If the circuit is not oscillating or your coils are saturating they will behave as near short-circuits and overload the supply. Your supply overload lights are on and the supply is reducing its output voltage to protect itself.

 

If the circuit is not oscillating or your coils are saturating they will behave as near short-circuits and overload the supply. Your supply overload lights are on and the supply is reducing its output voltage to protect itself.

Can oscillation be bothered by the pcb traces? I mean in oscillatory circuit everything should be close enough to ensure oscillation takes place. I have etched pcb for the this. Dimensions of pcb is 8.5x7cm

6 caps of 100nf 630 are connected parallel.
Earlier i was thinking of only 2 330nf but then chnged it.

 

You need to kickstart these circuits. That means that you need supply the 12V RIGHT NOW. If you are using that power supply and just turning it on or using the current limit to bring it up slowly, you will destroy a MOSFET if it can't handle the current. If that supply is beefy enough (I doubt it) you could QUICKLY plug the positive lead in to jump start it but if it hits current limit or doesn't have enough to cover the inductive spike.... MOSFET murder.

Either the car battery, recommended earlier, or put a giant cap bank in front of a switch. Charge the cap bank and then engage the switch. This kickstart will get the circuit running. The cheap ones I buy on Amazon call this out.

 

Can oscillation be bothered by the pcb traces? I mean in oscillatory circuit everything should be close enough to ensure oscillation takes place. I have etched pcb for the this. Dimensions of pcb is 8.5x7cmView attachment 174222

6 caps of 100nf 630 are connected parallel.
Earlier i was thinking of only 2 330nf but then chnged it.

Your circuit is a Mazilli driver ,a kind of Royer oscillator.
Key points to check out: 1) are the supply inductors rated for the current and are they large enough.I saw a lot of designs use 100uH.It's job is to keep the high freq oscillation away from the power source.
2)are the MOS transistors the right ones....i used IRF540 in my design and it works ,but dump the zenners for 12V ones since you want a gate voltage as high as possible ,but under max Vgs in the datasheet that states around 20V.Higher Vgs lower Rds on,lower losses. Vds must be high enough to withstand the tank voltage.
3) Switching diodes are a must since it can easily go to hundreds of Khz range.I tried SF 28 G and 1N5822 and both work.For the 1N5822 however don't run it at more than 12V.Since it's a Schottky diode it has a lower breakdown voltage.
4)looses are proportional with the switching freq......so try to measure your working freq.Use an instrument that can withstand 4x your input voltage.At 12V i saw ~60V in the tank circuit. With a tank cap of X value and with the resonance LC tank formula get your L value.Then proceed to adjust the Cap value such that you work around 300khz....just toy with it until the dissipated power is ok.
5)Use a good ,beefy power supply.This circuit does not like slow rising power.I used a computer PSU's 12V line.If you don't have a beefy enough one.....put 2x 1000uF caps at the supply input,let them charge ,then switch on the oscillator.
6)Tank circuit must withstand high currents so use thick cooper wire/pipe for the heater coil and MKP caps for the tank resonance caps.The tank circuit caps and coil must have the lowest inductance possible and be as thick as you can.(the tracks connecting the 2 must be low inductance) my bad exprimation.
7)I recommend using a PC PSU since most have short circuit protection ,but is somewhere at 10A.I'm against using a car battery since if shit goes down you end up shorting a car battery capable of serious currents.If your 6 amp PSU complains means your circuit has problems.It should work at 6A.Not to heat ,but to oscillate at least.

PS:1N4148 does max a few mA.....that thingie will dies fast and probably in flames.
The current that discharges the Gate of the MOS and a part of the current in the V+ resistors gets trough those diodes.
Charge resistors make a big difference.If you lower them you can minimize MOSFET turn on time,but dissipate more power in the diodes and the resistors.Try 470ohms or 390 ohms at 2W or 1W should do too.

