Developing HV DC Pulses...

[Anthony William Sloman]

On Saturday, May 13, 2023 at 4:38:21 AM UTC+10, Lamont Cranston wrote:

On Friday, May 12, 2023 at 9:42:37 AM UTC-5, Anthony William Sloman wrote:

Mikek\'s experiments with his neon sign transformer produce strange results - the fact that he has to load the output with 2.5M of resistance before he can see a half wave suggests that there are capacitors embedded in his set-up. The fact that 18pF killed it off again says that it might just be the interwinding capacitance in the transformer - easy enough to measure if you know what you are doing.

I don\'t doubt there is a large self capacitance in the secondary, there are lots of turns.

But their arrangement can make a lot of difference. A secondary tat is wound as a series of layers, one on top of another, has a higher interwinding capacitance than one that is banked, wound as series of multilayer coils, each one stacked on top of one another electrically speaking, while physically side by side.

> Well, I thought I knew what I was doing, I used C1-4C2 / 3.

But what do you think you are doing?

But C1 = 3,208pf @ 75Hz and C2 = 945pf @ 150Hz.
3208 - (4x 945) / 3 = 3208 -3780 / 3
That doesn\'t compute, I did it twice and got very similar results.
Any help?

Every last bit of capacitance inside the transformer has got to get charged up when you apply a voltage across the transfomer. You\'ve thrown a few diodes into the system and it looks as if you are charging some of those capacitances with DC and revers biasing the diodes inot thier non-conducting state for most of the time.

You need to think harder about what you are looking at.

--
Bill Sloman, Sydney

 

[Anthony William Sloman]

On Saturday, May 13, 2023 at 1:13:12 PM UTC+10, John Larkin wrote:

On Fri, 12 May 2023 13:43:56 -0700 (PDT), Lamont Cranston <amd...@gmail.com> wrote:
On Friday, May 12, 2023 at 3:38:19?PM UTC-5, John Larkin wrote:
On Fri, 12 May 2023 13:25:24 -0700 (PDT), Lamont Cranston <amd...@gmail.com> wrote:
On Friday, May 12, 2023 at 2:51:36?PM UTC-5, John Larkin wrote:
On Fri, 12 May 2023 11:41:52 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:
On Friday, May 12, 2023 at 1:15:40?PM UTC-5, John Larkin wrote:

Where\'s Sloman\'s design? I really wanted to see that.

Here\'s a suggestion.

https://www.dropbox.com/s/lm7aqo3e3892hhb/6BK4_Pulser_1.jpg?raw=1

It needs to be tested and maybe tweaked. I haven\'t designed with tubes lately.

As suggestions go it is pretty vague. And the 555 timer is out of the ark. Use a single chip processor with a built in A/D and you can at least adjust the timing to fit with what the circuit is doing at any given time. And the time intervals are likely to be a whole lot more precise than you can get out of a 555 (not that this s likely to matter).

--
Bill Sloman, Sydney

 

[Lamont Cranston]

On Saturday, May 13, 2023 at 12:11:47 AM UTC-5, Anthony William Sloman wrote:

On Saturday, May 13, 2023 at 4:38:21 AM UTC+10, Lamont Cranston wrote:
On Friday, May 12, 2023 at 9:42:37 AM UTC-5, Anthony William Sloman wrote:

Mikek\'s experiments with his neon sign transformer produce strange results - the fact that he has to load the output with 2.5M of resistance before he can see a half wave suggests that there are capacitors embedded in his set-up. The fact that 18pF killed it off again says that it might just be the interwinding capacitance in the transformer - easy enough to measure if you know what you are doing.

I don\'t doubt there is a large self capacitance in the secondary, there are lots of turns.
But their arrangement can make a lot of difference. A secondary tat is wound as a series of layers, one on top of another, has a higher interwinding capacitance than one that is banked, wound as series of multilayer coils, each one stacked on top of one another electrically speaking, while physically side by side.
Well, I thought I knew what I was doing, I used C1-4C2 / 3.
But what do you think you are doing?
But C1 = 3,208pf @ 75Hz and C2 = 945pf @ 150Hz.
3208 - (4x 945) / 3 = 3208 -3780 / 3
That doesn\'t compute, I did it twice and got very similar results.
Any help?
Every last bit of capacitance inside the transformer has got to get charged up when you apply a voltage across the transfomer. You\'ve thrown a few diodes into the system and it looks as if you are charging some of those capacitances with DC and revers biasing the diodes inot thier non-conducting state for most of the time.

You need to think harder about what you are looking at.

--
Bill Sloman, Sydney

But what do you think you are doing?

Trying to solve for self capacitance.

 

[Lamont Cranston]

On Friday, May 12, 2023 at 10:13:12 PM UTC-5, John Larkin wrote:

Where\'s Sloman\'s design? I really wanted to see that.

Here\'s a suggestion.

https://www.dropbox.com/s/lm7aqo3e3892hhb/6BK4_Pulser_1.jpg?raw=1

It needs to be tested and maybe tweaked. I haven\'t designed with tubes
lately.

Ahh, great John, I have been looking at grounded grid schematics, but not with your twist.
Now, I\'m waiting for parts.

