Help with a voltage multiplier...

[Lamont Cranston]

In my junque box I have a High Voltage, Voltage multiplier.
I pulled it out to help my son on a project and it doesn\'t work as I expected.
Testing of the parts tells me they are all good. But the voltages don\'t seem right. I\'m using a Bryman 235 DVM with a 10MΩ input impedance. So, I\'m don\'t expect I\'m loading the circuit.
I took a picture and put voltage reads on the picture with some info about the diodes and caps. The diodes are about 1\" long and have a 10v drop at 2ma.
I would like to know the voltage ratings of the diodes and caps, but don\'t
find any info on the net.
Any Idea, why my voltages are way off?
Mikek

https://www.dropbox.com/s/ox8xomn4aiutprf/HV%20Multiplier.jpg?dl=0

 

[John Larkin]

On Mon, 1 May 2023 18:55:11 -0700 (PDT), Lamont Cranston
<amdx62@gmail.com> wrote:

In my junque box I have a High Voltage, Voltage multiplier.
I pulled it out to help my son on a project and it doesn\'t work as I expected.
Testing of the parts tells me they are all good. But the voltages don\'t seem right. I\'m using a Bryman 235 DVM with a 10M? input impedance. So, I\'m don\'t expect I\'m loading the circuit.
I took a picture and put voltage reads on the picture with some info about the diodes and caps. The diodes are about 1\" long and have a 10v drop at 2ma.
I would like to know the voltage ratings of the diodes and caps, but don\'t
find any info on the net.
Any Idea, why my voltages are way off?
Mikek

https://www.dropbox.com/s/ox8xomn4aiutprf/HV%20Multiplier.jpg?dl=0

What frequency is your AC source?

It would be easy to measure the caps. Then teach the kid about Spice.

 

[Lamont Cranston]

On Monday, May 1, 2023 at 10:03:45 PM UTC-5, John Larkin wrote:

On Mon, 1 May 2023 18:55:11 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:

In my junque box I have a High Voltage, Voltage multiplier.
I pulled it out to help my son on a project and it doesn\'t work as I expected.
Testing of the parts tells me they are all good. But the voltages don\'t seem right. I\'m using a Bryman 235 DVM with a 10M? input impedance. So, I\'m don\'t expect I\'m loading the circuit.
I took a picture and put voltage reads on the picture with some info about the diodes and caps. The diodes are about 1\" long and have a 10v drop at 2ma.
I would like to know the voltage ratings of the diodes and caps, but don\'t
find any info on the net.
Any Idea, why my voltages are way off?
Mikek

https://www.dropbox.com/s/ox8xomn4aiutprf/HV%20Multiplier.jpg?dl=0
What frequency is your AC source?

It would be easy to measure the caps. Then teach the kid about Spice.

60 Hz, I did measure the caps, 3.1nF.
Just need HVDC for a project, I thought this would be helpful, but it\'s not working as I expected.
I have HV transformer, just wanted to use this to get DC.
Mikek

 

[John Larkin]

On Mon, 1 May 2023 20:12:17 -0700 (PDT), Lamont Cranston
<amdx62@gmail.com> wrote:

On Monday, May 1, 2023 at 10:03:45?PM UTC-5, John Larkin wrote:
On Mon, 1 May 2023 18:55:11 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:

In my junque box I have a High Voltage, Voltage multiplier.
I pulled it out to help my son on a project and it doesn\'t work as I expected.
Testing of the parts tells me they are all good. But the voltages don\'t seem right. I\'m using a Bryman 235 DVM with a 10M? input impedance. So, I\'m don\'t expect I\'m loading the circuit.
I took a picture and put voltage reads on the picture with some info about the diodes and caps. The diodes are about 1\" long and have a 10v drop at 2ma.
I would like to know the voltage ratings of the diodes and caps, but don\'t
find any info on the net.
Any Idea, why my voltages are way off?
Mikek

https://www.dropbox.com/s/ox8xomn4aiutprf/HV%20Multiplier.jpg?dl=0
What frequency is your AC source?

It would be easy to measure the caps. Then teach the kid about Spice.

60 Hz, I did measure the caps, 3.1nF.
Just need HVDC for a project, I thought this would be helpful, but it\'s not working as I expected.
I have HV transformer, just wanted to use this to get DC.
Mikek

At 60 Hz, each cap is about 800K ohms.

