Low-noise isolated DC/DC...

[Piotr Wyderski]

Hi,

I need to provide power to a precision ADC over a 5+kV isolation
barrier. V_IN=10-16V, V_OUT=5V, I_OUT=60mA. Two more isolated 3.3V
voltages would be very welcome as well but are not strictly necessary.
In no case should the load exceed 0.5W.

Due to the wide input range, I need regulation, but I am not willing to
have any feedback components placed across the isolation barrier. The
load should be steady, so primary-side regulation looks attractive.

So far, I have come up with two options:

1. A PSR flyback based on the LT8301. A hands-down winner in terms of
circuit complexity. Cons: it is a flyback, so would produce a lot of noise.

2. A buck pre-regulator followed by a push-pull/full bridge. Pros:
almost 100% effective duty cycle would make the output filter a
no-brainer. Ultimately, there is the LT3439 with its ultra-low noise
properties. But I believe it would not be necessary, something cheaper
like the IR21531 with no output MOSFETs (the gate drivers driving the
primary directly) should suffice.

Low parts count and high reliability are at a premium. It is this weird
power level that allows for all sorts of tricks, so I would like to know
your suggestions.

Best regards, Piotr

 

[Jan Panteltje]

On a sunny day (Sun, 9 Aug 2020 09:00:46 +0200) it happened Piotr Wyderski
<peter.pan@neverland.mil> wrote in <rgo6ut$2p9ah$1@portraits.wsisiz.edu.pl>:

Hi,

I need to provide power to a precision ADC over a 5+kV isolation
barrier. V_IN=10-16V, V_OUT=5V, I_OUT=60mA. Two more isolated 3.3V
voltages would be very welcome as well but are not strictly necessary.
In no case should the load exceed 0.5W.

Due to the wide input range, I need regulation, but I am not willing to
have any feedback components placed across the isolation barrier. The
load should be steady, so primary-side regulation looks attractive.

So far, I have come up with two options:

1. A PSR flyback based on the LT8301. A hands-down winner in terms of
circuit complexity. Cons: it is a flyback, so would produce a lot of noise.

2. A buck pre-regulator followed by a push-pull/full bridge. Pros:
almost 100% effective duty cycle would make the output filter a
no-brainer. Ultimately, there is the LT3439 with its ultra-low noise
properties. But I believe it would not be necessary, something cheaper
like the IR21531 with no output MOSFETs (the gate drivers driving the
primary directly) should suffice.

Low parts count and high reliability are at a premium. It is this weird
power level that allows for all sorts of tricks, so I would like to know
your suggestions.

Best regards, Piotr

60W Edisonb lightbulb -> solar panel.
No noise.

Was discussed here years ago, laser diode into fiber or something..

 

[Piotr Wyderski]

Jan Panteltje wrote:

60W Edisonb lightbulb -> solar panel.
No noise.

This is not that silly, TLP190 is actually good at providing quietly
microamps of negative/floating bias currents.

Best regards, Piotr

 

[server]

On Sun, 09 Aug 2020 08:18:41 GMT, Jan Panteltje
<pNaOnStPeAlMtje@yahoo.com> wrote:

On a sunny day (Sun, 9 Aug 2020 09:00:46 +0200) it happened Piotr Wyderski
peter.pan@neverland.mil> wrote in <rgo6ut$2p9ah$1@portraits.wsisiz.edu.pl>:

Hi,

I need to provide power to a precision ADC over a 5+kV isolation
barrier. V_IN=10-16V, V_OUT=5V, I_OUT=60mA. Two more isolated 3.3V
voltages would be very welcome as well but are not strictly necessary.
In no case should the load exceed 0.5W.

Due to the wide input range, I need regulation, but I am not willing to
have any feedback components placed across the isolation barrier. The
load should be steady, so primary-side regulation looks attractive.

So far, I have come up with two options:

1. A PSR flyback based on the LT8301. A hands-down winner in terms of
circuit complexity. Cons: it is a flyback, so would produce a lot of noise.

2. A buck pre-regulator followed by a push-pull/full bridge. Pros:
almost 100% effective duty cycle would make the output filter a
no-brainer. Ultimately, there is the LT3439 with its ultra-low noise
properties. But I believe it would not be necessary, something cheaper
like the IR21531 with no output MOSFETs (the gate drivers driving the
primary directly) should suffice.