I need to start thinking about a filter cap for my DC. I have seven, 1uf 2000V caps from microwave ovens.
That\'s 140nF.

Any reason I can\'t series them, as a first iteration filter?

Upgrade when if we go to higher voltages. Pretty sure they have built in 1MΩ parallel resistors.

Thanks, Mikek

 

[Lamont Cranston]

On Saturday, May 13, 2023 at 12:19:34 AM UTC-5, Anthony William Sloman wrote:

As suggestions go it is pretty vague. And the 555 timer is out of the ark.. Use a single chip processor with a built in A/D and you can at least adjust the timing to fit with what the circuit is doing at any given time. And the time intervals are likely to be a whole lot more precise than you can get out of a 555 (not that this s likely to matter).

--
Bill Sloman, Sydney

Bill, great idea, but for later, it could be very useful as so far, it seems different oils need different treatments. Developing that would be time killer for me, I could probably get it done with enough time but for these preliminary tests, I think a 555 will be fine, but it\'s in the note book.
Thanks, Mikek

 

[John Larkin]

On Fri, 12 May 2023 23:42:50 -0700 (PDT), Lamont Cranston
<amdx62@gmail.com> wrote:

On Friday, May 12, 2023 at 10:13:12?PM UTC-5, John Larkin wrote:

Where\'s Sloman\'s design? I really wanted to see that.

Here\'s a suggestion.

https://www.dropbox.com/s/lm7aqo3e3892hhb/6BK4_Pulser_1.jpg?raw=1

It needs to be tested and maybe tweaked. I haven\'t designed with tubes
lately.

Ahh, great John, I have been looking at grounded grid schematics, but not with your twist.
Now, I\'m waiting for parts.

I thought it was cute to have a single 6-volt power supply, but that
nails the positive grid (I keep wanting to say gate) drive at 6 too.

Whit\'s idea of push-pull drive is cute but needs another power supply,
and in its most basic form forces the + and - grid voltages to be
equal, although that is probably OK and easily fixed. One 556, the
dual 555, could drive both the grid and the cathode.

You should build in the scope pickoff, so you can see what\'s going on.
We usually build in a signal pickoff/monitor circuit on pulsers.

I need to start thinking about a filter cap for my DC. I have seven, 1uf 2000V caps from microwave ovens.
That\'s 140nF.

Any reason I can\'t series them, as a first iteration filter?

Upgrade when if we go to higher voltages. Pretty sure they have built in 1M? parallel resistors.

Thanks, Mikek

You don\'t need much filter capacitance, driving a 10 Meg load, and
ripple won\'t matter much here. Equalizing/discharge resistors are a
good idea. Safety warning: a neon bulb relaxation oscillator. [1] [2]

I used to get military surplus HV oil caps, big metal cans.

Last-gen CRT-type TVs used to have a potted flyback-rectifier thing,
which would be another way to get HV. I\'d expect that ebay has some.
They could make 25KV or some such, conveniently positive, and are
small and light and relatively safe. I think they used the CRT bulb as
the filter cap, but the flyback freq was 15K so they didn\'t need much
cap. There are old TV doorknob caps too.

[1] I had a project where I wanted to blink an LED from a HV supply,
which is an interesting problem. The breadboard worked but the
customer went away.

[2] Two neons in parallel is fun too. That was in an old PopTronics
mag.

 

[Lamont Cranston]

On Saturday, May 13, 2023 at 8:50:52 AM UTC-5, John Larkin wrote:

On Fri, 12 May 2023 23:42:50 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:
On Friday, May 12, 2023 at 10:13:12?PM UTC-5, John Larkin wrote:

Where\'s Sloman\'s design? I really wanted to see that.

Here\'s a suggestion.

https://www.dropbox.com/s/lm7aqo3e3892hhb/6BK4_Pulser_1.jpg?raw=1

It needs to be tested and maybe tweaked. I haven\'t designed with tubes
lately.

Ahh, great John, I have been looking at grounded grid schematics, but not with your twist.
Now, I\'m waiting for parts.
I thought it was cute to have a single 6-volt power supply, but that
nails the positive grid (I keep wanting to say gate) drive at 6 too.

Whit\'s idea of push-pull drive is cute but needs another power supply,
and in its most basic form forces the + and - grid voltages to be
equal, although that is probably OK and easily fixed. One 556, the
dual 555, could drive both the grid and the cathode.

I\'m already thinking about two neon sign transformers, and another
complete tube switcher, with opposite polarity, so it will ± 7kV for a 14KV differential.

Would we build a negative switcher or to positives and invert the input to one?

You should build in the scope pickoff, so you can see what\'s going on.
We usually build in a signal pickoff/monitor circuit on pulsers.

Agree on that, Need to source a 1nF HV cap.

I need to start thinking about a filter cap for my DC. I have seven, 1uf 2000V caps from microwave ovens.
That\'s 140nF.

Any reason I can\'t series them, as a first iteration filter?

Upgrade when if we go to higher voltages. Pretty sure they have built in 1M? parallel resistors.

