Developing HV DC Pulses...

  • Thread starter Lamont Cranston
  • Start date
On Sun, 28 May 2023 09:44:41 -0700, John Larkin wrote:

On Sun, 28 May 2023 05:16:56 -0700 (PDT), Lamont Cranston
amdx62@gmail.com> wrote:

On Sunday, May 28, 2023 at 6:10:50?AM UTC-5, Glen Walpert wrote:
On Sat, 27 May 2023 11:25:00 -0700, John Larkin wrote:

On Sat, 27 May 2023 10:52:16 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:

On Saturday, May 27, 2023 at 11:24:07?AM UTC-5, Glen Walpert wrote:

Your bridge uses 4 diodes. A half-wave doubler would use two.
The bridge is not usable for producing a ground referenced HVDC from a
transformer with a grounded secondary, but full wave rectification is
possible with 2 diodes from a center tapped transformer with a single
diode in each transformer HV to the filter cap, return to grounded CT.
This gives you full wave rectification at half voltage. Substitute a
half wave doubler for both diodes to get back to full voltage, still
ground referenced.

Hi Glen, I\'m not sure how to draw what you describe, but I found
this, that uses the earth grounded
CT as the negative lead of the HV. I think this solves the
Neutral/ground problem.
Is this what you described?
https://www.dropbox.com/s/c4t13kzi62txwqo/Centertapped%20Doubler.jpg?
dl=0
Thanks, Mikek

You don\'t really need the bottom half; your load current will be low.
Click to expand...

Yes, that\'s it. It does solve the ground problem, but like John says you
probably don\'t need the bottom half, which would double the available
current at the same voltage. Your neutral/ground problem will be solved
either way.
 
On Sunday, May 28, 2023 at 3:11:36 PM UTC-5, Glen Walpert wrote:

You don\'t really need the bottom half; your load current will be low.
Yes, that\'s it. It does solve the ground problem, but like John says you
probably don\'t need the bottom half, which would double the available
current at the same voltage. Your neutral/ground problem will be solved
either way.
Click to expand...

I did some measurements using 3.1nF caps that had no voltage label, they came off a CW multiplier with 8kV diodes.
So, they probably didn\'t meet the Voltage I put across them with the doubler suggested. It all worked OK at 5kV and 1ma load.
But I pushed it to 8kV where one of the caps arced, so I\'m done until an Amazon delivery today of some 20kV 4.7nF caps.
It\'s looking promising, but I want to find out the droop under load with 4..7nF caps.
Mikek
 
On Monday, May 29, 2023 at 8:58:33 AM UTC-5, Lamont Cranston wrote:
On Sunday, May 28, 2023 at 3:11:36 PM UTC-5, Glen Walpert wrote:

You don\'t really need the bottom half; your load current will be low.
Yes, that\'s it. It does solve the ground problem, but like John says you
probably don\'t need the bottom half, which would double the available
current at the same voltage. Your neutral/ground problem will be solved
either way.
I did some measurements using 3.1nF caps that had no voltage label, they came off a CW multiplier with 8kV diodes.
So, they probably didn\'t meet the Voltage I put across them with the doubler suggested. It all worked OK at 5kV and 1ma load.
But I pushed it to 8kV where one of the caps arced, so I\'m done until an Amazon delivery today of some 20kV 4.7nF caps.
It\'s looking promising, but I want to find out the droop under load with 4.7nF caps.
Mikek
Click to expand...

Arrgh! I\'m pretty far in and realize the setup we have has a 12MΩ load, The proposed 10MΩ dropping resistor going to the tube
will reduce the output to 4.4kV. I could increase the resistors in the 8 resistor voltage divider, but the risetime with 20pf per vessel
is already 250us, worst case. I can lower the 10MΩ dropping resistor to 6MΩ and raise the voltage to 12kV to get back to the desired 8kV.
That does push the limit of tubes 1.6ma average current, but if we don\'t go over 50% duty cycle, I\'m thinking it\'s still OK.
Your thoughts?
Also, Can this be made into a tripler and quadrupler?
https://www.dropbox.com/s/c4t13kzi62txwqo/Centertapped%20Doubler.jpg?dl=0
I have searched and don\'t see any that use the CT as reference.
Thanks, Mikek
 
On Tuesday, May 30, 2023 at 3:05:04 PM UTC-4, Lamont Cranston wrote:

Can this be made into a tripler and quadrupler?
https://www.dropbox.com/s/c4t13kzi62txwqo/Centertapped%20Doubler.jpg?dl=0
I have searched and don\'t see any that use the CT as reference.
Click to expand...

