended and could require more number of turns for L1/L2...I do not have the data for calculating those.

11. thank you very much.
the number of turns can prove, but the electronic elements can recommend me what changes should be do.

1. The configuration will remain as is. The resistors could be increased to 1K 10 watt (wirewound) each, everything will need to be done through trial and error, though.

For the mosfets you can use IRF840, however since mains voltage is involved, the risks of an untoward could be on the cards, I am not recommending use of 220V for this project.

12. i have built one successfully but my capacitors tanks become very hot....
i am using parallel cap at single point and where the all cap meet(at single point) they get very hot.
should i mount capacitors on pipes at some distance?

1. yes preferably the caps must be p;aced slightly away from the coil, may be a 6 inches distance will do.

13. One more thing
At the start current go up very high without anything inside..

1. you can use a 1000 watt halogen lamp in series with the mains input to the transformer, this will ensure that the initial amp intake does not exceed to dangerous levels.

14. Thanks Swagatam
I made my induction heater successfully now i want to increase its power..
Can i increase power of this induction heater using more mosfets in parallel?
Please scheme a circuit for parallel combination.
Thanks

1. Thanks Waqar, to increase power you may try increasing the input current and also the voltage, and upgrade the mosfet with other higher rated ones, parallel combination may not be recommended.

You can select an appropriate mosfet pair from the following article

http://easydatasheets.blogspot.in/p/mosfets.html

15. Can i pass the iron or steel tube(from which water which is to be heated) three to four times from the coil L1.

1. it should be a copper coil, iron will not do.

16. sir we are making induction heater ckt for academic project purpose so could u tell us about the length and turns of L1,L2

1. you can find it in this video: https://www.youtube.com/watch?v=pVYMLnXW9uo

17. can i use a high rated transformer and then minimize the current and voltage by a rheostat.

1. you may have to do it through a variac, a rheostat will not do.

2. ty sir.
can i fed the circuit with directly 20 amp or i have to increase it gradually because the insulation of my wire which are use for connection are burning along with mosfet.
what is the reason for the same

3. increase it gradually, but if the mosfets are also burning it means the circuit is malfunctioning and there could be a fault in the circuit

4. sir plz help me out.
when i increase the voltage with the variac my bridge rectifier burned out at 7 volt and if i fed the circuit directly my mosfet burned out.
what should i do..

5. Pratik, it means the circuit is drawing huge currents without load, something is incorrect in your circuit.

try a bridge driver type of circuit instead of the above self resonanat design for reliable results

6. Hello sir,
Can we control the temperature of this circuit and can we use small lcd for viewing temperature.

18. K..
I'LL CHECK IT OUT

19. Dear Swagatam, thank you very much for the details of the construction of this circuit. I built the heater and works well. I have a question related to the possibility to change the frequency of the system. I need differents frequencies. And I am thinking of if possible to change Capacitor and L at the same time to get any frequency. This is possible? Like for example 200Khz , 300 Khz, 400 and soon.
Also I would know how I can calculate the magnetic intensity of the system.
Thank you very much.

1. Thanks Guillermo, the above circuit is a self resonant type of configuration so frequency cannot be changed manually....you may have to incorporate an external oscillator circuit for implementing an adjustable resonance, the following half bridge circuit could tried with the coil network explained in the above article for achieving the same:

20. Thank You again, i will try the this circuit and let You knoe my progress. Cheers

21. dear sir I have a old induction heater coil . i want to use that coil . how can i use that coil for heat the panel. please tell me with using simple words. thank you...,...

1. Dear Kamaljeet, without seeing the coil it would be difficult to suggest anything, anyway a commercial induction coil will require a sophisticated circuitry, much complex than the above published design...

22. sir
L1 copper wire gauge # kia hay

1. L1 should be preferably a copper pipe having a outer diameter of about 1cm, using a pipe will enable water to be circulated through it in order to keep the coil temp within limits

kia ma ap ko urdu ma b question kr sakta hun

3. yes, but my replies will be in English.

