Developing HV DC Pulses...

[Anthony William Sloman]

On Monday, May 15, 2023 at 2:01:30 AM UTC+10, Lamont Cranston wrote:

On Sunday, May 14, 2023 at 10:46:45 AM UTC-5, Anthony William Sloman wrote:
On Monday, May 15, 2023 at 12:35:12 AM UTC+10, Lamont Cranston wrote:
On Sunday, May 14, 2023 at 9:20:31 AM UTC-5, Anthony William Sloman wrote:
On Monday, May 15, 2023 at 12:04:00 AM UTC+10, John Larkin wrote:
On Sun, 14 May 2023 06:27:38 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:
On Sunday, May 14, 2023 at 8:15:40?AM UTC-5, John Larkin wrote:
On Sun, 14 May 2023 05:30:59 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:
On Sunday, May 14, 2023 at 4:10:16?AM UTC-5, John Walliker wrote:
snip
If you do simple stuff fast, you\'ll learn more.

But will you learn enough? Simple stuff is a way of getting started, but to stay competitive your products have do more than the competition, or become cheaper, and you need the best product, which isn\'t necessarily the simplest.

In this thread John has been touting the high-voltage valve/tube which isn\'t all that simple to use, though it may look that way to him.

Bill, I want your input, because I\'ll soon start putting the high-voltage valve/tube pulser together, I\'d rather get it right the first time.

You won\'t. With luck you may learn enough to get something together that will work, but that\'s as much as I\'d hope for.

That\'s disheartening!

It\'s merely an opinion.

> Maybe you could post a circuit you think would get the job done.

Not one that you would find easy to put together, because I\'ve got no clear idea of what you could put together, and what you have to hand to put it together from.

I\'ve worked in university laboratories and in commercial electronic development. It\'s fairly obvious that your set-up doesn\'t look much like either.

Bigger droplets may distort into a more extended spindle/elliptical shape under the electric field, so you would expect them to move faster, but also to break up into smaller, more spherical bubbles.

There is data on small bubble chains forming (a detriment), but I will need to read again to find out why this happens.

Surface tension at the interface between body of droplet and surrounding fluid means that any non-spherical shape will tend to become more spherical.For can extended shape that can be breaking up into a string of smaller, more-nearly spherical droplets.

P.S So far we have found some of the feedstock is harder to separate then others using an electric field.

Watch out for surfactants - soaps - in the feedstock. That changes the charged double layer around the droplet that creates the charge in the first place, and messes up the surface tension that makes the droplets sort of spherical, which will changes the way the droplets will distort while being dragged along by the electric field.

The stubborn oils have got better results with de-emulsifier added.

I\'ll need to look up how de-emulsiers work.

Good idea.

--
Bill Sloman, Sydney

 

[Lamont Cranston]

On Monday, May 15, 2023 at 12:41:49 AM UTC-5, Anthony William Sloman wrote:



> > > Bigger droplets may distort into a more extended spindle/elliptical shape under the electric field, so you would expect them to move faster, but also to break up into smaller, more spherical bubbles.

Do you think Rise and Fall times of a pulse (ns vs ms) have much effect on the kinetics of the bubble coalescence?
One paper says 8 Hz is optimum, then others disagree, it may be oil type dependent.
Mikek

 

[Lamont Cranston]

On Monday, May 15, 2023 at 6:31:22 AM UTC-5, Lamont Cranston wrote:

I\'m trying to read between the lines of the Elsevier abstract quote below.

Does this read as, the experimenter is doing electric field separation with the electrodes in the emulsion?

Is there any reason you can\'t have the electrodes in solution and do electric field separation of an emulsion?