The mult was probably intended for high frequency drive.

 

[Lamont Cranston]

On Monday, May 1, 2023 at 10:27:14 PM UTC-5, John Larkin wrote:

On Mon, 1 May 2023 20:12:17 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:
On Monday, May 1, 2023 at 10:03:45?PM UTC-5, John Larkin wrote:
On Mon, 1 May 2023 18:55:11 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:

In my junque box I have a High Voltage, Voltage multiplier.
I pulled it out to help my son on a project and it doesn\'t work as I expected.
Testing of the parts tells me they are all good. But the voltages don\'t seem right. I\'m using a Bryman 235 DVM with a 10M? input impedance. So, I\'m don\'t expect I\'m loading the circuit.
I took a picture and put voltage reads on the picture with some info about the diodes and caps. The diodes are about 1\" long and have a 10v drop at 2ma.
I would like to know the voltage ratings of the diodes and caps, but don\'t
find any info on the net.
Any Idea, why my voltages are way off?
Mikek

https://www.dropbox.com/s/ox8xomn4aiutprf/HV%20Multiplier.jpg?dl=0
What frequency is your AC source?

It would be easy to measure the caps. Then teach the kid about Spice.

60 Hz, I did measure the caps, 3.1nF.
Just need HVDC for a project, I thought this would be helpful, but it\'s not working as I expected.
I have HV transformer, just wanted to use this to get DC.
Mikek
At 60 Hz, each cap is about 800K ohms.

The mult was probably intended for high frequency drive.

Oh, I hadn\'t thought about that. I thought it came with some ham radio junque and just assumed it was 60 hertz.
Now I wonder what its original use was? Also why I can\'t find data on the diode.
Thanks, Mikek

 

[Phil Allison]

Lamont Cranston wrote:
-----------------------------------------

At 60 Hz, each cap is about 800K ohms.

The mult was probably intended for high frequency drive.


Oh, I hadn\'t thought about that. I thought it came with some ham radio junque and just assumed it was 60 hertz.
Now I wonder what its original use was?

** May well be 60Hz drive, if meant for use with an electrostatic tweeter.
The component values and number of stages looks right for that app.

>Also why I can\'t find data on the diode.

** Might be way obsolete types.
Expect them to be rated at 10kV or more with very low leakage.

FYI: Such multipliers cannot be tested with a regular DMM alone.
Needs a high voltage probe, with at least 1000 Mohms resistance.




....... Phil

 

[Phil Allison]

Lamont Cranston wrote:

-------------------------------------

Oh, I hadn\'t thought about that. I thought it came with some ham radio junque and just assumed it was 60 hertz.
Now I wonder what its original use was? Also why I can\'t find data on the diode.

** FYI:

Only one diode has EDI 7712 on it - the other 7 are all labelled EDI 7711.
It\'s a DATE code, 11th or 12th week of 1977 !!.

The maker of the RHC8-5 is \"American Microsemiconductor\".
See vid: https://www.youtube.com/watch?v=JnpprGFAmpQ




........ Phil

 

[Matthias Czech]

Am 02.05.2023 um 09:04 schrieb Phil Allison:

Lamont Cranston wrote:

-------------------------------------
Oh, I hadn\'t thought about that. I thought it came with some ham radio junque and just assumed it was 60 hertz.
Now I wonder what its original use was? Also why I can\'t find data on the diode.


** FYI:

Only one diode has EDI 7712 on it - the other 7 are all labelled EDI 7711.
It\'s a DATE code, 11th or 12th week of 1977 !!.

The maker of the RHC8-5 is \"American Microsemiconductor\".
See vid: https://www.youtube.com/watch?v=JnpprGFAmpQ

Maybe EDI stands for this company:
http://www.e-edi.com/index.php

They have a RHC25-8
http://www.e-edi.com/pdf/HiVoltage/LHC_RHC.PDF

 

[Phil Allison]

Matthias Czech wrote:
--------------------------------------
Phil Allison:

Lamont Cranston wrote:

-------------------------------------
Oh, I hadn\'t thought about that. I thought it came with some ham radio junque and just assumed it was 60 hertz.
Now I wonder what its original use was? Also why I can\'t find data on the diode.


** FYI:

Only one diode has EDI 7712 on it - the other 7 are all labelled EDI 7711.
It\'s a DATE code, 11th or 12th week of 1977 !!.