23. hello
what is the exact use of transformer? it is impedance matching only? what can we use instead of transformer

1. which transformer...TR1?

It's for supplying power to the circuit.

24. Hello sir,
what power has to be given to heat a coil?

1. hello jayalaxmi,
the power specs are approximately 20V 15amps

2. Sir,
Cant we heat the coil with Dc source using driver circuit??

I did an oscillator circuit of a supply of 24Vdc and 0.3A and got an output of 46MHz and 19v as peak to peak voltage.
Can we heat the coil with that frequency ?? what are the possible ways??

3. Jayalaxmi, the coil is not supposed to heat, the vessel is supposed to get hot.

0.3A will not produce any result...it should be at least 10 to 15 ampere

25. Hi there,

Its a very nice technology. Thanks for the circuit.
What is the value of L1 and can i use pan cake coil of the same inductance?

1. The inductance value is not crucial, you can make it as per the given instructions in the diagram, yes with little modifications it can be converted for the pan type implementation.

26. Hey, great thread. I was wondering what changes would need to be made to the schematic and the induction coil to work using 3.7vdc max 30amp load. This would obviously be used in a micro induction coil to heat small objects such as a sewing needle. And suggestion on coil size, wrapping and component change on the schematic would be greatly appreciated.
Thanks!
Dan

1. thanks Dan, I think it may have to be done through some trial and error since I do not have a formula for calculating the coil.

The only thing I know is that as the turns increase and the diameter decrease the operating frequency and the current consumption also decrease proportionately, so on this basis you could probably do some experimentation.

L2 and the other components except the voltage may not require a change as per my knowledge

2. hi sir...we try the circuit using the power supply of the computer as the power supply to the circuit....in our first try....the metal that we put on the middle of the working coil gets hot....but the mosfets gets hot too.....so we decided to change the heatsink with bigger one......after changing we try it again.......and the metal dont get hot......why is it happen sir??thanks for the reply

3. Hi Christian, I guess this could be related to some frequency variations due to the introduction/removel of the metal plate.

heating up of the msgfets might be hampering the generation of the resonance frequency which might be getting corrected with the addition of the larger hetasink and resulting in an automatic correction of the frequency.

Not sure though, this could be the reason.

by the way you are not supposed to put a metal inside the working coil, this might seriously affect the functioning of the circuit

4. but, is it ok that we use a power supply of a computer as the supply for this circuit?

what could you suggest sir for us to make this induction warmer work.?

5. I'm sorry sir... the metal that we put inside the working is a screw driver just to test if it is working already,if the working coil produce induction heat
.

6. oh... that was quite silly of me, I completely forgot that a metal (magnetic) needs to be inserted inside the work coil for implementing the design, make sure the heatsinks are perfectly aloof and are not touching anything in the circuit....

any power supply will do as long as it's able to generate 15 to 20 amps for the circuit.

7. good day sir.....in the 2 small diagram above.....the c1 and c2 are in different position...which capacitor do we need to parallel in the l1?

8. we use a power supply of a computer....if we use the bridge driver type circuit...do we still needed to parallel a capacitor with the + and - of the power supply??

9. C1 value needs to be arranged by putting many MKT capacitors in parallel.

If you are using a pure DC from an SMPS in that case C2 can be eliminated....

10. ....I am referring to C1 which is in parallel with L1, and C2 at the bridge...

27. sir may iuse it to cooking purpose

1. It won't be possible with the shown coil dimension

28. am working on this circuit from last few weeks but its not working as i expect it too. am using a coil of 12 gauge 9 turns center taped mosfet irfz44n ,22uf 4 caps in parallel adn the voltage suply is 15 v 12 amps its from a transformer ( battery charger) as i turn on the circuit the the mosfets blows up within seconds seeps like shor circuted help pe am not using any choke .

