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Design of SMPS - Not sure what these spikes are being caused by.
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Zog:
Hi all,
I am making a boost converter for nixie tubes and have got mine running at 185VDC at 140mA's at the moment.
Yes .. I know .. "just how many nixies are you running !" ... well none yet. I just want to see how far I can push the design.

Edit: for this circuit.




My scope is showing these spikes on the HV feedback line.





And these on the Mosfet gate.





After half an hour the vpp was also increasing from almost nothing to this.



Even at only 30mA's I still see the spikes on the feedback line.



The gate does not look so bad though.





Any clues on where I can find out more on this subject would be greatly appreciated.

Cheers,
Phill




Zog:
Could it be my snubber ? Perhaps ?
But what could explain the missing switching in the mosfet ?
Tomorokoshi:
Can you post pictures of the schematic and the actual test setup?
rx8pilot:
The only way to have an actionable comment is to share your schematic, the physical build, and the test setup.

I would hazard a guess that most of what you see is noise from the measurement itself, the rest of it is dominated by how you built (PCB layout) the circuit. Once you have considered those two major elements, you may need a simple RC snubber to damp the ringing on the switch node.

Zog:
I am building this guys design and have used his layout.

https://jan.rychter.com/high-voltage-power-supply-for-nixie-tube-projects

The test setup is not ideal.

Will try the small clips on the probe tomorrow and try again.
Using the crocodile lead is probably making an antenna for sure.
Thanks for the reminders !
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