Low parts count and high reliability are at a premium. It is this weird
power level that allows for all sorts of tricks, so I would like to know
your suggestions.

Best regards, Piotr

60W Edisonb lightbulb -> solar panel.
No noise.

This is a bit so and so. With a standard sun (1000 W/m**2) about 0.5
dm**2 of solar power is required to provide 0.5 W of electricity. A 7
cm x 7 cm panel or 80 mm diameter cell is required.

The question is, can a 60 W incandescent bulb provide the same
illumination as the sun on that panel or cell area using concentrating
mirrors and lenses ?

The question is further complicated by different spectral distribution
of the sun, the solar panel and the incandescent lamp. The sun
contains a lot of short wave radiation, while majority of incandescent
lamp radiation is in the near IR. The panels quantum efficiency for IR
is low.

It might be a good idea to use an array of blue LEDs (as used in
\"white\" LEDs) and use a solar cell that can effectively use photons
with higher energy (shorter wavelengths).

>Was discussed here years ago, laser diode into fiber or something..

These were used e.g. for current transformer hanging on a 400 kV line.
The power demand was much lower to send down the measurements.

 

[Dmitriy Pshonkin]

https://datasheets.maximintegrated.com/en/ds/MAX13256.pdf

 

[Jan Panteltje]

On a sunny day (Sun, 09 Aug 2020 14:06:37 +0300) it happened
upsidedown@downunder.com wrote in
<htjvif1v27tg0qot49paos9244indc9nec@4ax.com>:

It might be a good idea to use an array of blue LEDs (as used in
\"white\" LEDs) and use a solar cell that can effectively use photons
with higher energy (shorter wavelengths).

Was discussed here years ago, laser diode into fiber or something..

These were used e.g. for current transformer hanging on a 400 kV line.
The power demand was much lower to send down the measurements.

Yes,
there is a lot online
up to 500 W to power drones:
https://powerlighttech.com/power-over-fiber-case-study-aerial-applications/

small to 250 mW:
http://www.mhgopower.com/laser_pof_Platform.html

small to 500 mW:
https://www.broadcom.com/products/fiber-optic-modules-components/industrial/optical-power-components/optical-power-and-data-link/afbr-pdpek521

google results after 3 minutes search.

found from
https://www.rp-photonics.com/bg/buy_power_over_fiber_systems.html?s=vbox

 

[Dmitriy Pshonkin]

http://ixbt.photo/?id=photo:1315772
The half-bridge operates at 500 kHz with a dead time of 200 ns.
The voltage at its output is trapezoidal.
The transistors are switched in ZVS mode with an additional 33-47 μH inductance and 1800 pF capacitance in parallel with the switches.
Galvanic isolation is carried out by two transformers connected by a wire in high voltage insulation.
Information is exchanged through the IRDA interface.

 

[Chris Jones]

On 09/08/2020 21:06, upsidedown@downunder.com wrote:

On Sun, 09 Aug 2020 08:18:41 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

On a sunny day (Sun, 9 Aug 2020 09:00:46 +0200) it happened Piotr Wyderski
peter.pan@neverland.mil> wrote in <rgo6ut$2p9ah$1@portraits.wsisiz.edu.pl>:

Hi,

I need to provide power to a precision ADC over a 5+kV isolation
barrier. V_IN=10-16V, V_OUT=5V, I_OUT=60mA. Two more isolated 3.3V
voltages would be very welcome as well but are not strictly necessary.
In no case should the load exceed 0.5W.

Due to the wide input range, I need regulation, but I am not willing to
have any feedback components placed across the isolation barrier. The
load should be steady, so primary-side regulation looks attractive.

So far, I have come up with two options:

1. A PSR flyback based on the LT8301. A hands-down winner in terms of
circuit complexity. Cons: it is a flyback, so would produce a lot of noise.

2. A buck pre-regulator followed by a push-pull/full bridge. Pros:
almost 100% effective duty cycle would make the output filter a
no-brainer. Ultimately, there is the LT3439 with its ultra-low noise
properties. But I believe it would not be necessary, something cheaper
like the IR21531 with no output MOSFETs (the gate drivers driving the
primary directly) should suffice.

Low parts count and high reliability are at a premium. It is this weird
power level that allows for all sorts of tricks, so I would like to know
your suggestions.

