Developing HV DC Pulses...

[John Larkin]

On Tue, 16 May 2023 16:04:09 -0700, John Larkin
<jlarkin@highlandSNIPMEtechnology.com> wrote:

On Tue, 9 May 2023 05:27:59 -0700 (PDT), Lamont Cranston
amdx62@gmail.com> wrote:

More oil/water separation.
The AC vs DC separation test was performed and the AC was probably 10 times better. This was a stubborn emulsion, but the AC did work.
( Not throwing DC out yet, need to test other types of oils first.)
Literature says Pulsed DC is best. So to that end, I want to come up with a way to create 500V to 9000V, 1Hz to 1000Hz, HV DC pulses with variable width. Although, I would be satisfied by 1HZ to 100Hz, as literature says a lower frequency is optimum.
The little research I have done shows gated pulses (commercial units) versus a square wave into a step up transformer, and rectifying, I suspect because ringing would be a problem. Looked at old style ignition coil drive circuits, but their wave form is an AC decay signal. Not sure how I could make that a single DC pulse.
I\'m looking at the simple 555 to create the variable pulse, but after that I\'m not sure how to get a decent variable HV DC pulse.
Any ideas to help me are appreciated,
Thanks, Mikek
P.S. We are using a variac driving a neon sign transformer for variable AC voltage and then full wave bridge to get variable DC voltage.
Still waiting on a capacitance and parallel resistance of the test vessel with and without solution.

Here\'s a tube pulser:

https://www.dropbox.com/s/esci7na1lbpa82s/Tube_Pulser_JL_1.zip?dl=0

The push-pull drive version is nice too.

https://www.dropbox.com/s/6d1csywqihhulx9/Tube_Pulser_JL_pp1.zip?dl=0

 

[Lamont Cranston]

On Tuesday, May 16, 2023 at 6:07:22 PM UTC-5, John Larkin wrote:

On Tue, 16 May 2023 11:10:15 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:
On Tuesday, May 16, 2023 at 11:53:08?AM UTC-5, John Larkin wrote:

If you ground one side of such a transformer, it would be bad news.

I have two 9kV transformers both have a secondary CT. connected to the case.

I have not grounded the case, (as of yet).

If I don\'t ground the case can I then ground one side of the secondary?
That would make the case kilovolts live to ground, potentially deadly.

The transformer is mounted in a 14\" x 18\" entirely plastic case with a locked lid.
The real problem I have are four 1-3/4\" x 8\" tall aluminum tubes connected to one side of the HV transformer.
They are front and center in the experiment. I\'d like to put them at ground potential.
So far we are doing AC experiments, so a doubler won\'t do.

Ground the case and use one side. If you need more voltage, use a
doubler or a c-w stack.

Maybe when we go to pulse, I can use the doubler.

I\'m sure you have a good understanding of the connections, but here\'s a drawing of what I want to do.
I think it makes it safer, but I don\'t know if it causes stress within the transformer, i.e. what is the spacing between primary and secondary.
https://www.dropbox.com/s/bclkcb5oqd13bao/Oil%20water%20Transformer%20wiring.jpg?dl=0
The real problem I have are four 1-3/4\" x 8\" tall aluminum tubes connected to one side of the HV transformer. I want them at ground potential, if possible.
Thanks, Mikek

 

[Phil Hobbs]

On 2023-05-16 19:43, John Larkin wrote:

On Tue, 16 May 2023 16:36:19 -0700 (PDT), Lamont Cranston
amdx62@gmail.com> wrote:

On Tuesday, May 16, 2023 at 6:10:19?PM UTC-5, John Larkin wrote:
On Tue, 16 May 2023 11:48:25 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:
On Tuesday, May 16, 2023 at 1:10:20?PM UTC-5, Lamont Cranston wrote:

I sent the 6BK4 asc. file to your work email. I hope that is what you need.
The SUBCKT writer said, if you need anything let me know. So, if you think there is something in the
file that needs correcting he\'s willing to work on it. Apparently, tube subckts are a thing he does
Thanks, Mikek
Got it, tweaked it, posted below.