29. am working on this circuit from few weeks and am facing the same proble as soon as i turn on the supply the current increses upto 40-70 amps and the mosfets blows up . am using irfz44n and 17v 10 amps power supplt from a transformer( its basically a battery charger) am not using any choke please help me out, ? :(

1. the choke (L2) is specifically introduced to limit current and to optimize resonance frequency, if you remove it the circuit is bound to fry immediately.

30. Hello,

My application requires that the object being heated (will be very thin) can be inserted and removed through the side of the coil, as both ends of that object will be fixed and unable to be pulled through the center of the coil. Are you able to tell me if there is any way to construct this without a completely closed heating coil (i.e. with a C-like cross-section instead of an O-shaped cross-section) to allow for side entry of a thin (~2mm diameter) object?

1. Hello, I don't think that's feasible, one method could be by creating a flat spiral coil and then by introducing the object close to the surface of the spiral.

An example spiral coil image may be witnessed in the third diagram below:

31. Hello! Very intersting article!! But i need some help! Can you give me specific models for the D3-D5 (rectifier diodes), C1 capacitor & IC1 on the 1st circuit ?? Ampseres/volts for the IC1 voltage regulator??

1. Hi thanks, D3---D6 can be any rectifier diode capable of handling 25amp current, you can inquire about it with your local component dealer, he will know better and will guide you with the correct number.

32. Ok! Something else...the Maximum DC current for the L2 (1st circuit) it's critical?? Let's say that we have a choke with Max. DC current 15A...it will be ok?? Or we need a higher value?

1. if 15amp is the breakdown limit of the choke then it will not do, if it's the optimal rating then it won't be a problem.

I think the choke wire should be at least 2mm thick or made by using 2 strands of 1mm wire to be able to withstand 15amps

33. i not get o/p plz i can't get output in proteou7s plz help me

34. i cant get output in proteous

1. sorry can't figure out the issue...

2. plz let me know that which circuit diagram is right . as i run both but not working a single and i used 12v,10A supply .

3. i used cooker capacitor of 2uf instead of 330nf ,6pcs how much turns in coil L2 .

4. both the circuits are correct, but the first one is better recommended.

there are many related youtube videos, you can refer any of those for a detailed help.

5. coil which generate heat is either l2 or l1 and how many turns are there for heat coil.

6. let me know about the frequency of this as i want to calculate value of inductor

7. L1 is the heating coil...

details are given in the article

8. frequency can be upto 120kHz

9. let me know about the l1 coil turns and i have to use same wire or other bcoz temporary i used different copper wire and let me know that can ckt run on 12v 10a

10. i want to ask you that either this circuit is run in PROTEOUS 7 simulator becoz i m not getting output in that as well as in real time circuit

11. I have updated the coil data in the parts list.

I have no idea regarding the simulation details, however the circuit has been already tested practically successfully with no issues whatsoever

12. hey swagatam i would like to thank you for updates but how many wound i have to take for
l1 and directly can i use 12v 10a power supply last question is iff i use ditto component then i get output otherwise no t

13. becoz i m not getting heat

14. as you can see in the image, L1 consists of two separate coils made by curling two turns each of brass pipes and then then by joining the center together.....so total it becomes 4 turns, but you can try 3 turns each to make 6 turns.

power supply should be 15V minimum and 15 amps

please check the youtube videos you'll able to see these circuits in real and how these are configured and tested to produce heat.

35. My requirement is heating water ,approx 170ml, upto 90○C. Would it be possible using above circuit?
If not what changes are required? Also would it be possible to run the above circuit on battery power?

1. yes, the above circuit can be used for the purpose.

2. Thanks for the swift reply.

36. plz send me video link

37. what about using 1n4148 or uf4007...which diodes would be better in this circuit?

1. only the recommended ones will work...or any other "fast recovery" type.

38. What is IC 1?

39. Hi

I have put a similar induction coil in a range cooker, instead of a circular cast iron hotplate, I have a circular plate glass sitting in the old hotplate recess with the induction coil underneath, will the all the cast iron in the cooker top affect the induction unit.
It worked for a while but now I am receiving an E0 error on the control panel, but I am going to switch to manual control, Potenimeter I think? would this help Thanks.