Thanks, Mikek

You don\'t need much filter capacitance, driving a 10 Meg load, and
ripple won\'t matter much here. Equalizing/discharge resistors are a
good idea. Safety warning: a neon bulb relaxation oscillator. [1] [2]

I have searched for a Red blinking light, that would power on when the power is turned on.
I have couple setting in my Amazon cart, but as yet unsure what to do.
Now that filter caps are involved, I need something that will display until the filter caps are discharged.
I\'m not sure a neon bulb would be enough of an attention getter.
Maybe a neon bulb and a phototransistor to trigger the red flasher until the HVDC is diminished
But yes safety is of great importance.

I used to get military surplus HV oil caps, big metal cans.

Last-gen CRT-type TVs used to have a potted flyback-rectifier thing,
which would be another way to get HV. I\'d expect that ebay has some.
They could make 25KV or some such, conveniently positive, and are
small and light and relatively safe. I think they used the CRT bulb as
the filter cap, but the flyback freq was 15K so they didn\'t need much
cap. There are old TV doorknob caps too.

[1] I had a project where I wanted to blink an LED from a HV supply,
which is an interesting problem. The breadboard worked but the
customer went away.

[2] Two neons in parallel is fun too. That was in an old PopTronics
mag.

 

[Lamont Cranston]

That should have said I need to source a HV 1pf capacitor.
Mikek

 

[John Larkin]

On Sat, 13 May 2023 08:07:17 -0700 (PDT), Lamont Cranston
<amdx62@gmail.com> wrote:

On Saturday, May 13, 2023 at 8:50:52?AM UTC-5, John Larkin wrote:
On Fri, 12 May 2023 23:42:50 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:
On Friday, May 12, 2023 at 10:13:12?PM UTC-5, John Larkin wrote:

Where\'s Sloman\'s design? I really wanted to see that.

Here\'s a suggestion.

https://www.dropbox.com/s/lm7aqo3e3892hhb/6BK4_Pulser_1.jpg?raw=1

It needs to be tested and maybe tweaked. I haven\'t designed with tubes
lately.

Ahh, great John, I have been looking at grounded grid schematics, but not with your twist.
Now, I\'m waiting for parts.
I thought it was cute to have a single 6-volt power supply, but that
nails the positive grid (I keep wanting to say gate) drive at 6 too.

Whit\'s idea of push-pull drive is cute but needs another power supply,
and in its most basic form forces the + and - grid voltages to be
equal, although that is probably OK and easily fixed. One 556, the
dual 555, could drive both the grid and the cathode.

I\'m already thinking about two neon sign transformers, and another
complete tube switcher, with opposite polarity, so it will ± 7kV for a 14KV differential.

The oil emulsion thing is inherently AC-coupled, no? One supply and
one tube does that.

And one neon sign transformer could make +-HV if you really wanted
that.

Would we build a negative switcher or to positives and invert the input to one?

I think Whit\'s idea is to drive the grid and cathode of the one tube,
0 and +12 maybe, antiphase. Not to have pos and neg HV.

My suggested circuit works well making low duty cycle negative HV
pulses. Positive-going pulses would be harder.

You should build in the scope pickoff, so you can see what\'s going on.
We usually build in a signal pickoff/monitor circuit on pulsers.

Agree on that, Need to source a 1nF HV cap.

Make it!

I need to start thinking about a filter cap for my DC. I have seven, 1uf 2000V caps from microwave ovens.
That\'s 140nF.

Any reason I can\'t series them, as a first iteration filter?

Upgrade when if we go to higher voltages. Pretty sure they have built in 1M? parallel resistors.

Thanks, Mikek

You don\'t need much filter capacitance, driving a 10 Meg load, and
ripple won\'t matter much here. Equalizing/discharge resistors are a
good idea. Safety warning: a neon bulb relaxation oscillator. [1] [2]

I have searched for a Red blinking light, that would power on when the power is turned on.
I have couple setting in my Amazon cart, but as yet unsure what to do.
Now that filter caps are involved, I need something that will display until the filter caps are discharged.
I\'m not sure a neon bulb would be enough of an attention getter.
Maybe a neon bulb and a phototransistor to trigger the red flasher until the HVDC is diminished
But yes safety is of great importance.


I used to get military surplus HV oil caps, big metal cans.

Last-gen CRT-type TVs used to have a potted flyback-rectifier thing,
which would be another way to get HV. I\'d expect that ebay has some.
They could make 25KV or some such, conveniently positive, and are
small and light and relatively safe. I think they used the CRT bulb as
the filter cap, but the flyback freq was 15K so they didn\'t need much
cap. There are old TV doorknob caps too.

[1] I had a project where I wanted to blink an LED from a HV supply,
which is an interesting problem. The breadboard worked but the
customer went away.

[2] Two neons in parallel is fun too. That was in an old PopTronics
mag.

 

[Anthony William Sloman]

On Sunday, May 14, 2023 at 1:13:35 AM UTC+10, Lamont Cranston wrote:

That should have said I need to source a HV 1pf capacitor.
Mikek

High voltage coax cable tend to work out around 1pF per cm (or 2.5pf per inch) like every other kind of coax cable.