Does that mean I need 24V to drive the grid?
Does that mean I need a 60V power supply?
I can do that, just want to know if that\'s what the circuit diagram means.
Mikek

It seems to work well with +24 on the grid. The tube turns on hard and
the pulsed grid current is about 25 mA. I assume Dmitry\'s model
handles the positive grid case about right.

Turns out you can use a 50 volt zener from the cathode to ground,
instead of the diode+power supply.

Run the sim and tweak!

It might be a tad different in real life, with a filament connected.

Of course, it\'s pretty unlikely that the tube model was fitted to points
that far out of the normal operating range. But then, there\'s no harm done.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Anthony William Sloman]

On Wednesday, May 17, 2023 at 1:38:08 AM UTC+10, John Larkin wrote:

On Tue, 16 May 2023 07:34:50 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:
On Tuesday, May 16, 2023 at 9:21:50?AM UTC-5, John Larkin wrote:

<snip>

> Are you sure the oil drops expect a DC pulse?

The oil drops don\'t expect anything. They move - fairly slowly - under the influence of an electric field, and what has been written about the approach suggests that sustaining the field for 10 msec works best,

> What does \"DC pulse\" mean anyhow?

A voltage that alternates between two well specified voltages.

DC and AC are short for direct and alternating current, so it\'s not pedantically correct to use them when you are more interested in voltage.

--
Bill Sloman, Sydney

 

[whit3rd]

On Tuesday, May 16, 2023 at 11:10:20 AM UTC-7, Lamont Cranston wrote:

On Tuesday, May 16, 2023 at 11:53:08 AM UTC-5, John Larkin wrote:

If you ground one side of such a transformer, it would be bad news.
I have two 9kV transformers both have a secondary CT. connected to the case.

I have not grounded the case, (as of yet).

If I don\'t ground the case can I then ground one side of the secondary?

No; the insulation between the line windings and the case is probably NOT going to
tolerate kilovolts on the case. And, in case of a wiring fault, the case is a big
chunk of metal that you\'d just as soon wasn\'t hot

 

[Lamont Cranston]

On Wednesday, May 17, 2023 at 3:28:31 AM UTC-5, whit3rd wrote:

On Tuesday, May 16, 2023 at 11:10:20 AM UTC-7, Lamont Cranston wrote:
On Tuesday, May 16, 2023 at 11:53:08 AM UTC-5, John Larkin wrote:

If you ground one side of such a transformer, it would be bad news.
I have two 9kV transformers both have a secondary CT. connected to the case.

I have not grounded the case, (as of yet).

If I don\'t ground the case can I then ground one side of the secondary?
No; the insulation between the line windings and the case is probably NOT going to
tolerate kilovolts on the case. And, in case of a wiring fault, the case is a big
chunk of metal that you\'d just as soon wasn\'t hot

That transformer insulation was my concern, I\'d like to know the construction, I\'ll bet there is a lot of spacing between primary and secondary.
While I understand the hot transformer case danger, the transformer is isolated within a locked plastic case.
I could use a 1 amp fuse and if there was a transformer winding short, it would easily pop the fuse. (I have more transformers)
I\'m just looking for a way around these large a exposed aluminum tubes running at HV.
Any Ideas how to do that?
Last resort, I\'ll build a plexiglas or lexan box around them.
Thanks, Mikek

 

[piglet]

On 15/05/2023 23:56, Lamont Cranston wrote:

Somewhere in this thread John Larkin suggested a neon bulb to indicate HV is present.
I said it probably would be enough of an attention getter.
So, I put a nean tube and an LDR in shrink tube. When the neon tube comes on (about 52Vac)
the LDR drops from 10s of MΩs to 7.5kΩ.
Now my question is,
How do I implement it?
The with the 8 resistor voltage divider, seem we will run at 8KV always. So, I think I can connect
it through a dropping resistor. If I scale the 47KΩ (120V) to 8kV, that says I need a 3.2MΩ resistor.