Regards Denis.

1. Hi,

sorry, I could not understand your question, do you mean you used a glass instead of cast iron and you are wondering if that would affect the results, then probably the answer is yes, if the cooker is a non-magnetic thing it won't react with the coil's magnetic induction and won't heat up.

where do you intend to use the potentiometer?

40. I need your help to design a working induction heater model for my son studying in 8th standard

would like to get some details on exact materials and design

ramakrishnan

9821075029

1. bill of material is provided in the article

if you follow everything exactly as suggested, you could make it work successfully without much effort.

however this project can be quite difficult for a school student.. as it might involve many complex measurements, adjustments and other related procedures

41. helo sir! my name is biniyam i'm from east africa, ethiopia,i'm universiity student
i sincerly ask u to help me om my semister project which is to replace "enjera"(which is staple food in ethiopia) making stove with induction cooking system

1. Hello Biniyam, You can try the above explained concept first, if you succeed then we can appropriately modify this into a cooker kind of heating system.

42. Hi, before I attempt to build this, what do you estimate as the total cost to build it?

1. could be around \$30

43. Hello sir i make this circuits but not succed.
I use mosfet irfp250
Capasitor csd mer 165j400v
470ohm 2w resistor
12v 1w zea diod
Diod 4100e
10k 1/4w resistor
Induction coill old pc power suply
I use 24vdc 14amp power suply
I make heting coill 9 trun copartube 7mm.coill diametar 1.5"
So what is tha miss take.pless helf me

1. hello Saiful, where did you use the zener diode, if you used it for the 7812 it might have got burnt and shorted, make sure you use a 7812 IC as shown in the first diagram and not a zener diode....
if you use a 12V/15amp transformer you can get rid of the 7812.

44. Hi know i am succdd
Thanks
But i like make coker heater
How to make coil ?

45. hii im onkar ,
i have made circuit using irfz44n ,diodes=1n5819
and used the power supply of 24v/10amp. with lm7812cv as vr,also i used 2x.47 uf capacitors
but when i start the supply my rectifer and choke coil gets too hot.and circuit does not work at all..
what would be the problem ??pls reply me sir...

1. Onkar, it will be difficult to troubleshoot because I do not know what mistake you might have made in it.

L2 is around 2mH...did you verify this inductance value?

initially use a 200 watt bulb in series with transformer primary, and check whether the coil produces heat or not....

the work coil needs to be built exactly as shown in the above figure, and same is true for the capacitor bank

you can check a few you tube videos on this subject and see how it's is implemented practically...

46. thank you sir for replying,
is it important to have the choke of 2mh value..what will happen if my value is low

1. it is a recommended value....it can be a matter of some trial and error when the final working circuit is built

2. lower values can affect the circuit functioning...

47. Dear Swagatam,

can i make this for smaller diameter of induction coil as small as 5 mm to 1 cm wide to heating a small wire? i need it for an experiment for microbiological purpose...

thank you

1. Dear Prasetyo, the above design is a self resonating kind of circuit so I am not sure whether a coil with a different dimension would automatically adjust with it...or what necessary modifications might be required.

you can try though by changing the L2 specs also, through experimentation

48. hi Swagatam, Thank you for The circuit. I have a question and a clue. I want to measure the magnetic field in the working coil. As the frequency is higth, i don't know how to measure. Could you help me ? How Many tesla or mili tesla. can produce. (B) it is possible to measure or calculated. Thank you in advance

1. Hi Guillermo, I do not have this circuit at the moment but will to include it soon, if it's possible for me.

49. Dear sir
im using index sun pijeon rapido my problem is contin.. sart bip sound and disply no 3 back on wrong side so please solve my problem

1. sorry it will be difficult for me troubleshoot without seeing it practically.