--
Bill Sloman, Sydney

 

[Anthony William Sloman]

On Sunday, May 14, 2023 at 1:55:03 AM UTC+10, John Larkin wrote:

On Sat, 13 May 2023 08:07:17 -0700 (PDT), Lamont Cranston <amd...@gmail.com> wrote:
On Saturday, May 13, 2023 at 8:50:52?AM UTC-5, John Larkin wrote:
On Fri, 12 May 2023 23:42:50 -0700 (PDT), Lamont Cranston <amd...@gmail.com> wrote:
On Friday, May 12, 2023 at 10:13:12?PM UTC-5, John Larkin wrote:

<snip>

> The oil emulsion thing is inherently AC-coupled, no? One supply and one tube does that.

It\'s electrophoresis. It\'s actually DC coupled. The droplets of oil suspended in water (or droplets of water suspended in oil) have a small electric charge with respect tot eh surrounding fluid in which they are suspoended - which is how the field moves them, and the suspension gets broken when the droplets get pulled onto the electrodes and the charge flows on into the voltage source generating the bias.

<snip>

--
Bill Sloman. Sydney

 

[Lamont Cranston]

On Saturday, May 13, 2023 at 10:55:03 AM UTC-5, John Larkin wrote:

On Sat, 13 May 2023 08:07:17 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:
On Saturday, May 13, 2023 at 8:50:52?AM UTC-5, John Larkin wrote:
On Fri, 12 May 2023 23:42:50 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:
On Friday, May 12, 2023 at 10:13:12?PM UTC-5, John Larkin wrote:

Where\'s Sloman\'s design? I really wanted to see that.

Here\'s a suggestion.

https://www.dropbox.com/s/lm7aqo3e3892hhb/6BK4_Pulser_1.jpg?raw=1

It needs to be tested and maybe tweaked. I haven\'t designed with tubes
lately.

Ahh, great John, I have been looking at grounded grid schematics, but not with your twist.
Now, I\'m waiting for parts.
I thought it was cute to have a single 6-volt power supply, but that
nails the positive grid (I keep wanting to say gate) drive at 6 too.

Whit\'s idea of push-pull drive is cute but needs another power supply,
and in its most basic form forces the + and - grid voltages to be
equal, although that is probably OK and easily fixed. One 556, the
dual 555, could drive both the grid and the cathode.

I\'m already thinking about two neon sign transformers, and another
complete tube switcher, with opposite polarity, so it will ą 7kV for a 14KV differential.

I was thinking the differential to get higher voltage, in the end I would like to have 30kV,
whether that is single sided or ± I don\'t know what is best.

The oil emulsion thing is inherently AC-coupled, no? One supply and
one tube does that.

And one neon sign transformer could make +-HV if you really wanted
that.

Would we build a negative switcher or to positives and invert the input to one?
I think Whit\'s idea is to drive the grid and cathode of the one tube,
0 and +12 maybe, antiphase. Not to have pos and neg HV.

I don\'t understand that.

My suggested circuit works well making low duty cycle negative HV
pulses. Positive-going pulses would be harder.

OK, I think that is a logic thing. Since the circuit is acting to bring the output to 0V,
you are calling that negative HV pulses?

You should build in the scope pickoff, so you can see what\'s going on.
We usually build in a signal pickoff/monitor circuit on pulsers.

Agree on that, Need to source a 1nF HV cap.
Make it!

Ya, I already looked at dielectric breakdown voltages, it seems it takes a thick dielectric.

A 1\" long copper pipe with a 0.25\" copper pipe in the center is 2pf.
If I fill it with silicone sealer (~3) I\'m up to 6pf and can shorten it considerably.

Is silicone sealer better than air for breakdown voltage?

 

[John Larkin]

On Sat, 13 May 2023 09:37:47 -0700 (PDT), Lamont Cranston
<amdx62@gmail.com> wrote:

On Saturday, May 13, 2023 at 10:55:03?AM UTC-5, John Larkin wrote:
On Sat, 13 May 2023 08:07:17 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:
On Saturday, May 13, 2023 at 8:50:52?AM UTC-5, John Larkin wrote:
On Fri, 12 May 2023 23:42:50 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:
On Friday, May 12, 2023 at 10:13:12?PM UTC-5, John Larkin wrote:

Where\'s Sloman\'s design? I really wanted to see that.

Here\'s a suggestion.

https://www.dropbox.com/s/lm7aqo3e3892hhb/6BK4_Pulser_1.jpg?raw=1

It needs to be tested and maybe tweaked. I haven\'t designed with tubes
lately.

Ahh, great John, I have been looking at grounded grid schematics, but not with your twist.
Now, I\'m waiting for parts.
I thought it was cute to have a single 6-volt power supply, but that
nails the positive grid (I keep wanting to say gate) drive at 6 too.

Whit\'s idea of push-pull drive is cute but needs another power supply,
and in its most basic form forces the + and - grid voltages to be
equal, although that is probably OK and easily fixed. One 556, the
dual 555, could drive both the grid and the cathode.

I\'m already thinking about two neon sign transformers, and another
complete tube switcher, with opposite polarity, so it will ? 7kV for a 14KV differential.

