Oversize Snubber Capacitor

[thedark]

What happen if I use a large cap value if a one schematic say one value?

[flyingperson23]

Using a smaller snubber capacitor than is on a schematic might cause problems. A bigger one won't.

[Benbmw]

Depending on the type of snubber (C, RC, RCD) an oversized snubber capacitor could lead to large inrush currents which could damage components with high dI/dt

However it is more likely to not be an issue unless you are over sizing by orders of magnitude

[thedark]

However it is more likely to not be an issue unless you are over sizing by orders of magnitude

The snubber cap in a half bridge say 0.68uF and I only have a 1uf, It wouldn't have much of a problem would it?

Or it posibble make a MMC for a snubber?

[Mads Barnkob]

However it is more likely to not be an issue unless you are over sizing by orders of magnitude

The snubber cap in a half bridge say 0.68uF and I only have a 1uf, It wouldn't have much of a problem would it?

Or it posibble make a MMC for a snubber?

1uF or 0.68uF, as a voltage splitter or DC blocking capacitor, will not make much of a difference.

Being in series with the primary coil, this is not a pure snubber capacitor. More like a DC blocking capacitor and to understand how to size such a thing, check this out: https://kaizerpowerelectronics.dk/tesla-coils/sstc-design-guide/

[thedark]

Oh okay, for the DC blocking capacitor, if I don't have or can't get the one I want, can it also be made of the MMC type, with several in parallel series?

[flyingperson23]

Many DRSSTCs just use the bus capacitors as DC blocking capacitors, i.e. ~1000uF electrolytic caps in place of the 0.68uF ones there for a small DRSSTC. Your schematic seems to be missing a bus capacitor. The more "correct" approach would probably be to use film capacitors, such as WIMA MKP ones, and have the bus capacitors separate. You could make it from MMC capacitors yes, but that would probably be a waste of money.

[davekni]

Many DRSSTCs just use the bus capacitors as DC blocking capacitors, i.e. ~1000uF electrolytic caps in place of the 0.68uF ones there for a small DRSSTC. Your schematic seems to be missing a bus capacitor.

Perhaps this is a ramped coil tracking a line voltage half or quarter cycle?  That is the only cases I've seen without electrolytic bus capacitor(s).  If this is a ramped coil, value of DC blocking film capacitors does make a difference.  Larger capacitors store more energy from previous unused line half-cycles.  This causes a larger initial burst at start of ramp.  Can make startup easier, but also causes usually-unwanted arc branching.

[thedark]

  That is the only cases I've seen without electrolytic bus capacitor(s).  If this is a ramped coil, value of DC blocking film capacitors does make a difference.  Larger capacitors store more energy from previous unused line half-cycles.  This causes a larger initial burst at start of ramp.  Can make startup easier, but also causes usually-unwanted arc branching.

If it's a ramped type, I want to build one similar to the LabCoatz Staccato QCW. I mentioned MMC because I have found a very cheap NOS cap somewhere, maybe I will buy it and try it or better buy capacitors from a reliable source. But I am still seeing and studying what happens with each value of the components when such a value changes, such a thing can happen before I start building it and then lose money on an expensive component.