choice of resistor for marx generator
paulj, Mon Sept 30 2019, 07:30PMHello, I ask a question probably already asked.
I acquired 10 capacitors TDK 2nf 40kv, I want to realize the most powerful possible marx generator
I think I use Wirewound but I don't know how to calculate it's values.
What do you recommend ?
Paul
Re: choice of resistor for marx generator
Plasma, Tue Oct 01 2019, 12:07AM
Hi. This ones are quite reasonable, the site as got quite good stuff
Plasma, Tue Oct 01 2019, 12:07AM
Hi. This ones are quite reasonable, the site as got quite good stuff
Re: choice of resistor for marx generator
Patrick, Tue Oct 01 2019, 07:19AM
Wire wound resistors aren't used for HV, use Ruthenium based resistors meant for it.
Patrick, Tue Oct 01 2019, 07:19AM
Wire wound resistors aren't used for HV, use Ruthenium based resistors meant for it.
Re: choice of resistor for marx generator
paulj, Tue Oct 01 2019, 11:31AM
50 meg is not a bit high? But actually their price is reasonable, for Glass Glaze Film.
Resistance based on ruthenium, can you be more precis?
paulj, Tue Oct 01 2019, 11:31AM
50 meg is not a bit high? But actually their price is reasonable, for Glass Glaze Film.
Resistance based on ruthenium, can you be more precis?
Re: choice of resistor for marx generator
Plasma, Tue Oct 01 2019, 12:15PM
Yeah you could divide by 100 I just looked at the kV
Is it series or parrelel? The below is parrelel.
Plasma, Tue Oct 01 2019, 12:15PM
Yeah you could divide by 100 I just looked at the kV
Is it series or parrelel? The below is parrelel.
Re: choice of resistor for marx generator
paulj, Tue Oct 01 2019, 04:09PM
The stages will be in series.
paulj, Tue Oct 01 2019, 04:09PM
The stages will be in series.
Re: choice of resistor for marx generator
Patrick, Tue Oct 01 2019, 06:32PM
I used to have pics here on the forum, but Caddock, Dale and other makers all use ruthenium (atomic element 44, Ru) for HV, instead of carbon or nichrome. HV can fields above a certain intensity can "squeeze" for lack of a better term the carbon to a different resistance when powered.
dont forget that these resistors which may be rated for 30kV only have 1kV of insulation around the body, so oil or something may be needed.
PICTURES !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!?????????? ???????????????????????
ok look here forgive my website, its abit wrecked at the moment.
Patrick, Tue Oct 01 2019, 06:32PM
paulj wrote ...
Resistance based on ruthenium, can you be more precis?
Resistance based on ruthenium, can you be more precis?
I used to have pics here on the forum, but Caddock, Dale and other makers all use ruthenium (atomic element 44, Ru) for HV, instead of carbon or nichrome. HV can fields above a certain intensity can "squeeze" for lack of a better term the carbon to a different resistance when powered.
dont forget that these resistors which may be rated for 30kV only have 1kV of insulation around the body, so oil or something may be needed.
PICTURES !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!?????????? ???????????????????????
ok look here forgive my website, its abit wrecked at the moment.
Re: choice of resistor for marx generator
MRMILSTAR, Tue Oct 01 2019, 06:50PM
I have one of those Chinese 20-stage Marx generators that I built from a kit. It works well and produces 12" sparks about every 2 seconds. It uses two (one for each side) 10M ohm resistors for the initial stage immediately following the HV supply and 38 (19 on each side) 1M ohm resistors for the subsequent stages. It uses twenty 2 nF capacitors claimed to be rated for 30 KV for the stages. The capacitors and resistors are readily available on E-Bay for low prices. Just google "Marx generator".
I don't claim that any of these values are optimal. It does work well though. Here's a tip though. Use batteries to power your Marx generator. Connecting it to wall power can endanger anything electronic plugged into your house wiring if a HV spike kicks back into your power supply. I destroyed a switching power supply before I switched to battery power.
MRMILSTAR, Tue Oct 01 2019, 06:50PM
I have one of those Chinese 20-stage Marx generators that I built from a kit. It works well and produces 12" sparks about every 2 seconds. It uses two (one for each side) 10M ohm resistors for the initial stage immediately following the HV supply and 38 (19 on each side) 1M ohm resistors for the subsequent stages. It uses twenty 2 nF capacitors claimed to be rated for 30 KV for the stages. The capacitors and resistors are readily available on E-Bay for low prices. Just google "Marx generator".
I don't claim that any of these values are optimal. It does work well though. Here's a tip though. Use batteries to power your Marx generator. Connecting it to wall power can endanger anything electronic plugged into your house wiring if a HV spike kicks back into your power supply. I destroyed a switching power supply before I switched to battery power.