Best regards, Piotr

60W Edisonb lightbulb -> solar panel.
No noise.

This is a bit so and so. With a standard sun (1000 W/m**2) about 0.5
dm**2 of solar power is required to provide 0.5 W of electricity. A 7
cm x 7 cm panel or 80 mm diameter cell is required.

The question is, can a 60 W incandescent bulb provide the same
illumination as the sun on that panel or cell area using concentrating
mirrors and lenses ?
Yes, it can.

The question is further complicated by different spectral distribution
of the sun, the solar panel and the incandescent lamp. The sun
contains a lot of short wave radiation, while majority of incandescent
lamp radiation is in the near IR. The panels quantum efficiency for IR
is low.

No, it is fine for those IR wavelengths for which the photons have more
energy than the bandgap of silicon.

It might be a good idea to use an array of blue LEDs (as used in
\"white\" LEDs) and use a solar cell that can effectively use photons
with higher energy (shorter wavelengths).

Blue LEDs are not optimal. IR LEDs (~ 940nm or 880nm) are perfect. If
the photons had any more energy than that, it would just be wasted in
heating the solar cell, and creating higher-energy photons would require
more voltage to drive the LEDs.

It may be desirable to run the solar cell at more than 1 sun intensity.

Something I have not tried, but which might be useful is to modulate the
LED current with AC, and then connect the solar cell to the primary of a
step-up transformer, so that only one solar cell is required rather than
a series string of solar cells to generate the required output voltage.
With a series string of solar cells, the current will be determined by
the least illuminated cell, leading to a requirement for the solar cells
to be uniformly illuminated, which might be inconvenient. Having only
one solar cell removes this requirement, and may also result in a more
compact physical arrangement. A variation would be to use two solar
cells electrically connected in anti-parallel, connected to the
transformer primary, and illuminate them alternately by using separate
LEDs aimed at each one. This would provide push-pull or bipolar drive to
the transformer.

 

[server]

On Sun, 9 Aug 2020 09:00:46 +0200, Piotr Wyderski
<peter.pan@neverland.mil> wrote:

Hi,

I need to provide power to a precision ADC over a 5+kV isolation
barrier. V_IN=10-16V, V_OUT=5V, I_OUT=60mA. Two more isolated 3.3V
voltages would be very welcome as well but are not strictly necessary.
In no case should the load exceed 0.5W.

Due to the wide input range, I need regulation, but I am not willing to
have any feedback components placed across the isolation barrier. The
load should be steady, so primary-side regulation looks attractive.

So far, I have come up with two options:

1. A PSR flyback based on the LT8301. A hands-down winner in terms of
circuit complexity. Cons: it is a flyback, so would produce a lot of noise.

2. A buck pre-regulator followed by a push-pull/full bridge. Pros:
almost 100% effective duty cycle would make the output filter a
no-brainer. Ultimately, there is the LT3439 with its ultra-low noise
properties. But I believe it would not be necessary, something cheaper
like the IR21531 with no output MOSFETs (the gate drivers driving the
primary directly) should suffice.

Low parts count and high reliability are at a premium. It is this weird
power level that allows for all sorts of tricks, so I would like to know
your suggestions.

Best regards, Piotr

I\'ve been thinking about the same issue. I might need to design a very
small, fast UV-photodiode-amp-ADC board that runs off +12. I\'ll need
clean pos and neg analog supplies, and power for an ADC and a small
FPGA, all in a few cubic inches. Any hard switching supply will spray
spikes everywhere. I was doodling a sinewave-based converter or
something. Or maybe use a switcher chip but add a passive lowpass
filter before the transformer.

It might be easier to use a small commercial dc/dc brick and
shield/filter it hard.

An older design just switches the power converters off some
microseconds before the light pulse. I guess that\'s not a bad idea.



--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

 

[server]

On Sun, 9 Aug 2020 11:26:58 +0200, Piotr Wyderski
<peter.pan@neverland.mil> wrote:

Jan Panteltje wrote:

60W Edisonb lightbulb -> solar panel.
No noise.

This is not that silly, TLP190 is actually good at providing quietly
microamps of negative/floating bias currents.

Best regards, Piotr

PV isolators are great, for biasing up floating cascodes and such.
Pity the power levels are so low.