That\'s just the first stage of a Cockcroft-Walton multiplier; the \'CT as a reference\'
is ambiguous; your center tap on the secondary is ground, and the symmetric
ladder will generate (+) and (-) legs, which could be applied to two
HV electrodes to do the electrophoresis (alas, the switching of the negative leg
isn\'t trivial with your vacuum tube).
 
On Wed, 31 May 2023 05:20:49 -0700 (PDT), whit3rd <whit3rd@gmail.com>
wrote:

On Tuesday, May 30, 2023 at 3:05:04?PM UTC-4, Lamont Cranston wrote:

Can this be made into a tripler and quadrupler?
https://www.dropbox.com/s/c4t13kzi62txwqo/Centertapped%20Doubler.jpg?dl=0
I have searched and don\'t see any that use the CT as reference.

That\'s just the first stage of a Cockcroft-Walton multiplier; the \'CT as a reference\'
is ambiguous; your center tap on the secondary is ground, and the symmetric
ladder will generate (+) and (-) legs, which could be applied to two
HV electrodes to do the electrophoresis (alas, the switching of the negative leg
isn\'t trivial with your vacuum tube).
Click to expand...

There are *so* many ways to make a simple thing hard.
 
On Thursday, June 1, 2023 at 12:03:00 AM UTC+10, John Larkin wrote:
On Wed, 31 May 2023 05:20:49 -0700 (PDT), whit3rd <whi...@gmail.com
wrote:
On Tuesday, May 30, 2023 at 3:05:04?PM UTC-4, Lamont Cranston wrote:

Can this be made into a tripler and quadrupler?
https://www.dropbox.com/s/c4t13kzi62txwqo/Centertapped%20Doubler.jpg?dl=0
I have searched and don\'t see any that use the CT as reference.

That\'s just the first stage of a Cockcroft-Walton multiplier; the \'CT as a reference\'
is ambiguous; your center tap on the secondary is ground, and the symmetric
ladder will generate (+) and (-) legs, which could be applied to two
HV electrodes to do the electrophoresis (alas, the switching of the negative leg
isn\'t trivial with your vacuum tube).
Click to expand...

Why bother. A Cockcroft-Walton multipler driven by a fast oscillator - 10kHz to 100kHz - can charge up and discharge fast enough to deliver the on and off times that Mirek wants without any fancy switching.

> There are *so* many ways to make a simple thing hard.

And so many ways to screw up if you don\'t bother to understand what you are doing and skimp on the detailed design.

--
Bill Sloman, Sydney
 
OK, I have a double sided tripler working, (although low volts, 5Vac in 15vdc out)
I don\'t get all the ripple? Here are the wave forms of each side independent and loaded. The second picture is with the diode on the right side connected and all the load moved to the upper side and center tap/NEG. The voltage does go up, i.e. it will supply more current. I thought the ripple would be reduced, it is actually increased. Any thoughts?
https://www.dropbox.com/s/llmeeya2s47iwm2/Voltage%20trippler%20doublesidded%20waveforms..jpg?dl=0

Thanks, Mikek

P.S, guys remember, I\'m the fishmonger, I\'m doing the best I can with what knowledge I have.
I don\'t want to take the time to develop a high frequency supply, and I probably don\'t have the ability.
John, \"There are *so* many ways to make a simple thing hard.\"
I don\'t know what you are addressing, Is it the double sided tripler? I may not need it, but I\'m close on getting the 12kV.
Or is it the 12MΩ load requiring a higher input voltage? After experiments, we may be able to reduce this to one vessel, but
for now we want 4 vessels run at 4 increasing voltages.
 
On Wednesday, May 31, 2023 at 10:19:04 AM UTC-5, Lamont Cranston wrote:
OK, I have a double sided tripler working, (although low volts, 5Vac in 15vdc out)
I don\'t get all the ripple? Here are the wave forms of each side independent and loaded. The second picture is with the diode on the right side connected and all the load moved to the upper side and center tap/NEG. The voltage does go up, i.e. it will supply more current. I thought the ripple would be reduced, it is actually increased. Any thoughts?
https://www.dropbox.com/s/llmeeya2s47iwm2/Voltage%20trippler%20doublesidded%20waveforms..jpg?dl=0

Thanks, Mikek

P.S, guys remember, I\'m the fishmonger, I\'m doing the best I can with what knowledge I have.
I don\'t want to take the time to develop a high frequency supply, and I probably don\'t have the ability.
John, \"There are *so* many ways to make a simple thing hard.\"
I don\'t know what you are addressing, Is it the double sided tripler? I may not need it, but I\'m close on getting the 12kV.
Or is it the 12MΩ load requiring a higher input voltage? After experiments, we may be able to reduce this to one vessel, but
for now we want 4 vessels run at 4 increasing voltages.
Click to expand...