I was thinking the differential to get higher voltage, in the end I would like to have 30kV,
whether that is single sided or ± I don\'t know what is best.

The oil emulsion thing is inherently AC-coupled, no? One supply and
one tube does that.

And one neon sign transformer could make +-HV if you really wanted
that.


Would we build a negative switcher or to positives and invert the input to one?
I think Whit\'s idea is to drive the grid and cathode of the one tube,
0 and +12 maybe, antiphase. Not to have pos and neg HV.

I don\'t understand that.

Make a 0 to 12 volt positive pulse and apply it to the grid. Invert
it, still 0 to +12 but out of phase, and connect that to the cathode.
So the grid is usually -12 relative to the cathode and +12 during the
pulse. You can do it all with one NE556.

I hate the concept because I didn\'t invent it.

My suggested circuit works well making low duty cycle negative HV
pulses. Positive-going pulses would be harder.

OK, I think that is a logic thing. Since the circuit is acting to bring the output to 0V,
you are calling that negative HV pulses?

If a voltage is high positive and occasionally blips to ground, I call
that a negative pulse. Or negative-going maybe. Like the OUT here:

https://www.dropbox.com/s/lm7aqo3e3892hhb/6BK4_Pulser_1.jpg?dl=0

The tube circuit does that well. The opposite is trickier, frys the
resistors among other things.

You should build in the scope pickoff, so you can see what\'s going on.
We usually build in a signal pickoff/monitor circuit on pulsers.

Agree on that, Need to source a 1nF HV cap.
Make it!

Ya, I already looked at dielectric breakdown voltages, it seems it takes a thick dielectric.

A 1\" long copper pipe with a 0.25\" copper pipe in the center is 2pf.
If I fill it with silicone sealer (~3) I\'m up to 6pf and can shorten it considerably.

That\'s complex. I was thinking of a variant on the gimmick capacitor,
namely two pieces of insulated wire, parallel, with shrink tubing
overall. Or two layers on a PC board.

You could hack a small piece of copperclad FR4 too, and add wires. The
usual stuff is about 15 pF per square inch. You could make the entire
attenuator out of one piece of dremeled FR4!

 

[Lamont Cranston]

On Saturday, May 13, 2023 at 1:46:08 PM UTC-5, John Larkin wrote:

On Sat, 13 May 2023 09:37:47 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:
On Saturday, May 13, 2023 at 10:55:03?AM UTC-5, John Larkin wrote:
On Sat, 13 May 2023 08:07:17 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:
On Saturday, May 13, 2023 at 8:50:52?AM UTC-5, John Larkin wrote:
On Fri, 12 May 2023 23:42:50 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:
On Friday, May 12, 2023 at 10:13:12?PM UTC-5, John Larkin wrote:

Where\'s Sloman\'s design? I really wanted to see that.

Here\'s a suggestion.

https://www.dropbox.com/s/lm7aqo3e3892hhb/6BK4_Pulser_1.jpg?raw=1

It needs to be tested and maybe tweaked. I haven\'t designed with tubes
lately.

Ahh, great John, I have been looking at grounded grid schematics, but not with your twist.
Now, I\'m waiting for parts.
I thought it was cute to have a single 6-volt power supply, but that
nails the positive grid (I keep wanting to say gate) drive at 6 too..

Whit\'s idea of push-pull drive is cute but needs another power supply,
and in its most basic form forces the + and - grid voltages to be
equal, although that is probably OK and easily fixed. One 556, the
dual 555, could drive both the grid and the cathode.

I\'m already thinking about two neon sign transformers, and another
complete tube switcher, with opposite polarity, so it will ? 7kV for a 14KV differential.

I was thinking the differential to get higher voltage, in the end I would like to have 30kV,
whether that is single sided or ą I don\'t know what is best.

The oil emulsion thing is inherently AC-coupled, no? One supply and
one tube does that.

And one neon sign transformer could make +-HV if you really wanted
that.


Would we build a negative switcher or to positives and invert the input to one?
I think Whit\'s idea is to drive the grid and cathode of the one tube,
0 and +12 maybe, antiphase. Not to have pos and neg HV.

I don\'t understand that.
Make a 0 to 12 volt positive pulse and apply it to the grid. Invert
it, still 0 to +12 but out of phase, and connect that to the cathode.
So the grid is usually -12 relative to the cathode and +12 during the
pulse. You can do it all with one NE556.

I hate the concept because I didn\'t invent it.

My suggested circuit works well making low duty cycle negative HV
pulses. Positive-going pulses would be harder.

OK, I think that is a logic thing. Since the circuit is acting to bring the output to 0V,
you are calling that negative HV pulses?
If a voltage is high positive and occasionally blips to ground, I call
that a negative pulse. Or negative-going maybe. Like the OUT here:

https://www.dropbox.com/s/lm7aqo3e3892hhb/6BK4_Pulser_1.jpg?dl=0

The tube circuit does that well. The opposite is trickier, frys the
resistors among other things.



You should build in the scope pickoff, so you can see what\'s going on.
We usually build in a signal pickoff/monitor circuit on pulsers.