50. Hi, Have you ever done or thought to a circuit relevant an induction heater with a function generator as a controller?
The sense of this request is that I wish to build an induction cooker circuit with the possibilities to verify the frequency value, through my function generator I’m able to achieve a few KHz to a few MHz; my problem is How can I feed the cooker coil without a sort of amplifier? The power after function generator isn't sufficient to feed the coil. In other terms I wish to implement this: Function Generator -> Electronic -> Cooker Coil. Have you got any idea?

1. Hi, I have a similar one circuit in this website you can see it below:

but without a current amplifier driving the work coil is not possible, therefore power devices will be required for generating the specified amount of heat from the coil.

51. can i use 24 v 10 amp smps as power supply?

1. yes can be tried

52. Hi sir,
I m use 17volt 25 amp tranform, is that work? If yes,tell me what the perfect inner and outer dimension of L1? If not, plz tell me what i do?

Sir,
The ICE give me 20 dc to input cct, is that successful for run cct? If not, plz tell me what i do?

Sir,
In our stor is difficult to find L2, can u tell me the dimension of it(L2 mean), and what the value of current and voltage flow in L2?

THANKS SIR

1. Hi, yes 17V, 25 amp will do.

L2 will need to be built by winding 22 SWG enameled copper wire until you reach a 2mH value. the current could be around 10 to 20 amps through L2
there are some good videos in Youtube which you can see for a clearer view of the procedures.

53. Hi again sir..

Can i use 2.64mh with 25 volt and 25amp

1. Initially you should try with a lower voltage may be around 12V, if everything goes well then you can increase it to higher levels for acquiring higher heating ranges.

54. Can I use a pancake coil in L1????

1. yes, it can be tried....

55. Hi sir
It working successfully.
,, sir,, how i cam calculate mathematical representations of current,voltage and frequency?

Thank again sir.

1. Hi, I am glad you could succeed with the above project, but I am sorry I am not entirely sure about the mathematical details of this concept...

If you wish you can send the working details of the project with pictures and get paid for the submission, I'll publish it in my website.

56. hello, could you please explain what does the transformer the 4 diodes and the condensator do?

1. for stepping down mains voltage and for rectification to pure DC

57. Hi,
for a school project i need to construct an AC induction cooktop and was wondering if you could help me put together a part list for a much weaker induction cooktop than yours, it only has to warm up a few ML's of water. is this something that is possible?

1. Hi, I'll try to explain the design in a new article and post it soon...

58. Hi Swagatam, i love your projects and my son regularly builds them at school in science lessons.
i lastly got him the parts to build a simple Royer style induction heater working from 12v DC but i wonder could your simple inverter circuit using the IR 2153 from 12v DC be changed to build a more exciting and challenging induction circuit ? would it be as simple as adding capacitors to the secondary with working coil?
i thank you in anticipation.

regards Kevin

1. Thanks Kevin, I am glad your son is liking my projects!

my simple inverter circuit is quite similar to the above induction heater concept, so if we try to modify it will ultimately take the shape of the above design.

However the 50 watt mosfet inverter circuit from this website can be definitely tried for making a versatile and a more flexible induction heater circuit:

2. Yes Hi Swagatam, a very interesting self oscillating circuit i will build it one day.
However my aim is to get Dan (my son ) to build something more controllable which is why i mentioned the IR 2153 controller, i would like him to achieve some shutdown / protection techniques either with current a transformer or other direct circuitry and from what i have seen of this IC it does most of this, so if there is any chance of further guidance in this direction i would very much appreciate it.
It does not have to be very powerful but a nice little controllable safe circuit, as in over current and short circuit protection these are the techniques that i would like Dan to start learning.

regards Kevin.