Is that how it should be done?

Then, when we go to a DC filtered supply, I\'m not sure what to do, because we may repeat
some pulsed experiments at lower kVolts. Then the neon bulb wouldn\'t strike. Can I put back to back
100v zeners across the neon bulb and lower the series resistance to the neon bulb, thinking is, it will strike
at lower voltages, but at higher voltages the zeners keep the voltage drop across the neon at a safe level.
I don\'t know what that safe level is.

Here\'s the circuit I put together, please critic. If it needs changes, fine. I thought the base voltage should be a little lower!
https://www.dropbox.com/s/s8pra9x5bdw7dqx/Neon%20tube%20Relay%20Driver.jpg?dl=0

Thanks, Mikek

You definitely will never need to put zeners across the neon. The neon
will always fire eventually and then hold at a slightly lower voltage.

Size your neon series dropper resistor so not too much current is drawn
at the highest voltage, I think 8kV in your case. The neon will still be
lit at 100V but just a lot dimmer.

piglet

 

[Lamont Cranston]

On Wednesday, May 17, 2023 at 7:46:24 AM UTC-5, piglet wrote:

You definitely will never need to put zeners across the neon. The neon
will always fire eventually and then hold at a slightly lower voltage.

Ok the first spec I saw said current is 0.5ma to 5ma.
I found the GE Glow lamp Manual, https://archive.org/details/GE_Neon_Lamps_1965/mode/2up?view=theater
Page 4 shows well over an amp flowing through a neon tube. Can\'t verify if this causes damage but does shorten lifetime.

Size your neon series dropper resistor so not too much current is drawn
at the highest voltage, I think 8kV in your case. The neon will still be
lit at 100V but just a lot dimmer.

piglet

Wouldn\'t I size the resistor for higher current at 8kV so that it has at least 0.5ma at 100volts?
Thanks, Mikek

 

[John Larkin]

On Wed, 17 May 2023 13:44:18 +0100, piglet <erichpwagner@hotmail.com>
wrote:

On 15/05/2023 23:56, Lamont Cranston wrote:
Somewhere in this thread John Larkin suggested a neon bulb to indicate HV is present.
I said it probably would be enough of an attention getter.
So, I put a nean tube and an LDR in shrink tube. When the neon tube comes on (about 52Vac)
the LDR drops from 10s of M?s to 7.5k?.
Now my question is,
How do I implement it?
The with the 8 resistor voltage divider, seem we will run at 8KV always. So, I think I can connect
it through a dropping resistor. If I scale the 47K? (120V) to 8kV, that says I need a 3.2M? resistor.

Is that how it should be done?

Then, when we go to a DC filtered supply, I\'m not sure what to do, because we may repeat
some pulsed experiments at lower kVolts. Then the neon bulb wouldn\'t strike. Can I put back to back
100v zeners across the neon bulb and lower the series resistance to the neon bulb, thinking is, it will strike
at lower voltages, but at higher voltages the zeners keep the voltage drop across the neon at a safe level.
I don\'t know what that safe level is.

Here\'s the circuit I put together, please critic. If it needs changes, fine. I thought the base voltage should be a little lower!
https://www.dropbox.com/s/s8pra9x5bdw7dqx/Neon%20tube%20Relay%20Driver.jpg?dl=0

Thanks, Mikek





You definitely will never need to put zeners across the neon. The neon
will always fire eventually and then hold at a slightly lower voltage.

Size your neon series dropper resistor so not too much current is drawn
at the highest voltage, I think 8kV in your case. The neon will still be
lit at 100V but just a lot dimmer.

piglet

Put a cap across the neon and it will blink, always the same
brightness.