How could they change the current when the Voltage is held constant? (electrode spacing?)
Thanks, Mikek

\"As shown in Fig. 1, experiments were carried out in a laboratory scale oil treater where the direct current (DC) electric field with 60 Hz frequency was applied. The diameter and the height of the vessel containing the brass cone are 11.5 and 20 cm, respectively. The angle of the brass cone is 80° and the width of the copper strip is 8.5 cm. Water-in-oil emulsion from tank is injected into oil treater by pumping, with rotating by the centrifugal force. When emulsion droplets pass between brass
Results and discussion

Fig. 2 shows the water separation efficiency of water-in-oil emulsion as the current intensity is changed. The voltage, temperature, and residence time are kept as 5 kV, 75 °C, and 3.2 s, respectively. The current intensities are changed to 1, 2.5, 4.9 mA. The current intensity had little effect on the water separation efficiency. At the current intensity of 2.5 mA the oil treater showed the best separation efficiency of 77.2% than other current intensities.\"

 

[John Larkin]

On Mon, 15 May 2023 04:55:02 -0700 (PDT), Lamont Cranston
<amdx62@gmail.com> wrote:

On Monday, May 15, 2023 at 6:31:22?AM UTC-5, Lamont Cranston wrote:

I\'m trying to read between the lines of the Elsevier abstract quote below.

Does this read as, the experimenter is doing electric field separation with the electrodes in the emulsion?

Is there any reason you can\'t have the electrodes in solution and do electric field separation of an emulsion?

How could they change the current when the Voltage is held constant? (electrode spacing?)
Thanks, Mikek

\"As shown in Fig. 1, experiments were carried out in a laboratory scale oil treater where the direct current (DC) electric field with 60 Hz frequency was applied.

What does that mean?

 

[Phil Hobbs]

On 2023-05-14 09:03, Lamont Cranston wrote:

On Sunday, May 14, 2023 at 7:48:34 AM UTC-5, Lamont Cranston wrote:
On Sunday, May 14, 2023 at 7:31:03 AM UTC-5, Lamont Cranston wrote:
On Sunday, May 14, 2023 at 4:10:16 AM UTC-5, John Walliker wrote:

Kapton tape has much better dielectric strength and it comes with adhesive as well!
John

Looking at Kaptan tape, I find 7500V per mil, if I cover the voltage divider with a couple
of layers of Kaptan Tape will that prevent corona?
Thanks, Mikek

The voltage rating makes some assumptions about the field configuration,
i.e. that it\'s constant.

In 2-D, a corner with inside angle pi/m produces a field near the vertex
that goes as r**(1-m).

That is, an angle of pi (i.e. a straight line) produces a constant
field, an exterior right angle (pi/2) goes like 1/sqrt(r), and anything
sharper goes faster, up to 1/r.

Sharp points in 3-D produce even steeper changes in the field.

That happens in dielectrics too, so voltage rating is not the whole story.

Cheers

Phil 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]

\"As shown in Fig. 1, experiments were carried out in a laboratory scale oil treater where the direct current (DC) electric field with 60 Hz frequency was applied.
What does that mean?

My take was fullwave rectified AC without a filter capacitor.
Experiments so far have shown DC, not useful vs fullwave rectified AC.
i.e pulsed DC.

 

[Lamont Cranston]

On Monday, May 15, 2023 at 8:59:28 AM UTC-5, Lamont Cranston wrote:

\"As shown in Fig. 1, experiments were carried out in a laboratory scale oil treater where the direct current (DC) electric field with 60 Hz frequency was applied.
What does that mean?
My take was fullwave rectified AC without a filter capacitor.
Experiments so far have shown DC, not useful vs fullwave rectified AC.
i.e pulsed DC.

I take that back! The fullwave rectified DC did not produce results comparable to AC.
I\'m wondering if a rest period between pulses is helpful?
Thanks, Mikek

 

[Lamont Cranston]

Spice Model for 6BK4 in case anyone is interested in modeling the proposed circuit.
John, I\'m wondering if a much high voltage grid to cathode is need to pinch off the tube at such High Voltages?
https://www.dropbox.com/s/lm7aqo3e3892hhb/6BK4_Pulser_1.jpg?raw=1

