Parasitic capacitance of SMD resistors and their generated noise...

  • Thread starter pavelm...@gmail.com
  • Start date
John S wrote:

jlarkin@highlandsniptechnology.com wrote:

Given 10 identical resistors in series, each drops 1/10 of the total
voltage.

Yes. But the resistance at rated voltage is much lower than it is at a
couple of volts.
Click to expand...

Weird... The current is the same. But as the voltage drops, the total
remaining resistance decreases too, moving through the divider. Should be
simple but... That\'s why we depend on rules.
 
On a sunny day (Tue, 8 Mar 2022 12:56:46 -0800 (PST)) it happened whit3rd
<whit3rd@gmail.com> wrote in
<9168331e-8253-4e0a-b06a-a31309a07da3n@googlegroups.com>:

To prevent corona around a carbon resistor, you might consider getting the
resistor sealed in vacuum (glass tube package). At 45 kV auto ignition
wiring just had to go to 8mm diameter silicone insulation: the corona in
silicone is harder to start than corona in air, so... you build up the
insulator to fill the high-field volume entirely.

Victoreen and Ohmite make vacuum packages : <https://www.ebay.com/itm/123046764521
Click to expand...

Very nice
This morning i ws tinking abiut different physics to measue g=high voltages
Icame upo (in my mind that is( with a varant f teh elctrometer

2 charged plates, on on ground the other on the HV,
and then the ground one mounted on a piezo like weight sensor
The attraction between the plates would perhaps be measurable, and no current load

--------- HV plate

---------- GND plate
///////// -> weight sensor
============= PCB (or whatever

Accuracy. probably bad


For my small PMT this setup works fine up to a kV or so:
http://panteltje.com/pub/PMT_HV_supply_componet_side_img_3180.jpg
HV resistor divider is on the far left.

http://panteltje.com/pub/PMT_HV_supply_with_regulator_img_3175.jpg

is stabilized of course:
http://www.panteltje.com/pub/PMT_regulated_power_supply_diagram_img_3182.jpg
filtered PWM rom a PIC micro controls it.
Been working fine for 11 years now. no idea how accurate, few volt perhaps.
use a precision opamp?

I have an other one for a bigger PMT with a lot more voltage:
http://panteltje.com/panteltje/pic/sc_pic/
also PIC controlled

1 ppm ..no but shoud be possible? 1kV 1mV sigh.. ripple.... ?
LOL

Do not move near it!
 
On Wed, 09 Mar 2022 07:45:27 GMT, Jan Panteltje
<pNaonStpealmtje@yahoo.com> wrote:

On a sunny day (Tue, 8 Mar 2022 12:56:46 -0800 (PST)) it happened whit3rd
whit3rd@gmail.com> wrote in
9168331e-8253-4e0a-b06a-a31309a07da3n@googlegroups.com>:

To prevent corona around a carbon resistor, you might consider getting the
resistor sealed in vacuum (glass tube package). At 45 kV auto ignition
wiring just had to go to 8mm diameter silicone insulation: the corona in
silicone is harder to start than corona in air, so... you build up the
insulator to fill the high-field volume entirely.

Victoreen and Ohmite make vacuum packages : <https://www.ebay.com/itm/123046764521

Very nice
This morning i ws tinking abiut different physics to measue g=high voltages
Icame upo (in my mind that is( with a varant f teh elctrometer

2 charged plates, on on ground the other on the HV,
and then the ground one mounted on a piezo like weight sensor
The attraction between the plates would perhaps be measurable, and no current load

--------- HV plate

---------- GND plate
///////// -> weight sensor
============= PCB (or whatever

Accuracy. probably bad


For my small PMT this setup works fine up to a kV or so:
http://panteltje.com/pub/PMT_HV_supply_componet_side_img_3180.jpg
HV resistor divider is on the far left.

http://panteltje.com/pub/PMT_HV_supply_with_regulator_img_3175.jpg

is stabilized of course:
http://www.panteltje.com/pub/PMT_regulated_power_supply_diagram_img_3182.jpg
filtered PWM rom a PIC micro controls it.
Been working fine for 11 years now. no idea how accurate, few volt perhaps.
use a precision opamp?

I have an other one for a bigger PMT with a lot more voltage:
http://panteltje.com/panteltje/pic/sc_pic/
also PIC controlled

1 ppm ..no but shoud be possible? 1kV 1mV sigh.. ripple.... ?
LOL
Click to expand...