Agree on that, Need to source a 1nF HV cap.
Make it!

Ya, I already looked at dielectric breakdown voltages, it seems it takes a thick dielectric.

A 1\" long copper pipe with a 0.25\" copper pipe in the center is 2pf.
If I fill it with silicone sealer (~3) I\'m up to 6pf and can shorten it considerably.
That\'s complex. I was thinking of a variant on the gimmick capacitor,
namely two pieces of insulated wire, parallel, with shrink tubing
overall. Or two layers on a PC board.

You could hack a small piece of copperclad FR4 too, and add wires. The
usual stuff is about 15 pF per square inch. You could make the entire
attenuator out of one piece of dremeled FR4!

Maybe I\'m being to concerned with arc over. I have made disc caps using Rogers 5880 (0.036\"),
using a paper punch, they are about 1.3pf. But, I think the 5880 is too thin.

If I use FR4, what is the max voltage you would go? Assumes the FR4 is larger than the copper.

Mikek

 

[ehsjr]

On 5/13/2023 12:37 PM, Lamont Cranston wrote:

On Saturday, May 13, 2023 at 10:55:03 AM UTC-5, John Larkin wrote:
On Sat, 13 May 2023 08:07:17 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:
On Saturday, May 13, 2023 at 8:50:52?AM UTC-5, John Larkin wrote:
On Fri, 12 May 2023 23:42:50 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:
On Friday, May 12, 2023 at 10:13:12?PM UTC-5, John Larkin wrote:

Where\'s Sloman\'s design? I really wanted to see that.

Here\'s a suggestion.

https://www.dropbox.com/s/lm7aqo3e3892hhb/6BK4_Pulser_1.jpg?raw=1

It needs to be tested and maybe tweaked. I haven\'t designed with tubes
lately.

Ahh, great John, I have been looking at grounded grid schematics, but not with your twist.
Now, I\'m waiting for parts.
I thought it was cute to have a single 6-volt power supply, but that
nails the positive grid (I keep wanting to say gate) drive at 6 too.

Whit\'s idea of push-pull drive is cute but needs another power supply,
and in its most basic form forces the + and - grid voltages to be
equal, although that is probably OK and easily fixed. One 556, the
dual 555, could drive both the grid and the cathode.

I\'m already thinking about two neon sign transformers, and another
complete tube switcher, with opposite polarity, so it will ą 7kV for a 14KV differential.

I was thinking the differential to get higher voltage, in the end I would like to have 30kV,
whether that is single sided or ± I don\'t know what is best.

The oil emulsion thing is inherently AC-coupled, no? One supply and
one tube does that.

And one neon sign transformer could make +-HV if you really wanted
that.


Would we build a negative switcher or to positives and invert the input to one?
I think Whit\'s idea is to drive the grid and cathode of the one tube,
0 and +12 maybe, antiphase. Not to have pos and neg HV.

I don\'t understand that.

My suggested circuit works well making low duty cycle negative HV
pulses. Positive-going pulses would be harder.

OK, I think that is a logic thing. Since the circuit is acting to bring the output to 0V,
you are calling that negative HV pulses?



You should build in the scope pickoff, so you can see what\'s going on.
We usually build in a signal pickoff/monitor circuit on pulsers.

Agree on that, Need to source a 1nF HV cap.
Make it!

Ya, I already looked at dielectric breakdown voltages, it seems it takes a thick dielectric.

A 1\" long copper pipe with a 0.25\" copper pipe in the center is 2pf.
If I fill it with silicone sealer (~3) I\'m up to 6pf and can shorten it considerably.

Is silicone sealer better than air for breakdown voltage?

Teflon tape is what I\'d use. (6000 V/mil according to American
Durafilm) Wrap the center conductor with multiple layers so
that it fits snugly in the outer pipe.
Ed

 

[John Larkin]

On Sat, 13 May 2023 12:49:33 -0700 (PDT), Lamont Cranston
<amdx62@gmail.com> wrote:

On Saturday, May 13, 2023 at 1:46:08?PM UTC-5, John Larkin wrote:
On Sat, 13 May 2023 09:37:47 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:
On Saturday, May 13, 2023 at 10:55:03?AM UTC-5, John Larkin wrote:
On Sat, 13 May 2023 08:07:17 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:
On Saturday, May 13, 2023 at 8:50:52?AM UTC-5, John Larkin wrote:
On Fri, 12 May 2023 23:42:50 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:
On Friday, May 12, 2023 at 10:13:12?PM UTC-5, John Larkin wrote:

Where\'s Sloman\'s design? I really wanted to see that.

Here\'s a suggestion.

https://www.dropbox.com/s/lm7aqo3e3892hhb/6BK4_Pulser_1.jpg?raw=1

It needs to be tested and maybe tweaked. I haven\'t designed with tubes
lately.

Ahh, great John, I have been looking at grounded grid schematics, but not with your twist.
Now, I\'m waiting for parts.
I thought it was cute to have a single 6-volt power supply, but that
nails the positive grid (I keep wanting to say gate) drive at 6 too.