..SUBCKT 6BK4 1 2 3 ; Plate Grid Cathode
+ PARAMS: CCG=2.6P CGP=1P CCP=1P
+ MU=2103.1 KG1=16349.49 KP=40249.51 KVB=2504.16 VCT=0.95 EX=1.4
+ VGOFF=-0.6 IGA=3.25E-4 IGB=0.18 IGC=5.76 IGEX=1.46
* Vp_MAX=25000 Ip_MAX=2.5 Vg_step=2 Vg_start=0 Vg_count=7
* Rp=4000 Vg_ac=55 P_max=40 Vg_qui=-48 Vp_qui=300
* X_MIN=104 Y_MIN=62 X_SIZE=560 Y_SIZE=446 FSZ_X=1260 FSZ_Y=727 XYGrid=true
* showLoadLine=n showIp=y isDHT=n isPP=n isAsymPP=n showDissipLimit=y
* showIg1=y gridLevel2=y isInputSnapped=n
* XYProjections=n harmonicPlot=n dissipPlot=n
*----------------------------------------------------------------------------------
E1 7 0 VALUE={V(1,3)/KP*LOG(1+EXP(KP*(1/MU+(VCT+V(2,3))/SQRT(KVB+V(1,3)*V(1,3)))))}
RE1 7 0 1G ; TO AVOID FLOATING NODES
G1 1 3 VALUE={(PWR(V(7),EX)+PWRS(V(7),EX))/KG1}
RCP 1 3 1G ; TO AVOID FLOATING NODES
C1 2 3 {CCG} ; CATHODE-GRID
C2 2 1 {CGP} ; GRID=PLATE
C3 1 3 {CCP} ; CATHODE-PLATE
RE2 2 0 1G
EGC 8 0 VALUE={V(2,3)-VGOFF} ; POSITIVE GRID THRESHOLD
GG 2 3 VALUE={(IGA+IGB/(IGC+V(1,3)))*(MU/KG1)*(PWR(V(8),IGEX)+PWRS(V(8),IGEX))}
..ENDS
*$

 

[John Larkin]

On Mon, 15 May 2023 08:15:37 -0700 (PDT), Lamont Cranston
<amdx62@gmail.com> wrote:

Spice Model for 6BK4 in case anyone is interested in modeling the proposed circuit.
John, I\'m wondering if a much high voltage grid to cathode is need to pinch off the tube at such High Voltages?
https://www.dropbox.com/s/lm7aqo3e3892hhb/6BK4_Pulser_1.jpg?raw=1

Once the mosfet is off, the tube pinches itself off. Wild guess, the
cathode might pull itself up to +15.

My -----* suggests that a zener or something might be needed to
protect the mosfet, but probably not.

The tube data sheet is not adequate to this application, so the tube
should be tested. I wouldn\'t entitely trust the Spice model either.
There\'s no heater!

.SUBCKT 6BK4 1 2 3 ; Plate Grid Cathode
+ PARAMS: CCG=2.6P CGP=1P CCP=1P
+ MU=2103.1 KG1=16349.49 KP=40249.51 KVB=2504.16 VCT=0.95 EX=1.4
+ VGOFF=-0.6 IGA=3.25E-4 IGB=0.18 IGC=5.76 IGEX=1.46
* Vp_MAX=25000 Ip_MAX=2.5 Vg_step=2 Vg_start=0 Vg_count=7
* Rp=4000 Vg_ac=55 P_max=40 Vg_qui=-48 Vp_qui=300
* X_MIN=104 Y_MIN=62 X_SIZE=560 Y_SIZE=446 FSZ_X=1260 FSZ_Y=727 XYGrid=true
* showLoadLine=n showIp=y isDHT=n isPP=n isAsymPP=n showDissipLimit=y
* showIg1=y gridLevel2=y isInputSnapped=n
* XYProjections=n harmonicPlot=n dissipPlot=n
*----------------------------------------------------------------------------------
E1 7 0 VALUE={V(1,3)/KP*LOG(1+EXP(KP*(1/MU+(VCT+V(2,3))/SQRT(KVB+V(1,3)*V(1,3)))))}
RE1 7 0 1G ; TO AVOID FLOATING NODES
G1 1 3 VALUE={(PWR(V(7),EX)+PWRS(V(7),EX))/KG1}
RCP 1 3 1G ; TO AVOID FLOATING NODES
C1 2 3 {CCG} ; CATHODE-GRID
C2 2 1 {CGP} ; GRID=PLATE
C3 1 3 {CCP} ; CATHODE-PLATE
RE2 2 0 1G
EGC 8 0 VALUE={V(2,3)-VGOFF} ; POSITIVE GRID THRESHOLD
GG 2 3 VALUE={(IGA+IGB/(IGC+V(1,3)))*(MU/KG1)*(PWR(V(8),IGEX)+PWRS(V(8),IGEX))}
.ENDS
*$