--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

 

[whit3rd]

On Sunday, August 9, 2020 at 4:06:42 AM UTC-7, upsid...@downunder.com wrote:

On Sun, 09 Aug 2020 08:18:41 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

On a sunny day (Sun, 9 Aug 2020 09:00:46 +0200) it happened Piotr Wyderski
peter.pan@neverland.mil> wrote in <rgo6ut$2p9ah$1@portraits.wsisiz.edu.pl>:

Hi,

I need to provide power to a precision ADC over a 5+kV isolation
barrier. V_IN=10-16V, V_OUT=5V, I_OUT=60mA.

60W Edisonb lightbulb -> solar panel.
No noise.

This is a bit so and so. With a standard sun (1000 W/m**2) about 0.5
dm**2 of solar power is required to provide 0.5 W of electricity. A 7
cm x 7 cm panel or 80 mm diameter cell is required.

The question is, can a 60 W incandescent bulb provide the same
illumination as the sun on that panel or cell area using concentrating
mirrors and lenses ?

The question is further complicated by different spectral distribution
of the sun, the solar panel and the incandescent lamp. The sun
contains a lot of short wave radiation, while majority of incandescent
lamp radiation is in the near IR. The panels quantum efficiency for IR
is low.

That\'s not right; the typical silicon solar cell peak efficiency is in near IR

<https://www.pveducation.org/sites/default/files/PVCDROM/Solar-Cell-Operation/Images/SRREAL.gif>

and it\'s not \'quantum efficiency\' that is the best metric here.

If you want an efficient system, you\'d be looking at IR LEDs, or something other
than mass-produced silicon solar cells.

The possibilities are many; one interesting approach was a ceramic rod, with an ultrasound
excitation at one end, and pickup at the other. It amounts to two speakers, an
exponential cone match/coupling, and a stick.

You can also spin the stick (motor-generator) and the belt-drive variant is good
for megavolts of isolation in van de Graaff installations.

A less interesting, but viable, approach is to turn the voltage off and install fresh batteries...

 

[bitrex]

On 8/9/2020 3:00 AM, Piotr Wyderski wrote:

Hi,

I need to provide power to a precision ADC over a 5+kV isolation
barrier. V_IN=10-16V, V_OUT=5V, I_OUT=60mA. Two more isolated 3.3V
voltages would be very welcome as well but are not strictly necessary.
In no case should the load exceed 0.5W.

Due to the wide input range, I need regulation, but I am not willing to
have any feedback components placed across the isolation barrier. The
load should be steady, so primary-side regulation looks attractive.

So far, I have come up with two options:

1. A PSR flyback based on the LT8301. A hands-down winner in terms of
circuit complexity. Cons: it is a flyback, so would produce a lot of noise.

2. A buck pre-regulator followed by a push-pull/full bridge. Pros:
almost 100% effective duty cycle would make the output filter a
no-brainer. Ultimately, there is the LT3439 with its ultra-low noise
properties. But I believe it would not be necessary, something cheaper
like the IR21531 with no output MOSFETs (the gate drivers driving the
primary directly) should suffice.

Low parts count and high reliability are at a premium. It is this weird
power level that allows for all sorts of tricks, so I would like to know
your suggestions.

    Best regards, Piotr

These Silicon Labs isolated gate drivers are excellent parts, wicked
fast and up to 5kV isolation. you could prolly drive a small forward
converter directly from one of the 3 amp duals.

<https://www.silabs.com/isolation/isolated-gate-drivers>

If one can live with the lower secondary supply rating by comparison
they\'re as good or better than the equivalent from AD, and for about
half as much $$$.

 

[bitrex]

On 8/9/2020 10:47 AM, jlarkin@highlandsniptechnology.com wrote:

On Sun, 9 Aug 2020 09:00:46 +0200, Piotr Wyderski
peter.pan@neverland.mil> wrote:

Hi,

I need to provide power to a precision ADC over a 5+kV isolation
barrier. V_IN=10-16V, V_OUT=5V, I_OUT=60mA. Two more isolated 3.3V
voltages would be very welcome as well but are not strictly necessary.
In no case should the load exceed 0.5W.

Due to the wide input range, I need regulation, but I am not willing to
have any feedback components placed across the isolation barrier. The
load should be steady, so primary-side regulation looks attractive.

So far, I have come up with two options:

1. A PSR flyback based on the LT8301. A hands-down winner in terms of
circuit complexity. Cons: it is a flyback, so would produce a lot of noise.

