High Voltage Forum

High voltage => Voltage Multipliers => Topic started by: Andy Kay on June 06, 2018, 08:13:56 PM

Title: Voltage Multipliers keep destroying drivers
Post by: Andy Kay on June 06, 2018, 08:13:56 PM
I've been playing with Cockcroft Walton and Marx configurations, and I've been running them from a 12V car battery in order to avoid getting high voltage spikes on my mains electrical system. I've used various kinds of devices for stepping up the 12V to provide a feed for the multiplier, such as CCFL inverters, ionizer circuits, and SS Tesla coil drivers, and every time the system works for a short time before the drive stage for the transformer primary coil burns out. Is there a standard way of dealing with this problem?
Title: Re: Voltage Multipliers keep destroying drivers
Post by: FilipŠebík on June 07, 2018, 04:43:07 PM
Limit current or use 1:1 transformer as a protection for HV spikeback (if that's a thing, duh)
Title: Re: Voltage Multipliers keep destroying drivers
Post by: Mads Barnkob on June 08, 2018, 09:14:22 AM
It sounds like you have problems with either inductive kickback/EMF, lack coupling capacitor on the primary side of the transformer to avoid DC offset or you are saturating the transformer from high load and got no protection in the driver against transformer saturation.
Title: Re: Voltage Multipliers keep destroying drivers
Post by: MRMILSTAR on June 15, 2019, 05:19:35 PM
I built one of those Chinese 20-stage Marx generators that you see on E-Bay and was experiencing a similar problem. It would occasionally blow the ZVS driver which was driving the flyback transformer. The problem stumped me for a while. Then one day I noticed that when it fired I could see a dim arc jumping across the resistor isolating the flyback coil from the Marx generator first stage. Some of the discharge energy was feeding back into the flyback coil which then fed back into the ZVS driver. I replaced the 2 resistors with higher voltage units and the problem was solved. You have to check those Chinese designs.
Title: Re: Voltage Multipliers keep destroying drivers
Post by: MRMILSTAR on September 10, 2019, 10:02:25 PM
One potential fix is to place a suitably-rated varistor across the transformer primary.
Title: Re: Voltage Multipliers keep destroying drivers
Post by: johnf on October 10, 2019, 08:40:40 AM
hopefully your transformer has an electrostatic shield between primary and secondary to cancel capacitive coupling primary to secondary especially important if you have flashovers as you will impinge your output voltage as a pulse into your primary circuit
then TVS diodes acroos the drive devices set just below their max voltage and tvs 20 volt diodes gate to source / base to emitter

ignore the above and keep feeding the silicon gods your expensive sacrifices