 

[Lamont Cranston]

On Monday, May 15, 2023 at 10:53:14 AM UTC-5, John Larkin wrote:

On Mon, 15 May 2023 08:15:37 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:

Spice Model for 6BK4 in case anyone is interested in modeling the proposed circuit.
John, I\'m wondering if a much high voltage grid to cathode is need to pinch off the tube at such High Voltages?
https://www.dropbox.com/s/lm7aqo3e3892hhb/6BK4_Pulser_1.jpg?raw=1
Once the mosfet is off, the tube pinches itself off. Wild guess, the
cathode might pull itself up to +15.

My -----* suggests that a zener or something might be needed to
protect the mosfet, but probably not.

The tube data sheet is not adequate to this application, so the tube
should be tested. I wouldn\'t entitely trust the Spice model either.
There\'s no heater!

OK, waiting on parts.
Mikek

 

[Arie de Muijnck]

On 2023-05-15 16:40, Lamont Cranston wrote:

On Monday, May 15, 2023 at 8:59:28 AM UTC-5, Lamont Cranston wrote:
\"As shown in Fig. 1, experiments were carried out in a laboratory scale oil treater where the direct current (DC) electric field with 60 Hz frequency was applied.
What does that mean?
My take was fullwave rectified AC without a filter capacitor.
Experiments so far have shown DC, not useful vs fullwave rectified AC.
i.e pulsed DC.

I take that back! The fullwave rectified DC did not produce results comparable to AC.
I\'m wondering if a rest period between pulses is helpful?
Thanks, Mikek

That would match with the \'DC 60 Hz\' which is obtained by half-wave rectification.

Arie

 

[Phil Hobbs]

On 2023-05-15 11:53, John Larkin wrote:

On Mon, 15 May 2023 08:15:37 -0700 (PDT), Lamont Cranston
amdx62@gmail.com> wrote:

Spice Model for 6BK4 in case anyone is interested in modeling the proposed circuit.
John, I\'m wondering if a much high voltage grid to cathode is need to pinch off the tube at such High Voltages?
https://www.dropbox.com/s/lm7aqo3e3892hhb/6BK4_Pulser_1.jpg?raw=1

Once the mosfet is off, the tube pinches itself off. Wild guess, the
cathode might pull itself up to +15.

My -----* suggests that a zener or something might be needed to
protect the mosfet, but probably not.

The tube data sheet is not adequate to this application, so the tube
should be tested. I wouldn\'t entitely trust the Spice model either.
There\'s no heater!

Weird things can happen at very high voltages, e.g. the shielding
effectiveness of the grid isn\'t really 100%, so the cathode current
probably won\'t cut off altogether.

A small zener might be an excellent idea.

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]

That would match with the \'DC 60 Hz\' which is obtained by half-wave rectification.