Forgot to add the doubler schematic.
https://www.dropbox.com/s/g8fmf4m5n44jlq4/Voltage%20Tripler%20both%20sides%20of%20Center%20Tap.jpg?dl=0

Mikek
 
On Wed, 31 May 2023 09:17:20 -0700 (PDT), Lamont Cranston
<amdx62@gmail.com> wrote:

On Wednesday, May 31, 2023 at 10:19:04?AM UTC-5, Lamont Cranston wrote:
OK, I have a double sided tripler working, (although low volts, 5Vac in 15vdc out)
I don\'t get all the ripple? Here are the wave forms of each side independent and loaded. The second picture is with the diode on the right side connected and all the load moved to the upper side and center tap/NEG. The voltage does go up, i.e. it will supply more current. I thought the ripple would be reduced, it is actually increased. Any thoughts?
https://www.dropbox.com/s/llmeeya2s47iwm2/Voltage%20trippler%20doublesidded%20waveforms..jpg?dl=0

Thanks, Mikek

P.S, guys remember, I\'m the fishmonger, I\'m doing the best I can with what knowledge I have.
I don\'t want to take the time to develop a high frequency supply, and I probably don\'t have the ability.
John, \"There are *so* many ways to make a simple thing hard.\"
I don\'t know what you are addressing, Is it the double sided tripler? I may not need it, but I\'m close on getting the 12kV.
Or is it the 12M? load requiring a higher input voltage? After experiments, we may be able to reduce this to one vessel, but
for now we want 4 vessels run at 4 increasing voltages.

Forgot to add the doubler schematic.
https://www.dropbox.com/s/g8fmf4m5n44jlq4/Voltage%20Tripler%20both%20sides%20of%20Center%20Tap.jpg?dl=0

Mikek
Click to expand...

Does that make 3Vp?
 
On Wednesday, May 31, 2023 at 11:22:25 AM UTC-5, John Larkin wrote:
On Wed, 31 May 2023 09:17:20 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:
On Wednesday, May 31, 2023 at 10:19:04?AM UTC-5, Lamont Cranston wrote:
OK, I have a double sided tripler working, (although low volts, 5Vac in 15vdc out)
I don\'t get all the ripple? Here are the wave forms of each side independent and loaded. The second picture is with the diode on the right side connected and all the load moved to the upper side and center tap/NEG. The voltage does go up, i.e. it will supply more current. I thought the ripple would be reduced, it is actually increased. Any thoughts?
https://www.dropbox.com/s/llmeeya2s47iwm2/Voltage%20trippler%20doublesidded%20waveforms..jpg?dl=0

Thanks, Mikek

P.S, guys remember, I\'m the fishmonger, I\'m doing the best I can with what knowledge I have.
I don\'t want to take the time to develop a high frequency supply, and I probably don\'t have the ability.
John, \"There are *so* many ways to make a simple thing hard.\"
I don\'t know what you are addressing, Is it the double sided tripler? I may not need it, but I\'m close on getting the 12kV.
Or is it the 12M? load requiring a higher input voltage? After experiments, we may be able to reduce this to one vessel, but
for now we want 4 vessels run at 4 increasing voltages.

Forgot to add the doubler schematic.
https://www.dropbox.com/s/g8fmf4m5n44jlq4/Voltage%20Tripler%20both%20sides%20of%20Center%20Tap.jpg?dl=0

Mikek
Does that make 3Vp?
Click to expand...

No sorry, left over from copying the schematic.
5Vac in 16.8vdc out, 2.8kΩ load
Waveform below.
https://www.dropbox.com/s/94dsuq92nl9ehmg/xxzz.jpg?dl=0
Thanks, Mikek
 
On Wednesday, May 31, 2023 at 12:24:38 PM UTC-5, Lamont Cranston wrote:

No sorry, left over from copying the schematic.
5Vac in 16.8vdc out, 2.8kΩ load
Waveform below.
https://www.dropbox.com/s/94dsuq92nl9ehmg/xxzz.jpg?dl=0
Thanks, Mikek
Click to expand...

Ah, simple output cap, I tried that earlier, but it killed the output, I expect
i had it misplaced.
Mikek
 
I have a 6kV input, as initial test.
I\'m using a 2.5MΩ dropping resistor an a 4.5MΩ load.
That voltage divider gives me 3,844V on the plate.
When the grid is energized I get a 3,678V pulse riding on 166Vdc.
About 1.5ma through the tube.

Still need some additional parts to finish the tripler and I need to
put a 30 watt 6MΩ resistor together. I\'ll see what I can get, I can probably
get by with 20 watt, but I\'d rather run it cool.

Thanks for all the help I was given to get this up and running.

Mikek
 
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