The maker of the RHC8-5 is \"American Microsemiconductor\".
See vid: https://www.youtube.com/watch?v=JnpprGFAmpQ


Maybe EDI stands for this company:
http://www.e-edi.com/index.php

** OK - EDI make or supply the same number diode with their initials on it.

They have a RHC25-8
http://www.e-edi.com/pdf/HiVoltage/LHC_RHC.PDF

** Going on that example, the OP\'s diode is a fast, 5mA, 8kV type.
All fits with the idea it supplies only a tiny (uA) current from a 60Hz supply.

An electrostatic tweeter, from the late \'70s, is still a likely use for the multiplier.
The molded ABS mounting plate is big clue too.

..... Phil

 

[Chris Jones]

On 2/05/2023 6:04 pm, Phil Allison wrote:

Matthias Czech wrote:
--------------------------------------
Phil Allison:

Lamont Cranston wrote:

-------------------------------------
Oh, I hadn\'t thought about that. I thought it came with some ham radio junque and just assumed it was 60 hertz.
Now I wonder what its original use was? Also why I can\'t find data on the diode.


** FYI:

Only one diode has EDI 7712 on it - the other 7 are all labelled EDI 7711.
It\'s a DATE code, 11th or 12th week of 1977 !!.

The maker of the RHC8-5 is \"American Microsemiconductor\".
See vid: https://www.youtube.com/watch?v=JnpprGFAmpQ


Maybe EDI stands for this company:
http://www.e-edi.com/index.php

** OK - EDI make or supply the same number diode with their initials on it.


They have a RHC25-8
http://www.e-edi.com/pdf/HiVoltage/LHC_RHC.PDF


** Going on that example, the OP\'s diode is a fast, 5mA, 8kV type.
All fits with the idea it supplies only a tiny (uA) current from a 60Hz supply.

An electrostatic tweeter, from the late \'70s, is still a likely use for the multiplier.
The molded ABS mounting plate is big clue too.

.... Phil

I hadn\'t seen you post for a while. For some reason I hope you\'re doing
ok. The group would not be the same without you. (That\'s probably about
as close you\'ll get to a compliment from me.)

 

[Lamont Cranston]

On Tuesday, May 2, 2023 at 6:01:17 AM UTC-5, Chris Jones wrote:

On 2/05/2023 6:04 pm, Phil Allison wrote:
Matthias Czech wrote:

Oh very good, thanks all, for the diode info.
So, I have 60Hz HV transformers 8000V, If I use two diodes in series to build a half wave rectifier,
should I put equalizing resistors across the diodes. What value?
The largest value HV resistor I have is 2.5MΩ, is that to small?

Next, I want to limit the current to say 3ma, the transformers themselves are impedance limited to 15ma
when short circuited, but I want to protect the diodes from over current. How would I accomplish that?

Phil, it is good to hear from you, hope all is well.
The speaker idea for the multiplier is interesting. I have had the multiplier
board in the junque stash for so long, I don\'t know where I got it.

Thanks all, Mike

 

[John Larkin]

On Tue, 2 May 2023 06:02:12 -0700 (PDT), Lamont Cranston
<amdx62@gmail.com> wrote:

On Tuesday, May 2, 2023 at 6:01:17?AM UTC-5, Chris Jones wrote:
On 2/05/2023 6:04 pm, Phil Allison wrote:
Matthias Czech wrote:

Oh very good, thanks all, for the diode info.
So, I have 60Hz HV transformers 8000V, If I use two diodes in series to build a half wave rectifier,
should I put equalizing resistors across the diodes.

No. The HV diodes are already a lot of junctions in series.

A long time ago, diodes in series could fail because they had a
negative-resistance breakdown mode, so people put a lot of equalizing
passives. Modern diodes avalanche nicely.



What value?

The largest value HV resistor I have is 2.5M?, is that to small?

Next, I want to limit the current to say 3ma, the transformers themselves are impedance limited to 15ma
when short circuited, but I want to protect the diodes from over current. How would I accomplish that?

Use the two diodes as a half-wave doubler and let the cap impedance
limit current.

What do you want the HV for?