3. sorry Kev, I completely missed the IR2153, the thought you were referring to this circuit:

OK, so referring to the IR2153 design, it can be enhanced with a current control feature by using an ordinary BC547 and a current sensing resistor network across its shutdown Ct pin, this will make sure that the fets can never conduct current above a specified limit

59. Hi, Could you please explain in more detail how the the switching occurs? After the first Mosfet turns on, I don't follow what causes it to turn back off, and the other to turn on. Thank you

1. Hi, since both the fets cannot switch ON together due to the slight difference in their switching characteristics, let's assume T2 initiates first on power switch ON,
as soon as this happens its gate potential is instantly grounded by its own drain/source terminals via D2 and L1....dropping its gate potential to a a level where it's forced to shut off.

This enables T1 to initiate the process and it eventually ends up shutting off in the same manner...the cycle keeps regenerating and continues rapidly giving rise to the required phenomenon...

60. Is the following true?: As the voltage builds on drain one, it causes more voltage to appear at gate 2? And then when Vd1(voltage on drain of T1) hits 15V when the inductive path resistance is a short, Gate 2 now has 15V on it, that drains the voltage on gate 1 to ground? Also, when is the cap being charged and discharged with respect to the rest of the timing of the circuit? Thank you

1. sorry not sure about this analysis, since I am not able to simulate it in my mind

2. That;s OK. What I'm saying, is that after current has been flowing through L2 and the top half of L1 for a while. the voltage on the drain of T1 goes from zero to the supply voltage, which then allows the supply to be applied to the gate of T2, tuning it on. I think.. But since the work coil isn't wound on a core, I see very little, if any, voltage induced in the other half of the work coil. So, I can't figure out how the work cap ever gets charged.

3. No, the voltage at drain will be above zero only when the device is not conducting, and will be zero the moment it starts conducting.

the work coil definitely needs to be mounted on a core otherwise the resonance will never happen and the devices could get damaged.

the core here is the metal which is being heated, that is the iron bolt or rod whatever it may be.

the capacitors, the coil and the iron core together forms a "tank" circuit which reaches the resonance level during the operations and causes the desired heating effect.

4. So a voltage is induced in the bottom half of the work coil when the load is in place?

5. yes, at the drain of the non-conducting fet

61. Hello
what is the maximum temperature which our metallic target reach inside the coil?
and i wanna to know moreover current , what parameters effect on the final temperature (like frequency, voltage , coil diameter , etc) ?
i assembled your designing circle , and the frequency has a tolerance between 70 to 120 kHz,can you give me an advise what's the matter?

i really appreciate it in advance.

1. Hello, it will depend on the input current and the coil wire thickness, and also the voltage level, higher parameters will allow higher temperatures and vice versa.....

it's a self-resonating type of circuit, and the frequency will adjust as per the inductor efficiency.....a better optimized coil will enable better resonance and proportionately more heat.

62. HI, It's possible to melt steel on this kind of power? How could you increase the power by adding more mosfits?

1. It my be possible if the mosfets are appropriately upgraded with higher current ratings and the supply is also proportionately increased with higher current capacity.

63. Hi, thanks for the explanation. Really helpful stuff. I'm trying to make a heating circuit using Li-ion 3.7V battery. The end result is to heat a small piece of stainless steel. Don't know if I can use this technique as the battery power isn't that much. If I can please guide me how and if not , can you provide an alternative ? I'm looking at resistive heating

1. sorry that may not be possible.

you will require at least may be 300 to 500 watts of power for melting a piece of steel which cannot be achieved from a 3.7v cell

2. I don't need to actually melt it. Just to heat it to a temp of around 200deg C. timing isnt crucial. But yes cell power is way too less I think for the application.

3. OK, it may be possible but only for a few seconds

64. hey swagatam im having isues with designing a mini induction heater can i use a set of irfz44n transistors for building a small zvs driver and if possible can you give me a half bridge schematic!

Frank:

1. Hi Frank, you can try the first circuit from this article

2. IRFZ44n will do.

65. Sir
Can i use 12v 80ah battery as input,if not any alternative by using this battery

1. You can use a 12V 80AH battery

66. Thank you so much sir

67. Dear swagatam,
Do you know or can design a electronic circuit to mesure the real magnetic field strength. Generated in the coil. I amen how much mIliTesla i have ?, Thank you in advance

1. Hi Guillermo, I think the circuit can be configured using a Hall effect sensor and an opamp stage, if possible I'll try to publish a design soon.