Re: choice of resistor for marx generator
paulj, Tue Oct 01 2019, 06:57PM
Thank you for your answers,
It is nice to listen to different points of view, I was always advised to avoid metal layer resistors for high voltage.
Resistances based on ruthénium are expensive it's boring!
Looking at an old site steve Ward, he used resistors 1 meg carbon (because not expensive) for 560pf capacitors per floor.
I have TDK capacitors uhv-9a I think 1 meg is still too high 500k is a good start?
ps: Like many members of the forum I have difficulties to put my images, it's a shame, I hope to shoot a video at the end of the installation.
paulj, Tue Oct 01 2019, 06:57PM
Thank you for your answers,
It is nice to listen to different points of view, I was always advised to avoid metal layer resistors for high voltage.
Resistances based on ruthénium are expensive it's boring!
Looking at an old site steve Ward, he used resistors 1 meg carbon (because not expensive) for 560pf capacitors per floor.I have TDK capacitors uhv-9a I think 1 meg is still too high 500k is a good start?
ps: Like many members of the forum I have difficulties to put my images, it's a shame, I hope to shoot a video at the end of the installation.
Re: choice of resistor for marx generator
Plasma, Tue Oct 01 2019, 09:48PM
For pictures if you click the tree icon and paste something like htt ps: / /i.ibb.co/SQrbmkm/IMG-20191002-011056.jpg
It should display but its hosted off site.
Plasma, Tue Oct 01 2019, 09:48PM
For pictures if you click the tree icon and paste something like htt ps: / /i.ibb.co/SQrbmkm/IMG-20191002-011056.jpg
It should display but its hosted off site.
Re: choice of resistor for marx generator
paulj, Wed Oct 02 2019, 05:11AM
thank you for the advice on the photos.
there is a seller who offers film resistors for high voltage of this type, the 910k come in my budget; good or bad idea of the old resistances of the Soviet era?
paulj, Wed Oct 02 2019, 05:11AM
thank you for the advice on the photos.
there is a seller who offers film resistors for high voltage of this type, the 910k come in my budget; good or bad idea of the old resistances of the Soviet era?
Re: choice of resistor for marx generator
Sulaiman, Thu Oct 10 2019, 08:43AM
Rather than using resistors you can use inductors for greater efficiency and repetition rate.
Using coupled inductors (e.g. two tall tapped helical coils, each similar to a TC secondary) you can get even greater improvements, at a cost similar to commercial e.h.t. resistors;
e.g.
google:
An example by a 4HV member
This is from my reading, not personally tried.
Sulaiman, Thu Oct 10 2019, 08:43AM
Rather than using resistors you can use inductors for greater efficiency and repetition rate.
Using coupled inductors (e.g. two tall tapped helical coils, each similar to a TC secondary) you can get even greater improvements, at a cost similar to commercial e.h.t. resistors;
e.g.
google:
An example by a 4HV member
This is from my reading, not personally tried.
Re: choice of resistor for marx generator
MRMILSTAR, Thu Oct 10 2019, 02:40PM
I have always wondered why some Marx generators use spherical electrodes. It seems that the best type would be pointed electrodes in order to promote the longest spark and most consistent firing. That is what I use on my 20-stage Marx generator.
MRMILSTAR, Thu Oct 10 2019, 02:40PM
I have always wondered why some Marx generators use spherical electrodes. It seems that the best type would be pointed electrodes in order to promote the longest spark and most consistent firing. That is what I use on my 20-stage Marx generator.
Re: choice of resistor for marx generator
Sulaiman, Fri Oct 11 2019, 11:37AM
'pointy' electrodes wear quickly and do not break down at a constant voltage - even ignoring errosion,
also, from some indirect experience and lots of reading,
it is best if the u.v. emitted by each gap is allowed to 'shine' on the other gaps - to cause all gaps to fire near simultaneously.
Sulaiman, Fri Oct 11 2019, 11:37AM
'pointy' electrodes wear quickly and do not break down at a constant voltage - even ignoring errosion,
also, from some indirect experience and lots of reading,
it is best if the u.v. emitted by each gap is allowed to 'shine' on the other gaps - to cause all gaps to fire near simultaneously.
Re: choice of resistor for marx generator
MRMILSTAR, Fri Oct 11 2019, 03:09PM
I should have been clearer. I was referring to the single "final-stage" electrode pair where the big discharge occurs, not the individual spark gaps for each stage. It seems to me that pointy electrodes would be best for this final stage in order to give the longest and most consistent discharge. This is what I use on my 20-stage Marx generator.
MRMILSTAR, Fri Oct 11 2019, 03:09PM
Sulaiman wrote ...