2. A buck pre-regulator followed by a push-pull/full bridge. Pros:
almost 100% effective duty cycle would make the output filter a
no-brainer. Ultimately, there is the LT3439 with its ultra-low noise
properties. But I believe it would not be necessary, something cheaper
like the IR21531 with no output MOSFETs (the gate drivers driving the
primary directly) should suffice.

Low parts count and high reliability are at a premium. It is this weird
power level that allows for all sorts of tricks, so I would like to know
your suggestions.

Best regards, Piotr

I\'ve been thinking about the same issue. I might need to design a very
small, fast UV-photodiode-amp-ADC board that runs off +12. I\'ll need
clean pos and neg analog supplies, and power for an ADC and a small
FPGA, all in a few cubic inches. Any hard switching supply will spray
spikes everywhere. I was doodling a sinewave-based converter or
something. Or maybe use a switcher chip but add a passive lowpass
filter before the transformer.

It might be easier to use a small commercial dc/dc brick and
shield/filter it hard.

An older design just switches the power converters off some
microseconds before the light pulse. I guess that\'s not a bad idea.

Luv these things:

<https://www.mouser.com/ProductDetail/Silicon-Labs/SI8751AB-IS?qs=j6MGy4L9yX3n3y96xP00SQ%3D%3D?

Into an appropriate 2-pole LC low-pass on the secondary a dual will spit
out sine waves across an isolation barrier up to 10 MHz or so not a
problem. A coupled inductor/choke and driving differentially keeps the
filter compact.

 

[bitrex]

On 8/9/2020 3:00 AM, Piotr Wyderski wrote:

Hi,

I need to provide power to a precision ADC over a 5+kV isolation
barrier. V_IN=10-16V, V_OUT=5V, I_OUT=60mA. Two more isolated 3.3V
voltages would be very welcome as well but are not strictly necessary.
In no case should the load exceed 0.5W.

Due to the wide input range, I need regulation, but I am not willing to
have any feedback components placed across the isolation barrier. The
load should be steady, so primary-side regulation looks attractive.

If the load is constant an isolated Cuk converter could be an option.

The input current and output current are continuous in the ideal Cuk, so
if the secondary load is constant the impedance looking into the primary
is always well-defined so primary-side regulation should be easier.

So far, I have come up with two options:

1. A PSR flyback based on the LT8301. A hands-down winner in terms of
circuit complexity. Cons: it is a flyback, so would produce a lot of noise.

2. A buck pre-regulator followed by a push-pull/full bridge. Pros:
almost 100% effective duty cycle would make the output filter a
no-brainer. Ultimately, there is the LT3439 with its ultra-low noise
properties. But I believe it would not be necessary, something cheaper
like the IR21531 with no output MOSFETs (the gate drivers driving the
primary directly) should suffice.

Low parts count and high reliability are at a premium. It is this weird
power level that allows for all sorts of tricks, so I would like to know
your suggestions.

    Best regards, Piotr

 

[bitrex]

On 8/9/2020 2:59 PM, bitrex wrote:

On 8/9/2020 3:00 AM, Piotr Wyderski wrote:
Hi,

I need to provide power to a precision ADC over a 5+kV isolation
barrier. V_IN=10-16V, V_OUT=5V, I_OUT=60mA. Two more isolated 3.3V
voltages would be very welcome as well but are not strictly necessary.
In no case should the load exceed 0.5W.

Due to the wide input range, I need regulation, but I am not willing
to have any feedback components placed across the isolation barrier.
The load should be steady, so primary-side regulation looks attractive.

If the load is constant an isolated Cuk converter could be an option.

The input current and output current are continuous in the ideal Cuk, so
if the secondary load is constant the impedance looking into the primary
is always well-defined so primary-side regulation should be easier.

Into the primary-side of the converter from the perspective of the
primary-side supply, rather

 

[bitrex]

On 8/9/2020 1:55 PM, whit3rd wrote:

On Sunday, August 9, 2020 at 4:06:42 AM UTC-7, upsid...@downunder.com wrote:
On Sun, 09 Aug 2020 08:18:41 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

On a sunny day (Sun, 9 Aug 2020 09:00:46 +0200) it happened Piotr Wyderski
peter.pan@neverland.mil> wrote in <rgo6ut$2p9ah$1@portraits.wsisiz.edu.pl>:

Hi,

I need to provide power to a precision ADC over a 5+kV isolation
barrier. V_IN=10-16V, V_OUT=5V, I_OUT=60mA.