 

[Lamont Cranston]

On Tuesday, May 16, 2023 at 6:04:25 PM UTC-5, John Larkin wrote:

Here\'s a tube pulser:

https://www.dropbox.com/s/esci7na1lbpa82s/Tube_Pulser_JL_1.zip?dl=0

I have ordered a function generator, this will have a read out for frequency and I can set duty cycle with some specificity.
I think this will simplify setting the input. Does that mod look OK, There is a suggestion to add a zener circuit on the function
generator to prevent any voltage over 6V driven into the function generator.. Will this work, or do I need an interface circuit between
the cathode and the function generator.

https://www.dropbox.com/s/3qn9gu1rmx4zfjf/Pulser%20Function%20generator%20mod.jpg?dl=0

 

[Lamont Cranston]

On Wednesday, May 17, 2023 at 9:19:34 AM UTC-5, John Larkin wrote:

Put a cap across the neon and it will blink, always the same
brightness.

That\'s helpful.
Mikek

 

[John Larkin]

On Wed, 17 May 2023 07:25:09 -0700 (PDT), Lamont Cranston
<amdx62@gmail.com> wrote:

On Tuesday, May 16, 2023 at 6:04:25?PM UTC-5, John Larkin wrote:

Here\'s a tube pulser:

https://www.dropbox.com/s/esci7na1lbpa82s/Tube_Pulser_JL_1.zip?dl=0


I have ordered a function generator, this will have a read out for frequency and I can set duty cycle with some specificity.
I think this will simplify setting the input. Does that mod look OK, There is a suggestion to add a zener circuit on the function
generator to prevent any voltage over 6V driven into the function generator. Will this work, or do I need an interface circuit between
the cathode and the function generator.

https://www.dropbox.com/s/3qn9gu1rmx4zfjf/Pulser%20Function%20generator%20mod.jpg?dl=0

Most any fungen can drive the gate of a mosfet directly. The mosfet is
the interface circuit.

You could add a zener at the fungen output, but it\'s not necessary.
You don\'t need the 50 ohm resistor either.

 

[Lamont Cranston]

On Wednesday, May 17, 2023 at 12:12:08 PM UTC-5, John Larkin wrote:

On Wed, 17 May 2023 07:25:09 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:
On Tuesday, May 16, 2023 at 6:04:25?PM UTC-5, John Larkin wrote:

Here\'s a tube pulser:

https://www.dropbox.com/s/esci7na1lbpa82s/Tube_Pulser_JL_1.zip?dl=0


I have ordered a function generator, this will have a read out for frequency and I can set duty cycle with some specificity.
I think this will simplify setting the input. Does that mod look OK, There is a suggestion to add a zener circuit on the function
generator to prevent any voltage over 6V driven into the function generator. Will this work, or do I need an interface circuit between
the cathode and the function generator.

https://www.dropbox.com/s/3qn9gu1rmx4zfjf/Pulser%20Function%20generator%20mod.jpg?dl=0
Most any fungen can drive the gate of a mosfet directly. The mosfet is
the interface circuit.

You could add a zener at the fungen output, but it\'s not necessary.
You don\'t need the 50 ohm resistor either.

The fungen manual said the edges are fast, so it should be terminated or it will ring.

Probably minor, but, \"Out of an Abundance of Caution\". If I need more output, I can change or remove it.

Mikek

 

[John Larkin]

On Wed, 17 May 2023 10:18:49 -0700 (PDT), Lamont Cranston
<amdx62@gmail.com> wrote:

On Wednesday, May 17, 2023 at 12:12:08?PM UTC-5, John Larkin wrote:
On Wed, 17 May 2023 07:25:09 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:
On Tuesday, May 16, 2023 at 6:04:25?PM UTC-5, John Larkin wrote:

Here\'s a tube pulser:

https://www.dropbox.com/s/esci7na1lbpa82s/Tube_Pulser_JL_1.zip?dl=0


I have ordered a function generator, this will have a read out for frequency and I can set duty cycle with some specificity.
I think this will simplify setting the input. Does that mod look OK, There is a suggestion to add a zener circuit on the function
generator to prevent any voltage over 6V driven into the function generator. Will this work, or do I need an interface circuit between
the cathode and the function generator.

https://www.dropbox.com/s/3qn9gu1rmx4zfjf/Pulser%20Function%20generator%20mod.jpg?dl=0
Most any fungen can drive the gate of a mosfet directly. The mosfet is
the interface circuit.