It might get expensive.

Do not move near it!
Click to expand...

Nice stuff. MMBD5004S/1SS398TE85LF is a dual 400v diode in SOT23,
which can shorten a C-W multiplier string.

https://www.dropbox.com/s/jfx8it5acjwg4je/Z206_CWmult.JPG?raw=1

https://www.dropbox.com/s/2pgawxq6a0xnqxz/DRQ_11.asc?dl=0



--

I yam what I yam - Popeye
 
On Tuesday, March 8, 2022 at 11:45:48 PM UTC-8, Jan Panteltje wrote:

This morning i ws tinking abiut different physics to measue g=high voltages
Icame upo (in my mind that is( with a varant f teh elctrometer

2 charged plates, on on ground the other on the HV,
and then the ground one mounted on a piezo like weight sensor
The attraction between the plates would perhaps be measurable, and no current load

--------- HV plate

---------- GND plate
///////// -> weight sensor
============= PCB (or whatever

Accuracy. probably bad
Click to expand...

That\'s a variant of traditional electrostatic voltmeter design with a vane
and plates, which typically is done in rotary fashion with a hairspring for
return force... and requires jeweled bearings and level adjustment...
it\'s a fiddly nuisance of an instrument, but does pretty well at
sorting out kilovolts without many picoamps of leakage.
I suspect the weight sensor will respond to every bit of building shake
in the wind...


For my small PMT this setup works fine up to a kV or so:
http://panteltje.com/pub/PMT_HV_supply_componet_side_img_3180.jpg
Click to expand...

Yow. So many parts just to replace a single vacuum tube rectifier...

> HV resistor divider is on the far left.

And then the long string of low-V resistors...

It\'d almost be easier to meter with a field mill (motorized vane
changing capacitance-to-electrode, and AC amplification
of the resulting current). An interesting variant would be
to program a second electrode with some smart PWM
and balance the pulses from the known-voltage electrode
and the unknown-voltage electrode.
 
Jan Panteltje wrote:
On a sunny day (Tue, 8 Mar 2022 12:56:46 -0800 (PST)) it happened whit3rd
whit3rd@gmail.com> wrote in
9168331e-8253-4e0a-b06a-a31309a07da3n@googlegroups.com>:

To prevent corona around a carbon resistor, you might consider getting the
resistor sealed in vacuum (glass tube package). At 45 kV auto ignition
wiring just had to go to 8mm diameter silicone insulation: the corona in
silicone is harder to start than corona in air, so... you build up the
insulator to fill the high-field volume entirely.

Victoreen and Ohmite make vacuum packages : <https://www.ebay.com/itm/123046764521

Very nice
This morning i ws tinking abiut different physics to measue g=high voltages
Icame upo (in my mind that is( with a varant f teh elctrometer

2 charged plates, on on ground the other on the HV,
and then the ground one mounted on a piezo like weight sensor
The attraction between the plates would perhaps be measurable, and no current load

--------- HV plate

---------- GND plate
///////// -> weight sensor
============= PCB (or whatever

Accuracy. probably bad


For my small PMT this setup works fine up to a kV or so:
http://panteltje.com/pub/PMT_HV_supply_componet_side_img_3180.jpg
HV resistor divider is on the far left.

http://panteltje.com/pub/PMT_HV_supply_with_regulator_img_3175.jpg

is stabilized of course:
http://www.panteltje.com/pub/PMT_regulated_power_supply_diagram_img_3182.jpg
filtered PWM rom a PIC micro controls it.
Been working fine for 11 years now. no idea how accurate, few volt perhaps.
use a precision opamp?

I have an other one for a bigger PMT with a lot more voltage:
http://panteltje.com/panteltje/pic/sc_pic/
also PIC controlled

1 ppm ..no but shoud be possible? 1kV 1mV sigh.. ripple.... ?
LOL

Do not move near it!
Click to expand...

The classical method is the vibrating-reed electrometer.

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
 
On a sunny day (Wed, 9 Mar 2022 13:35:31 -0500) it happened Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote in
<dc533e1c-b0f1-5bca-1a91-f9e9d1fdaa5f@electrooptical.net>:

Jan Panteltje wrote:
On a sunny day (Tue, 8 Mar 2022 12:56:46 -0800 (PST)) it happened whit3rd
whit3rd@gmail.com> wrote in
9168331e-8253-4e0a-b06a-a31309a07da3n@googlegroups.com>:

To prevent corona around a carbon resistor, you might consider getting the
resistor sealed in vacuum (glass tube package). At 45 kV auto ignition
wiring just had to go to 8mm diameter silicone insulation: the corona in
silicone is harder to start than corona in air, so... you build up the
insulator to fill the high-field volume entirely.