Arie

Hmm, we were about ready to try halfwave rectification and my son went a different route.
I like the rest period between halfwave pulse, but don\'t know if it matters.
Also, that could have been a mistake 60Hz of 120Hz from fuel scientists!
Mikek

 

[Lamont Cranston]

On Monday, May 15, 2023 at 12:22:50 PM UTC-5, Lamont Cranston wrote:

I think I need to add some safety,
Can I ground the aluminum tube as shown in this drawing?
Would it create an unwanted potential between the primary and secondary?
https://www.dropbox.com/s/nh1qoea3um39n30/OiL%20water%20Vessel%20Adding%20GRD%20to%20the%20aluminum%20Vessel..jpg?dl=0


Thanks, Mikek

 

[John Larkin]

On Mon, 15 May 2023 12:59:00 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2023-05-15 11:53, John Larkin wrote:
On Mon, 15 May 2023 08:15:37 -0700 (PDT), Lamont Cranston
amdx62@gmail.com> wrote:

Spice Model for 6BK4 in case anyone is interested in modeling the proposed circuit.
John, I\'m wondering if a much high voltage grid to cathode is need to pinch off the tube at such High Voltages?
https://www.dropbox.com/s/lm7aqo3e3892hhb/6BK4_Pulser_1.jpg?raw=1

Once the mosfet is off, the tube pinches itself off. Wild guess, the
cathode might pull itself up to +15.

My -----* suggests that a zener or something might be needed to
protect the mosfet, but probably not.

The tube data sheet is not adequate to this application, so the tube
should be tested. I wouldn\'t entitely trust the Spice model either.
There\'s no heater!


Weird things can happen at very high voltages, e.g. the shielding
effectiveness of the grid isn\'t really 100%, so the cathode current
probably won\'t cut off altogether.

A small zener might be an excellent idea.

Cheers

Phil Hobbs

If the mosfet is open, where would any plate current go? But even a
couple of uA wouldn\'t be a problem here.

There will certainly be some conduction between the cathode and the
filament.

I guess the cathode could, maybe, rise to 100 volts or something, so a
24v zener to ground might be prudent.

Tube books don\'t usually address these subtelties.

 

[ehsjr]

On 5/14/2023 9:27 AM, Lamont Cranston wrote:

On Sunday, May 14, 2023 at 8:15:40 AM UTC-5, John Larkin wrote:
On Sun, 14 May 2023 05:30:59 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:
On Sunday, May 14, 2023 at 4:10:16?AM UTC-5, John Walliker wrote:

Kapton tape has much better dielectric strength and it comes with adhesive as well!
John

My son caught my mistake with a 4 output voltage divider using 4kV and 8kV. I was thinking,
1kV, 2kV, 3kv, and 4kv, and second test at 8kV output 5kV, 6kV, 7kV and 8kV.,
But the second test is 2kV, 4kV, 6kV and 8kV, not what we want.
So he wants 8 outputs, 1kV thru 8kV in 1kV steps.
He wants to use banana plugs for quick change.
Can we get away with this?
https://www.dropbox.com/s/dcjs0aon4zgxplw/Oil%20Water%208%20output%20Voltage%20Divider%20with%20Banana%20Connectors.jpg?dl=0
Would it help to cover the Resistor divider with a few layers of Kaptan tape?
Thanks, Mikek
Put a row of banana jacks on a piece of plastic. Solder the resistors
between the jacks the obvious way. Ordinary banana leads can run out
to the cells. Ignore corona. It\'s only an experiment and it\'s only
8KV.

Amazon has great banana jack assortments.

https://www.amazon.com/gp/product/B07KCRMV4V/

https://www.amazon.com/gp/product/B01CJDGWRU

These are cool on PC boards too.

John, I\'ll take that under advisement, however,
there could come a point in experiments, that I add a second transformer
and go up to 18kV or even 30kV. When we go to a larger diameter vessel,
the electric field per cm goes down, to compensate our input voltage needs to go up.
I\'m now hopefully going to start spending someone else\'s money on parts, so I have less concern.
I\'d like to build for possible future developments.
What about kaptan tape over the Resistive divider, does that help prevent corona?
Mikek

Construction technique is the first thing to address concerning
HV corona. No sharp points, no 90 degree bends, proper spacing
etc. As a kind of double check - if it looks ugly it\'s probably
bad HV construction. Either Kapton or teflon tape properly
used is fine. Depends on what you\'ve got on hand/ find easier
to use/cost & availability considerations, etc. But don\'t rely
on the tape to make up for bad construction. With the first
proposal - a 1/4\" center conductor inside an outer pipe, wrapping
the center conductor with teflon tape for a snug fit is almost
a \"no-brainer\" for getting the construction right. Where the
string of 1.5meg resistors is concerned, there\'s a lot more
chance of sharp points, sag, bent wires etc.