Whit\'s idea of push-pull drive is cute but needs another power supply,
and in its most basic form forces the + and - grid voltages to be
equal, although that is probably OK and easily fixed. One 556, the
dual 555, could drive both the grid and the cathode.

I\'m already thinking about two neon sign transformers, and another
complete tube switcher, with opposite polarity, so it will ? 7kV for a 14KV differential.

I was thinking the differential to get higher voltage, in the end I would like to have 30kV,
whether that is single sided or ? I don\'t know what is best.

The oil emulsion thing is inherently AC-coupled, no? One supply and
one tube does that.

And one neon sign transformer could make +-HV if you really wanted
that.


Would we build a negative switcher or to positives and invert the input to one?
I think Whit\'s idea is to drive the grid and cathode of the one tube,
0 and +12 maybe, antiphase. Not to have pos and neg HV.

I don\'t understand that.
Make a 0 to 12 volt positive pulse and apply it to the grid. Invert
it, still 0 to +12 but out of phase, and connect that to the cathode.
So the grid is usually -12 relative to the cathode and +12 during the
pulse. You can do it all with one NE556.

I hate the concept because I didn\'t invent it.

My suggested circuit works well making low duty cycle negative HV
pulses. Positive-going pulses would be harder.

OK, I think that is a logic thing. Since the circuit is acting to bring the output to 0V,
you are calling that negative HV pulses?
If a voltage is high positive and occasionally blips to ground, I call
that a negative pulse. Or negative-going maybe. Like the OUT here:

https://www.dropbox.com/s/lm7aqo3e3892hhb/6BK4_Pulser_1.jpg?dl=0

The tube circuit does that well. The opposite is trickier, frys the
resistors among other things.



You should build in the scope pickoff, so you can see what\'s going on.
We usually build in a signal pickoff/monitor circuit on pulsers.

Agree on that, Need to source a 1nF HV cap.
Make it!

Ya, I already looked at dielectric breakdown voltages, it seems it takes a thick dielectric.

A 1\" long copper pipe with a 0.25\" copper pipe in the center is 2pf.
If I fill it with silicone sealer (~3) I\'m up to 6pf and can shorten it considerably.
That\'s complex. I was thinking of a variant on the gimmick capacitor,
namely two pieces of insulated wire, parallel, with shrink tubing
overall. Or two layers on a PC board.

You could hack a small piece of copperclad FR4 too, and add wires. The
usual stuff is about 15 pF per square inch. You could make the entire
attenuator out of one piece of dremeled FR4!

Maybe I\'m being to concerned with arc over. I have made disc caps using Rogers 5880 (0.036\"),
using a paper punch, they are about 1.3pf. But, I think the 5880 is too thin.

If I use FR4, what is the max voltage you would go? Assumes the FR4 is larger than the copper.

Mikek

A quarter-inch square copper patch, 0.062 thick FR4, would be about 1
pF. At, say, 500 volts/mil, that\'s about 30 KV to the other side.

A clever design could be hacked onto a 1\"x2\" slab. Maybe go 10,000:1
(discrete 10 nF cap) and include a BNC to go directly to the scope.

 

[Phil Hobbs]

On 2023-05-13 17:13, John Larkin wrote:

On Sat, 13 May 2023 12:49:33 -0700 (PDT), Lamont Cranston
amdx62@gmail.com> wrote:

On Saturday, May 13, 2023 at 1:46:08?PM UTC-5, John Larkin wrote:
On Sat, 13 May 2023 09:37:47 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:
On Saturday, May 13, 2023 at 10:55:03?AM UTC-5, John Larkin wrote:
On Sat, 13 May 2023 08:07:17 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:
On Saturday, May 13, 2023 at 8:50:52?AM UTC-5, John Larkin wrote:
On Fri, 12 May 2023 23:42:50 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:
On Friday, May 12, 2023 at 10:13:12?PM UTC-5, John Larkin wrote:

Where\'s Sloman\'s design? I really wanted to see that.

Here\'s a suggestion.

https://www.dropbox.com/s/lm7aqo3e3892hhb/6BK4_Pulser_1.jpg?raw=1

It needs to be tested and maybe tweaked. I haven\'t designed with tubes
lately.

Ahh, great John, I have been looking at grounded grid schematics, but not with your twist.
Now, I\'m waiting for parts.
I thought it was cute to have a single 6-volt power supply, but that
nails the positive grid (I keep wanting to say gate) drive at 6 too.

Whit\'s idea of push-pull drive is cute but needs another power supply,
and in its most basic form forces the + and - grid voltages to be
equal, although that is probably OK and easily fixed. One 556, the
dual 555, could drive both the grid and the cathode.

I\'m already thinking about two neon sign transformers, and another
complete tube switcher, with opposite polarity, so it will ? 7kV for a 14KV differential.

I was thinking the differential to get higher voltage, in the end I would like to have 30kV,
whether that is single sided or ? I don\'t know what is best.

The oil emulsion thing is inherently AC-coupled, no? One supply and
one tube does that.

And one neon sign transformer could make +-HV if you really wanted
that.


Would we build a negative switcher or to positives and invert the input to one?
I think Whit\'s idea is to drive the grid and cathode of the one tube,
0 and +12 maybe, antiphase. Not to have pos and neg HV.

