Spark gaps are very high resistance until the voltage reaches the breakdown rating, then they are a short circuit until the arc clears. Before they fire, there is no way to determine the voltage that each one sees.

So if you want to put two spark gaps in series, you will need to add two series resistors (of very high value) across the spark gaps to make sure they each see half the total voltage.

If you don't do this, the effective breakdown voltage may be just a bit higher than the rating of one of the spark gaps, and it will depend on parasitic effects that are likely not stable, like surrounding humidity.

These resistors will have to be rated for the high voltage across them, and the circuit has to be constructed so that the resistor leads don't form another unintentional spark gap.

This is the same idea as the bleeder resistor stack you will see across the high voltage rectifier stack of a CRT or a tube plate supply. In that case the resistors make sure that each rectifier "shares" the reverse voltage, so that a stack of several rectifiers has a breakdown voltage that is the sum of the individual breakdown ratings. This is the same idea.

So - its not twice the volts with 2 in series??? Do you know this for sure?


And I did my circuit, and it didnt work, the caps had no voltage on them.

But I swear that cross resistor wouldnt matter shit! its a complete short down the diodes, the resistor would get no current, so Ill look at it some more, but something funny seems to be going on.

 

So - its not twice the volts with 2 in series??? Do you know this for sure?


And I did my circuit, and it didnt work, the caps had no voltage on them.

But I swear that cross resistor wouldnt matter shit! its a complete short down the diodes, the resistor would get no current, so Ill look at it some more, but something funny seems to be going on.

No sorry I did a poor measurement, the caps are getting volts, but for some reason my spark gap isnt going off.

I dont seem to be adding up to the larger volt amount.

 

I’m pretty sure that the answer to the original question is 90V; once around 90V is applied, the voltage jumps (breaks-down) across one of the GDT and then the second. Once a GDT conducts, it remains conducting until the current falls below a certain value.

The same is true for multiple GDTs in series, if you placed five 90V GDTs in series, the chain would break-down at around 90V and not 450V for the reason explained above.

Perhaps if someone has a few GDTs to had, they could conduct an experiment to prove me right (or wrong).

 

its not home made, they are professional gas discharge tubes, at 90v, thankyou sir.

A gas discharge tube is not the same as the spark gap you posted about. The gas discharge tube has an inert gas that makes a plasma much faster than normal atmosphere.

 

I’m pretty sure that the answer to the original question is 90V; once around 90V is applied, the voltage jumps (breaks-down) across one of the GDT and then the second. Once a GDT conducts, it remains conducting until the current falls below a certain value.

The same is true for multiple GDT in series, if you placed five 90V GDT in series, the chain would break-down at around 90V and not 450V for the reason explained above.

Perhaps if someone has a few GDTs to had, they could conduct an experiment to prove me right (or wrong).

Yes thankyou! whats I needed to know.