 

[legg]

On Mon, 1 May 2023 18:55:11 -0700 (PDT), Lamont Cranston
<amdx62@gmail.com> wrote:

In my junque box I have a High Voltage, Voltage multiplier.
I pulled it out to help my son on a project and it doesn\'t work as I expected.
Testing of the parts tells me they are all good. But the voltages don\'t seem right. I\'m using a Bryman 235 DVM with a 10M? input impedance. So, I\'m don\'t expect I\'m loading the circuit.
I took a picture and put voltage reads on the picture with some info about the diodes and caps. The diodes are about 1\" long and have a 10v drop at 2ma.
I would like to know the voltage ratings of the diodes and caps, but don\'t
find any info on the net.
Any Idea, why my voltages are way off?
Mikek

https://www.dropbox.com/s/ox8xomn4aiutprf/HV%20Multiplier.jpg?dl=0

If multiplication is ok in the first stage, at the frequency
present, then subsequent stages should also work. The first
stage passes the most current.

Check AC present on each stage - if it disappears, check for
a short.

Keep in mind that a uA of load will cause a volt of droop in
an 8nF cap at 60Hz - 1mA would cause 1KV of droop. So if this
does not have a static load, it will only supply very low current.

RL

 

[Lamont Cranston]

On Tuesday, May 2, 2023 at 9:10:42 AM UTC-5, John Larkin wrote:

Next, I want to limit the current to say 3ma, the transformers themselves are impedance limited to 15ma
when short circuited, but I want to protect the diodes from over current.. How would I accomplish that?
Use the two diodes as a half-wave doubler and let the cap impedance
limit current.

What do you want the HV for?

My son is doing some oil/water separation experiments at work, I don\'t really know what their vessel looks like or exactly
what they are doing, but it looks like fun.
I like the half-wave doubler idea to limit current.
Mikek

 

[John Larkin]

On Tue, 2 May 2023 07:38:23 -0700 (PDT), Lamont Cranston
<amdx62@gmail.com> wrote:

On Tuesday, May 2, 2023 at 9:10:42?AM UTC-5, John Larkin wrote:

Next, I want to limit the current to say 3ma, the transformers themselves are impedance limited to 15ma
when short circuited, but I want to protect the diodes from over current. How would I accomplish that?
Use the two diodes as a half-wave doubler and let the cap impedance
limit current.

What do you want the HV for?

My son is doing some oil/water separation experiments at work, I don\'t really know what their vessel looks like or exactly
what they are doing, but it looks like fun.
I like the half-wave doubler idea to limit current.
Mikek

He probably doesn\'t need much current.

Paper electrophoresis (sp?) is another fun thing that kids can do with
high voltage. I still can\'t believe that it works, but it does.

I built a Kerr Cell as a high school experiment, using AC from a neon
sign transformer. I used nitrobenzene, which turns out to be dangerous
to deadly on skin contact, not to mention flammible. In a couple of
Nero Wolfe mysteries, it was the murder weapon.

https://en.wikipedia.org/wiki/Nitrobenzene#Safety

Back when, any kid could go to a chemical supply house and buy
anything, deadly poisons or obvious explosive ingredients. And we got
used neon sign transformers free too.

 

[Lamont Cranston]

On Tuesday, May 2, 2023 at 9:52:35 AM UTC-5, John Larkin wrote:

On Tue, 2 May 2023 07:38:23 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:
On Tuesday, May 2, 2023 at 9:10:42?AM UTC-5, John Larkin wrote:

Next, I want to limit the current to say 3ma, the transformers themselves are impedance limited to 15ma
when short circuited, but I want to protect the diodes from over current. How would I accomplish that?
Use the two diodes as a half-wave doubler and let the cap impedance
limit current.

What do you want the HV for?

My son is doing some oil/water separation experiments at work, I don\'t really know what their vessel looks like or exactly
what they are doing, but it looks like fun.
I like the half-wave doubler idea to limit current.
Mikek
He probably doesn\'t need much current.

We think that\'s correct.

Paper electrophoresis (sp?) is another fun thing that kids can do with
high voltage. I still can\'t believe that it works, but it does.

And we got used neon sign transformers free too.

Yep, I got 6 or 7 when my bosses father cleaned out a build that previously held a neon sign company
about 30 years ago.
A few had an open on one side of the center tap.