 

Your circuit is a Mazilli driver ,a kind of Royer oscillator.
Key points to check out: 1) are the supply inductors rated for the current and are they large enough.I saw a lot of designs use 100uH.It's job is to keep the high freq oscillation away from the power source.
2)are the MOS transistors the right ones....i used IRF540 in my design and it works ,but dump the zenners for 12V ones since you want a gate voltage as high as possible ,but under max Vgs in the datasheet that states around 20V.Higher Vgs lower Rds on,lower losses. Vds must be high enough to withstand the tank voltage.
3) Switching diodes are a must since it can easily go to hundreds of Khz range.I tried SF 28 G and 1N5822 and both work.For the 1N5822 however don't run it at more than 12V.Since it's a Schottky diode it has a lower breakdown voltage.
4)looses are proportional with the switching freq......so try to measure your working freq.Use an instrument that can withstand 4x your input voltage.At 12V i saw ~60V in the tank circuit. With a tank cap of X value and with the resonance LC tank formula get your L value.Then proceed to adjust the Cap value such that you work around 300khz....just toy with it until the dissipated power is ok.
5)Use a good ,beefy power supply.This circuit does not like slow rising power.I used a computer PSU's 12V line.If you don't have a beefy enough one.....put 2x 1000uF caps at the supply input,let them charge ,then switch on the oscillator.
6)Tank circuit must withstand high currents so use thick cooper wire/pipe for the heater coil and MKP caps for the tank resonance caps.The tank circuit caps and coil must have the lowest inductance possible and be as thick as you can.(the tracks connecting the 2 must be low inductance) my bad exprimation.
7)I recommend using a PC PSU since most have short circuit protection ,but is somewhere at 10A.I'm against using a car battery since if shit goes down you end up shorting a car battery capable of serious currents.If your 6 amp PSU complains means your circuit has problems.It should work at 6A.Not to heat ,but to oscillate at least.

PS:1N4148 does max a few mA.....that thingie will dies fast and probably in flames.
The current that discharges the Gate of the MOS and a part of the current in the V+ resistors gets trough those diodes.
Charge resistors make a big difference.If you lower them you can minimize MOSFET turn on time,but dissipate more power in the diodes and the resistors.Try 470ohms or 390 ohms at 2W or 1W should do too.

Your explanation covers everything about the topic.
Many thanks for your help.

 

Your circuit is a Mazilli driver ,a kind of Royer oscillator.
Key points to check out: 1) are the supply inductors rated for the current and are they large enough.I saw a lot of designs use 100uH.It's job is to keep the high freq oscillation away from the power source.
2)are the MOS transistors the right ones....i used IRF540 in my design and it works ,but dump the zenners for 12V ones since you want a gate voltage as high as possible ,but under max Vgs in the datasheet that states around 20V.Higher Vgs lower Rds on,lower losses. Vds must be high enough to withstand the tank voltage.
3) Switching diodes are a must since it can easily go to hundreds of Khz range.I tried SF 28 G and 1N5822 and both work.For the 1N5822 however don't run it at more than 12V.Since it's a Schottky diode it has a lower breakdown voltage.
4)looses are proportional with the switching freq......so try to measure your working freq.Use an instrument that can withstand 4x your input voltage.At 12V i saw ~60V in the tank circuit. With a tank cap of X value and with the resonance LC tank formula get your L value.Then proceed to adjust the Cap value such that you work around 300khz....just toy with it until the dissipated power is ok.
5)Use a good ,beefy power supply.This circuit does not like slow rising power.I used a computer PSU's 12V line.If you don't have a beefy enough one.....put 2x 1000uF caps at the supply input,let them charge ,then switch on the oscillator.
6)Tank circuit must withstand high currents so use thick cooper wire/pipe for the heater coil and MKP caps for the tank resonance caps.The tank circuit caps and coil must have the lowest inductance possible and be as thick as you can.(the tracks connecting the 2 must be low inductance) my bad exprimation.
7)I recommend using a PC PSU since most have short circuit protection ,but is somewhere at 10A.I'm against using a car battery since if shit goes down you end up shorting a car battery capable of serious currents.If your 6 amp PSU complains means your circuit has problems.It should work at 6A.Not to heat ,but to oscillate at least.

PS:1N4148 does max a few mA.....that thingie will dies fast and probably in flames.
The current that discharges the Gate of the MOS and a part of the current in the V+ resistors gets trough those diodes.
Charge resistors make a big difference.If you lower them you can minimize MOSFET turn on time,but dissipate more power in the diodes and the resistors.Try 470ohms or 390 ohms at 2W or 1W should do too.

Here is the thing.

Did changes according to you and got the circuit working.

As told by you to measure the working frequency of output and which is 22.7khz
I'm using capacitor bank made by 6 100nF 630V polyester caps, which gives the inductors value to be 81.9uH. as mentioned by you to use frequency of around 300khz. I took 270khz and did calculation and the value for caps turns out to be around 3 to 4nF. Isn't value too low?

I dont understand which inductors' value i got. Is this the average of 2 inductances?