Ed

P.S. adding in my ignorance about HV projects, I\'d rather err on the side of gross overkill!

 

[Lamont Cranston]

On Monday, May 15, 2023 at 2:51:32 PM UTC-5, ehsjr wrote:

What about kaptan tape over the Resistive divider, does that help prevent corona?
Mikek

Construction technique is the first thing to address concerning
HV corona. No sharp points, no 90 degree bends, proper spacing
etc. As a kind of double check - if it looks ugly it\'s probably
bad HV construction. Either Kapton or teflon tape properly
used is fine. Depends on what you\'ve got on hand/ find easier
to use/cost & availability considerations, etc. But don\'t rely
on the tape to make up for bad construction. With the first
proposal - a 1/4\" center conductor inside an outer pipe, wrapping
the center conductor with teflon tape for a snug fit is almost
a \"no-brainer\" for getting the construction right. Where the
string of 1.5meg resistors is concerned, there\'s a lot more
chance of sharp points, sag, bent wires etc.

Ed

OK, thanks for that. I suspect first iteration will just be the resistor soldered as fat as possible with sharp points.
But, if/when needed, I might try the brass tube idea. I have shown it here under the big red arrow!
https://www.dropbox.com/s/nnulb0dvw36a9pa/Oil%20Water%208%20output%20Voltage%20Divider%20with%20Banana%20Connectors%20Corona%20Modification.jpg?dl=0
I haven\'t solved how I\'d attach the brass rod to the threaded post sticking out of the banana jack. Maybe a thru hole and put the nut
on, if the threaded rod is long enough. Future developments.
Thanks, Mikek

 

[Lamont Cranston]

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

 

[Lamont Cranston]

On Monday, May 15, 2023 at 5:56:28 PM UTC-5, Lamont Cranston wrote:

I\'m wondering if fast edges are important, can a water bubble move through an emulsion the needed distance
as fast as the rise time of a fast pulse!
Ya, I know (needed) distance and (fast) pulse are unknowns.
I\'ve been concerned about rise and fall times, now wondering if it is less important.
May even be, a fast rise time could be wasted because the water bubble has no time to get moving, before the pulse is steady state.
Several papers say action only happens on rise and fall.

Thanks, Mikek

 

[Anthony William Sloman]

On Tuesday, May 16, 2023 at 9:05:33 AM UTC+10, Lamont Cranston wrote:

On Monday, May 15, 2023 at 5:56:28 PM UTC-5, Lamont Cranston wrote:

I\'m wondering if fast edges are important, can a water bubble move through an emulsion the needed distance as fast as the rise time of a fast pulse!

A water bubble won\'t move fast at all. Your de-emulsifying station will have to move the fluid past the electronces so that there are always a few droplets close to the electrode when the electric field is high enough to move them onto it.

This probably explains why you need a pulsed field - dirt and gunge in the fluid getting de-emulsified will also get stuck to the electrodes and will get stuck tighter than the water droplets. If you turn off the electric field some of the time, the stirring of the fluid will move the gunge away from the electrode far enough to let new water droplets in so that they can coalesce on the electrode when the field comes back.

Ya, I know (needed) distance and (fast) pulse are unknowns. I\'ve been concerned about rise and fall times, now wondering if it is less important.
May even be, a fast rise time could be wasted because the water bubble has no time to get moving, before the pulse is steady state.
Several papers say action only happens on rise and fall.

If you leave the voltage on for long enough to let all the gunge get stuck onto the electrodes, it will block the water droplets

--
Bill Sloman, Sydney