So, experimenting, I put in 4Vac and get out 644Vdc of the doubler, that is a 160 to 1 ratio after the doubler.
The transformer is about a 75 to 1 ratio. After peak voltage and a little load, seems right.
Can I just measure the primary current and divide by 160 to get an idea of the DC output current?
As it stands 20Vac in to the transformer gives me a nice arc, and 320ma of AC on the primary.
If I can divide as I suggested, that is more current than I want thru the diodes, and I still have
a 5 times multiple to get to 120Vac in and near 19kV out.
i.e, I think I need more limiting.
Mikek

 

[Fred Bloggs]

On Monday, May 1, 2023 at 9:55:15 PM UTC-4, Lamont Cranston wrote:

In my junque box I have a High Voltage, Voltage multiplier.
I pulled it out to help my son on a project and it doesn\'t work as I expected.
Testing of the parts tells me they are all good. But the voltages don\'t seem right. I\'m using a Bryman 235 DVM with a 10MΩ input impedance. So, I\'m don\'t expect I\'m loading the circuit.
I took a picture and put voltage reads on the picture with some info about the diodes and caps. The diodes are about 1\" long and have a 10v drop at 2ma.
I would like to know the voltage ratings of the diodes and caps, but don\'t
find any info on the net.
Any Idea, why my voltages are way off?
Mikek

https://www.dropbox.com/s/ox8xomn4aiutprf/HV%20Multiplier.jpg?dl=0

Bottom row second capacitor from the left is not holding its charge OR the fourth diode from left is not conducting OR you have a cold solder joint in that area.

 

[Fred Bloggs]

On Monday, May 1, 2023 at 11:03:45 PM UTC-4, John Larkin wrote:

On Mon, 1 May 2023 18:55:11 -0700 (PDT), Lamont Cranston
amd...@gmail.com> wrote:

In my junque box I have a High Voltage, Voltage multiplier.
I pulled it out to help my son on a project and it doesn\'t work as I expected.
Testing of the parts tells me they are all good. But the voltages don\'t seem right. I\'m using a Bryman 235 DVM with a 10M? input impedance. So, I\'m don\'t expect I\'m loading the circuit.
I took a picture and put voltage reads on the picture with some info about the diodes and caps. The diodes are about 1\" long and have a 10v drop at 2ma.
I would like to know the voltage ratings of the diodes and caps, but don\'t
find any info on the net.
Any Idea, why my voltages are way off?
Mikek

https://www.dropbox.com/s/ox8xomn4aiutprf/HV%20Multiplier.jpg?dl=0
What frequency is your AC source?

It would be easy to measure the caps. Then teach the kid about Spice.

Easiest way to debug is to clip his voltage source ( reduced to something reasonable like 100V ) into the ladder. He clips reference lead to say middle bottom terminal, and the hot lead to lead of capacitor directly above it top row, then unsolder the one diode bridging the leads. That should multiply the voltage going in both directions, to right and left. That should narrow it down pretty fast. I think that\'s right anyway.

 

[Lamont Cranston]

I\'m down one cap after experimenting. As I stated before the Dissipation of that cap went from 0.003 up to 0.320 and the Capacitance didn\'t change.
Over night the capacitance did drop by about 10% and the dissipation dropped to 0.009. That\'s still 3 times the D of all the other caps. I\'m calling it bad.
So now I\'m using it as a quadrupler, excess parts removed from circuit.
With 150Vac input, I measured Voltage with 10MΩ meter at the output at 184Vdc, I have series connected Nine, 10MΩ resistors to make a 10 to 1 divider with my DVM. I now measure 684Vdc. Difference, 10MΩ load vs 100MΩ load. Using this data, I calculated a 43MΩ output impedance of the voltage quadrupler. I expect with no load it has an output of about 958V volts with 150Vac input.
As John said at the start, my frequency is too low or said another way,
my caps are to small.

Mikek

 

[Phil Allison]

Lamont Cranston wrote:
--------------------------------------

So now I\'m using it as a quadrupler, excess parts removed from circuit.
With 150Vac input, I measured Voltage with 10MΩ meter at the output at 184Vdc,
I have series connected Nine, 10MΩ resistors to make a 10 to 1 divider with my DVM.
I now measure 684Vdc. Difference, 10MΩ load vs 100MΩ load.
Using this data, I calculated a 43MΩ output impedance of the voltage quadrupler.
I expect with no load it has an output of about 958V volts with 150Vac input.

** This link might be useful to you:

https://www.extremeelectronics.co.uk/calculators/cw-voltage-calculator/


..... Phil