'pointy' electrodes wear quickly and do not break down at a constant voltage - even ignoring errosion,
also, from some indirect experience and lots of reading,
it is best if the u.v. emitted by each gap is allowed to 'shine' on the other gaps - to cause all gaps to fire near simultaneously.
'pointy' electrodes wear quickly and do not break down at a constant voltage - even ignoring errosion,
also, from some indirect experience and lots of reading,
it is best if the u.v. emitted by each gap is allowed to 'shine' on the other gaps - to cause all gaps to fire near simultaneously.
I should have been clearer. I was referring to the single "final-stage" electrode pair where the big discharge occurs, not the individual spark gaps for each stage. It seems to me that pointy electrodes would be best for this final stage in order to give the longest and most consistent discharge. This is what I use on my 20-stage Marx generator.
Re: choice of resistor for marx generator
Patrick, Sat Oct 12 2019, 02:15AM
can a UV strobe light be used to lower the breakdown threshold uniformly rigt at the best moment ?
Patrick, Sat Oct 12 2019, 02:15AM
Sulaiman wrote ...
... it is best if the u.v. emitted by each gap is allowed to 'shine' on the other gaps - to cause all gaps to fire near simultaneously.
... it is best if the u.v. emitted by each gap is allowed to 'shine' on the other gaps - to cause all gaps to fire near simultaneously.
can a UV strobe light be used to lower the breakdown threshold uniformly rigt at the best moment ?
Re: choice of resistor for marx generator
Plasma, Sat Oct 12 2019, 04:05AM
UV-C range can but it is bad for your eyes, A,B don't have enough energy to ionize.
A lighting supplier will be able to get it.
Plasma, Sat Oct 12 2019, 04:05AM
UV-C range can but it is bad for your eyes, A,B don't have enough energy to ionize.
A lighting supplier will be able to get it.
Re: choice of resistor for marx generator
paulj, Wed Oct 16 2019, 08:16PM
Hello,
Inductors are a good idea, because I can make them to measure.
But I still ordered the resistances cited in the previous post because I had more time to think, I hope not to destroy them, the power supply provides 20 kv to 15 my max.
paulj, Wed Oct 16 2019, 08:16PM
Hello,
Inductors are a good idea, because I can make them to measure.
But I still ordered the resistances cited in the previous post because I had more time to think, I hope not to destroy them, the power supply provides 20 kv to 15 my max.
Re: choice of resistor for marx generator
paulj, Sun Dec 01 2019, 01:53PM
Hello, I think I'm going to need help,
I started my generator for the first time and limited the input power to 6kv, but the problem is that after 15s, the resistance connected to the ground becomes so hot that it can not touch it anymore, I extinguish the machine so as not to destroy it, the others remain cold.
There is no short circuit, the capacitors are all OK, and the new resistors.
-Is the power supply is too powerful (a cxdz cx200c) 6-20kv, 0-15ma.
-are the resistances bad?
reistor films
Power: 2Watt
Rated Voltage: 20KV
910 k film resistors
paulj, Sun Dec 01 2019, 01:53PM
Hello, I think I'm going to need help,
I started my generator for the first time and limited the input power to 6kv, but the problem is that after 15s, the resistance connected to the ground becomes so hot that it can not touch it anymore, I extinguish the machine so as not to destroy it, the others remain cold.
There is no short circuit, the capacitors are all OK, and the new resistors.
-Is the power supply is too powerful (a cxdz cx200c) 6-20kv, 0-15ma.
-are the resistances bad?
reistor films
Power: 2Watt
Rated Voltage: 20KV
910 k film resistors
Re: choice of resistor for marx generator
Patrick, Sun Dec 01 2019, 09:34PM
can you post a schematic ?
Patrick, Sun Dec 01 2019, 09:34PM
can you post a schematic ?
Re: choice of resistor for marx generator
paulj, Tue Dec 03 2019, 12:54PM
Hello,
so I fixed the problem, it was premature sparks on the 1st floor.
I spread spark gap up to 1.4 cm, but the lightning is not more than 25 cm, I'm disappointed!
the power supply is still limited to 6-8 kv, because otherwise the capacitors this discharge too early to the first floor.
Can I push the spaces of the spark gap up to 2 cm without having any incidents and have big lightning ?
capacitor TDK 202k 40kv
thank you
paulj, Tue Dec 03 2019, 12:54PM
Hello,
so I fixed the problem, it was premature sparks on the 1st floor.
I spread spark gap up to 1.4 cm, but the lightning is not more than 25 cm, I'm disappointed!
the power supply is still limited to 6-8 kv, because otherwise the capacitors this discharge too early to the first floor.
Can I push the spaces of the spark gap up to 2 cm without having any incidents and have big lightning ?
capacitor TDK 202k 40kv
thank you
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