You could add a zener at the fungen output, but it\'s not necessary.
You don\'t need the 50 ohm resistor either.

The fungen manual said the edges are fast, so it should be terminated or it will ring.

If the gen is a 50 ohm source, that\'s wrong. Loading will cost half
the available voltage swing.

Probably minor, but, \"Out of an Abundance of Caution\". If I need more output, I can change or remove it.

Mikek

 

[Lamont Cranston]

On Wednesday, May 17, 2023 at 12:34:52 PM UTC-5, John Larkin wrote:

The fungen manual said the edges are fast, so it should be terminated or it will ring.

If the gen is a 50 ohm source, that\'s wrong. Loading will cost half
the available voltage swing.

That\'s true, how much voltage swing do I need to drive a 2N7000\"
The manual says, Continuously adjustable from 4 V p-p to 14.5 v p-p, open circuit.
So, a little over 7vpp into 50Ω. A pair of diagonal cutters will solve it, if it\'s a problem.

I\'m gathering parts for the 24V PS. I have 24V regulators, I can make it adjustable from 20V to about 35V.
Good plan? Or would lower up to 24V be better?

Mikek

 

[John Larkin]

On Wed, 17 May 2023 11:00:42 -0700 (PDT), Lamont Cranston
<amdx62@gmail.com> wrote:

On Wednesday, May 17, 2023 at 12:34:52?PM UTC-5, John Larkin wrote:

The fungen manual said the edges are fast, so it should be terminated or it will ring.

If the gen is a 50 ohm source, that\'s wrong. Loading will cost half
the available voltage swing.

That\'s true, how much voltage swing do I need to drive a 2N7000\"
The manual says, Continuously adjustable from 4 V p-p to 14.5 v p-p, open circuit.
So, a little over 7vpp into 50?. A pair of diagonal cutters will solve it, if it\'s a problem.

If 7v p-p means +-3.5, it\'s not enough.

But don\'t believe me about this stuff.

 

[Lamont Cranston]

On Wednesday, May 17, 2023 at 4:46:33 PM UTC-5, John Larkin wrote:

On Wed, 17 May 2023 11:00:42 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:
On Wednesday, May 17, 2023 at 12:34:52?PM UTC-5, John Larkin wrote:

The fungen manual said the edges are fast, so it should be terminated or it will ring.

If the gen is a 50 ohm source, that\'s wrong. Loading will cost half
the available voltage swing.

That\'s true, how much voltage swing do I need to drive a 2N7000\"
The manual says, Continuously adjustable from 4 V p-p to 14.5 v p-p, open circuit.
So, a little over 7vpp into 50?. A pair of diagonal cutters will solve it, if it\'s a problem.

If 7v p-p means +-3.5, it\'s not enough.

But don\'t believe me about this stuff.

It has a DC Pulse called a CMOS output.
Schematic of output section.
https://www.dropbox.com/s/1xe4ayjimh92wyk/B%26K%20output.jpg?dl=0

Mikek

 

[John Larkin]

On Wed, 17 May 2023 15:07:04 -0700 (PDT), Lamont Cranston
<amdx62@gmail.com> wrote:

On Wednesday, May 17, 2023 at 4:46:33?PM UTC-5, John Larkin wrote:
On Wed, 17 May 2023 11:00:42 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:
On Wednesday, May 17, 2023 at 12:34:52?PM UTC-5, John Larkin wrote:

The fungen manual said the edges are fast, so it should be terminated or it will ring.