68. Sir,
. I used 2.5mF / 450v tank capacitor and I used ferrite rod and wound 100 rounds of 1mm copper wire and I connected L1 with insulated coper wire to the second circuit by using transitor and power supply with high guage copper wire to 12v80ah battery and as soon as I supply power , wire (from L1 to circuit )started melting and copper wire arround ferrite rod went to a verry high temperature ,
Can u suggest a solution to my problem

1. Adithya, you must do EXACTLY as suggested in the above article.

use 6 nos of 330nF/400V capacitors in parallel for making the 2uF capacitor, and connect them parallel with the work coil tube ends.

the work coil must be built using copper tubes or very thick copper wires.

don't use the last circuit, it's only a suggestion and needs to be experimented... use the first circuit with schotky diodes.

for more info you can refer to youtube videos...there are plenty of videos which will show you how configure the above type of circuits.

69. Hello good Morning.
I am performing the assembly of an induction heating system,
But the tank coil should have a 16-inch diameter and will be fixed in the heating core, but as the power supply intends to work with the voltage of 220V rectified, it will not cause risk because it will work totally isolated and away from the users.
It would be possible to assist in the calculation of L1 and L2
Noting that the high voltage of the power supply is due to the high power I need.
10KW.
Thank you for the attention
I'm sorry, my English
Any help will be appreciated

1. Hello, the circuit explained in the above article cannot be used with 220V mains or any high voltage above 24V, you have to calculate the parameters specifically for getting the required results from your design.

You can take the help of this article to create a specialized circuit for as per the mentioned specs:

70. how many turns are required for L2 for this circuit?

71. L2 turns will need to be experimented until around 2mH is fixed

72. Sir,
. I have done first circuit by considering all the parameters you have told , it took 5 ferrite rod (each 20cm in length) by winding 1.5 mm copper wire to get 2mH by verifying on LCR meter , and even exat value 6 capacitor connected across parallel as mentioned in the article by giving 2uF , and finaly connected to a battery (12v/ 80ah) no sooner I cgave power supply one of the mosphet reches to a verry high temperature and blow off and other remain cool and this happens within 5-6 seconds

I tried 4times the same circuit , evey time mospfet blow off , ialso used heatsinks

1. Adithya, why did you use 5 ferrite rods? The coil must be wound over a single ferrite rod...if you do anything randomly as per your wish, then you will keep blowing the devices.

which diode did you use for the mosfet gates

did you connect the LC tank as indicated in the 3rd diagram from top??

the L2 must a be neatly wound inductor over a single ferrite rod, the shape does not matter.

secondly your circuit must begin self resonating, and this will strictly depnd on the value of the LC tank circuit and the voltgae.

you must begin with a low volatge may be around 6V and then gradually increase it until you have the best possible results.

while doing this you must have an ammeter connected i series with the input supply, and you just have a iron rod inserted through the work coil. This iron could be any 2cm thick iron bolt, or a 2cm thick screwdriver spindle.

the voltage should be tweaked in a such a way that it results in minimum current consumption and maximum heat on the rod.....a temperature meter could be installed with the iron rod fr monitoring the heat as the voltage is gradually increased....at some point you might find that the current is increasing, and heat going down this is point where you must stop, until this sweet point is not reached you must keep adjusting the voltage with some trial and error.

73. Dear sir,
I need your help . I’m using preethi induction stove. My problem (2uF 275VAC Class X2 Box Type Capacitor) capacitor was Busted but my area only available in (2.2uF 275VAC Class X2 Box Type Capacitor) may I use 2.2uF this capacitor
thank you

1. Dear Satish, according to me it should work, no harm in trying it out....

74. Dear sir.
How many turns should L1 and L2 be? i wish to use this for my cloth dryer project.