Victoreen and Ohmite make vacuum packages : <https://www.ebay.com/itm/123046764521

Very nice
This morning i ws tinking abiut different physics to measue g=high voltages
Icame upo (in my mind that is( with a varant f teh elctrometer

2 charged plates, on on ground the other on the HV,
and then the ground one mounted on a piezo like weight sensor
The attraction between the plates would perhaps be measurable, and no current load

--------- HV plate

---------- GND plate
///////// -> weight sensor
============= PCB (or whatever

Accuracy. probably bad


For my small PMT this setup works fine up to a kV or so:
http://panteltje.com/pub/PMT_HV_supply_componet_side_img_3180.jpg
HV resistor divider is on the far left.

http://panteltje.com/pub/PMT_HV_supply_with_regulator_img_3175.jpg

is stabilized of course:
http://www.panteltje.com/pub/PMT_regulated_power_supply_diagram_img_3182.jpg
filtered PWM rom a PIC micro controls it.
Been working fine for 11 years now. no idea how accurate, few volt perhaps.
use a precision opamp?

I have an other one for a bigger PMT with a lot more voltage:
http://panteltje.com/panteltje/pic/sc_pic/
also PIC controlled

1 ppm ..no but shoud be possible? 1kV 1mV sigh.. ripple.... ?
LOL

Do not move near it!






The classical method is the vibrating-reed electrometer.
Click to expand...

Thanks, bit of googling found a nice wikipedia article:
https://en.wikipedia.org/wiki/Electrometer
 
On Wednesday, March 9, 2022 at 10:35:47 AM UTC-8, Phil Hobbs wrote:
Jan Panteltje wrote:

This morning i ws tinking abiut different physics to measue g=high voltages
Icame upo (in my mind that is( with a varant f teh elctrometer

2 charged plates, on on ground the other on the HV,
and then the ground one mounted on a piezo like weight sensor
The attraction between the plates would perhaps be measurable, and no current load

--------- HV plate

---------- GND plate
///////// -> weight sensor
============= PCB (or whatever

Accuracy. probably bad
Click to expand...

1 ppm ..no but shoud be possible? 1kV 1mV sigh.. ripple.... ?
LOL

Do not move near it!

The classical method is the vibrating-reed electrometer.
Click to expand...

That\'s also a \'do not move near it\' solution. I scavenged a head unit
from an old Cary 31 vibrating-reed electrometer, and it\'s got 10lbs of cast iron to
keep acoustic input to a minimum; there were selected tubes
inside to deal with the microphonic feedback, and anyone who
could afford it (circa 1970) was swapping in new sockets and nuvistor
tubes, \'cuz microphonics.
 
whit3rd wrote:
On Wednesday, March 9, 2022 at 10:35:47 AM UTC-8, Phil Hobbs wrote:
Jan Panteltje wrote:

This morning i ws tinking abiut different physics to measue g=high voltages
Icame upo (in my mind that is( with a varant f teh elctrometer

2 charged plates, on on ground the other on the HV,
and then the ground one mounted on a piezo like weight sensor
The attraction between the plates would perhaps be measurable, and no current load

--------- HV plate

---------- GND plate
///////// -> weight sensor
============= PCB (or whatever

Accuracy. probably bad


1 ppm ..no but shoud be possible? 1kV 1mV sigh.. ripple.... ?
LOL

Do not move near it!

The classical method is the vibrating-reed electrometer.

That\'s also a \'do not move near it\' solution. I scavenged a head unit
from an old Cary 31 vibrating-reed electrometer, and it\'s got 10lbs of cast iron to
keep acoustic input to a minimum; there were selected tubes
inside to deal with the microphonic feedback, and anyone who
could afford it (circa 1970) was swapping in new sockets and nuvistor
tubes, \'cuz microphonics.
Click to expand...

\"Doctor, doctor, it hurts when I go like this!\"

\"So don\'t go like that.\"

I used to have a handheld electrometer with an analog dial. It looked a
bit like an old CdS photographic light meter, and worked fine.

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
 
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