I don\'t understand that.
Make a 0 to 12 volt positive pulse and apply it to the grid. Invert
it, still 0 to +12 but out of phase, and connect that to the cathode.
So the grid is usually -12 relative to the cathode and +12 during the
pulse. You can do it all with one NE556.

I hate the concept because I didn\'t invent it.

My suggested circuit works well making low duty cycle negative HV
pulses. Positive-going pulses would be harder.

OK, I think that is a logic thing. Since the circuit is acting to bring the output to 0V,
you are calling that negative HV pulses?
If a voltage is high positive and occasionally blips to ground, I call
that a negative pulse. Or negative-going maybe. Like the OUT here:

https://www.dropbox.com/s/lm7aqo3e3892hhb/6BK4_Pulser_1.jpg?dl=0

The tube circuit does that well. The opposite is trickier, frys the
resistors among other things.



You should build in the scope pickoff, so you can see what\'s going on.
We usually build in a signal pickoff/monitor circuit on pulsers.

Agree on that, Need to source a 1nF HV cap.
Make it!

Ya, I already looked at dielectric breakdown voltages, it seems it takes a thick dielectric.

A 1\" long copper pipe with a 0.25\" copper pipe in the center is 2pf.
If I fill it with silicone sealer (~3) I\'m up to 6pf and can shorten it considerably.
That\'s complex. I was thinking of a variant on the gimmick capacitor,
namely two pieces of insulated wire, parallel, with shrink tubing
overall. Or two layers on a PC board.

You could hack a small piece of copperclad FR4 too, and add wires. The
usual stuff is about 15 pF per square inch. You could make the entire
attenuator out of one piece of dremeled FR4!

Maybe I\'m being to concerned with arc over. I have made disc caps using Rogers 5880 (0.036\"),
using a paper punch, they are about 1.3pf. But, I think the 5880 is too thin.

If I use FR4, what is the max voltage you would go? Assumes the FR4 is larger than the copper.

Mikek



A quarter-inch square copper patch, 0.062 thick FR4, would be about 1
pF. At, say, 500 volts/mil, that\'s about 30 KV to the other side.

A clever design could be hacked onto a 1\"x2\" slab. Maybe go 10,000:1
(discrete 10 nF cap) and include a BNC to go directly to the scope.

You have to worry about corona from the edges, especially if they\'re
square. I\'d be looking at ignition cable with a bit of solid wire
wrapped round it, a few inches from one end.

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

 

[Lamont Cranston]

On Saturday, May 13, 2023 at 4:43:25 PM UTC-5, Phil Hobbs wrote:

A quarter-inch square copper patch, 0.062 thick FR4, would be about 1
pF. At, say, 500 volts/mil, that\'s about 30 KV to the other side.

A clever design could be hacked onto a 1\"x2\" slab. Maybe go 10,000:1
(discrete 10 nF cap) and include a BNC to go directly to the scope.


You have to worry about corona from the edges, especially if they\'re
square. I\'d be looking at ignition cable with a bit of solid wire
wrapped round it, a few inches from one end.
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

I have a good bit of HV wire for the neon signs rated at 15kV.
I\'ll make one.
Can anyone explain why the wire is so thick in the Neon Sign Transformer wire?
The usual max current is 30ma.
Mikek

 

[Phil Hobbs]

Lamont Cranston <amdx62@gmail.com> wrote:

On Saturday, May 13, 2023 at 4:43:25 PM UTC-5, Phil Hobbs wrote:

A quarter-inch square copper patch, 0.062 thick FR4, would be about 1
pF. At, say, 500 volts/mil, that\'s about 30 KV to the other side.

A clever design could be hacked onto a 1\"x2\" slab. Maybe go 10,000:1
(discrete 10 nF cap) and include a BNC to go directly to the scope.


You have to worry about corona from the edges, especially if they\'re
square. I\'d be looking at ignition cable with a bit of solid wire
wrapped round it, a few inches from one end.
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

I have a good bit of HV wire for the neon signs rated at 15kV.
I\'ll make one.
Can anyone explain why the wire is so thick in the Neon Sign Transformer wire?
The usual max current is 30ma.
Mikek

Corona again. The field at the surface goes as 1/r.

Cheers

Phil Hobbs

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

 

[Lamont Cranston]

On Saturday, May 13, 2023 at 5:09:13 PM UTC-5, Phil Hobbs wrote:

Lamont Cranston <amd...@gmail.com> wrote:
On Saturday, May 13, 2023 at 4:43:25 PM UTC-5, Phil Hobbs wrote:

A quarter-inch square copper patch, 0.062 thick FR4, would be about 1
pF. At, say, 500 volts/mil, that\'s about 30 KV to the other side.

A clever design could be hacked onto a 1\"x2\" slab. Maybe go 10,000:1
(discrete 10 nF cap) and include a BNC to go directly to the scope.


You have to worry about corona from the edges, especially if they\'re
square. I\'d be looking at ignition cable with a bit of solid wire
wrapped round it, a few inches from one end.

5 to 6 turns of #20 wire on a 1/4\" HV wire is 1pf.