If the gen is a 50 ohm source, that\'s wrong. Loading will cost half
the available voltage swing.

That\'s true, how much voltage swing do I need to drive a 2N7000\"
The manual says, Continuously adjustable from 4 V p-p to 14.5 v p-p, open circuit.
So, a little over 7vpp into 50?. A pair of diagonal cutters will solve it, if it\'s a problem.

If 7v p-p means +-3.5, it\'s not enough.

But don\'t believe me about this stuff.

It has a DC Pulse called a CMOS output.
Schematic of output section.
https://www.dropbox.com/s/1xe4ayjimh92wyk/B%26K%20output.jpg?dl=0

Mikek

The CMOS output circuit is insane.

 

[Lamont Cranston]

On Wednesday, May 17, 2023 at 8:00:37 PM UTC-5, John Larkin wrote:

On Wed, 17 May 2023 15:07:04 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:
On Wednesday, May 17, 2023 at 4:46:33?PM UTC-5, John Larkin wrote:
On Wed, 17 May 2023 11:00:42 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:
On Wednesday, May 17, 2023 at 12:34:52?PM UTC-5, John Larkin wrote:

The fungen manual said the edges are fast, so it should be terminated or it will ring.

If the gen is a 50 ohm source, that\'s wrong. Loading will cost half
the available voltage swing.

That\'s true, how much voltage swing do I need to drive a 2N7000\"
The manual says, Continuously adjustable from 4 V p-p to 14.5 v p-p, open circuit.
So, a little over 7vpp into 50?. A pair of diagonal cutters will solve it, if it\'s a problem.

If 7v p-p means +-3.5, it\'s not enough.

But don\'t believe me about this stuff.

It has a DC Pulse called a CMOS output.
Schematic of output section.
https://www.dropbox.com/s/1xe4ayjimh92wyk/B%26K%20output.jpg?dl=0

Mikek
The CMOS output circuit is insane.

Not the point John. Will it put out a 7 volt pulse into 50Ω?
Is that enough to saturate the 2N7000.
Here\'s the specifications of the fungen.
https://www.dropbox.com/s/cxfg8aye4pel6sg/B%26K%20specs.jpg?dl=0

I have no idea what your Push pull circuit was, I don\'t have LTspice.
I sent it on to Dmitry, he has modified it, I don\'t know what he did.
Yours to peruse.
https://www.dropbox.com/s/uxwetsrwc9v2lxt/Pulser%20Push%20pull%20as%20Revised%20by%20Dmitry.jpg?dl=0

Thanks, John.

 

[whit3rd]

On Wednesday, May 17, 2023 at 4:03:49 AM UTC-7, Lamont Cranston wrote:

On Wednesday, May 17, 2023 at 3:28:31 AM UTC-5, whit3rd wrote:
On Tuesday, May 16, 2023 at 11:10:20 AM UTC-7, Lamont Cranston wrote:
On Tuesday, May 16, 2023 at 11:53:08 AM UTC-5, John Larkin wrote:

If you ground one side of such a transformer, it would be bad news.
I have two 9kV transformers both have a secondary CT. connected to the case.

I have not grounded the case, (as of yet).

If I don\'t ground the case can I then ground one side of the secondary?
No; the insulation between the line windings and the case is probably NOT going to
tolerate kilovolts on the case. And, in case of a wiring fault, the case is a big
chunk of metal that you\'d just as soon wasn\'t hot
That transformer insulation was my concern, I\'d like to know the construction, I\'ll bet there is a lot of spacing between primary and secondary.

The concern I have, though, is between the primary and the case. That might NOT have
been designed or tested for output-voltage levels.

I\'m just looking for a way around these large a exposed aluminum tubes running at HV.
Any Ideas how to do that?
Last resort, I\'ll build a plexiglas or lexan box around them.

Yeah, that\'s about what I\'d do. Maybe two layers, even, with ceramic
standoffs. But, the transformer was designed and potted so the case could be
safely grounded, I\'d use that too.