60W Edisonb lightbulb -> solar panel.
No noise.

This is a bit so and so. With a standard sun (1000 W/m**2) about 0.5
dm**2 of solar power is required to provide 0.5 W of electricity. A 7
cm x 7 cm panel or 80 mm diameter cell is required.

The question is, can a 60 W incandescent bulb provide the same
illumination as the sun on that panel or cell area using concentrating
mirrors and lenses ?

The question is further complicated by different spectral distribution
of the sun, the solar panel and the incandescent lamp. The sun
contains a lot of short wave radiation, while majority of incandescent
lamp radiation is in the near IR. The panels quantum efficiency for IR
is low.

That\'s not right; the typical silicon solar cell peak efficiency is in near IR

https://www.pveducation.org/sites/default/files/PVCDROM/Solar-Cell-Operation/Images/SRREAL.gif

and it\'s not \'quantum efficiency\' that is the best metric here.

If you want an efficient system, you\'d be looking at IR LEDs, or something other
than mass-produced silicon solar cells.

The possibilities are many; one interesting approach was a ceramic rod, with an ultrasound
excitation at one end, and pickup at the other. It amounts to two speakers, an
exponential cone match/coupling, and a stick.

You can also spin the stick (motor-generator) and the belt-drive variant is good
for megavolts of isolation in van de Graaff installations.

A less interesting, but viable, approach is to turn the voltage off and install fresh batteries...

Unless one actually needs just microamperes of current these schemes are
an engineering rathole IMO. They never end up being cost-effective from
a size, cost, or design-time point of view.

Sometimes it doesn\'t pay to be clever, just use a magnetic/transformer
converter and get paid! Don\'t look for clever hills to die on cuz you\'re
gonna die there

 

[bitrex]

On 8/9/2020 3:10 PM, bitrex wrote:

On 8/9/2020 1:55 PM, whit3rd wrote:
On Sunday, August 9, 2020 at 4:06:42 AM UTC-7, upsid...@downunder.com
wrote:
On Sun, 09 Aug 2020 08:18:41 GMT, Jan Panteltje
pNaOnStPeAlMtje@yahoo.com> wrote:

On a sunny day (Sun, 9 Aug 2020 09:00:46 +0200) it happened Piotr
Wyderski
peter.pan@neverland.mil> wrote in
rgo6ut$2p9ah$1@portraits.wsisiz.edu.pl>:

Hi,

I need to provide power to a precision ADC over a 5+kV isolation
barrier. V_IN=10-16V, V_OUT=5V, I_OUT=60mA.

60W Edisonb lightbulb -> solar panel.
No noise.

This is a bit so and so. With a standard sun (1000 W/m**2) about 0.5
dm**2 of solar power is required to provide 0.5 W of electricity. A 7
cm x 7 cm panel or 80 mm diameter cell is required.

The question is, can a 60 W incandescent bulb provide the same
illumination as the sun on that panel or cell area using concentrating
mirrors and lenses ?

The question is further complicated by different spectral distribution
of the sun, the solar panel and the incandescent lamp. The sun
contains a lot of short wave radiation, while majority of incandescent
lamp radiation is in the near IR. The panels quantum efficiency for IR
is low.

That\'s not right; the typical silicon solar cell peak efficiency is in
near IR

https://www.pveducation.org/sites/default/files/PVCDROM/Solar-Cell-Operation/Images/SRREAL.gif


and it\'s not \'quantum efficiency\' that is the best metric here.

If you want an efficient system, you\'d be looking at IR LEDs, or
something other
than mass-produced silicon solar cells.

The possibilities are many; one interesting approach was a ceramic
rod, with an ultrasound
excitation at one end, and pickup at the other.   It amounts to two
speakers, an
exponential cone match/coupling, and a stick.

You can also spin the stick (motor-generator) and the belt-drive
variant is good
for megavolts of isolation in van de Graaff installations.

A less interesting, but viable, approach is to turn the voltage off
and install fresh batteries...


Unless one actually needs just microamperes of current these schemes are
an engineering rathole IMO. They never end up being cost-effective from
a size, cost, or design-time point of view.

Er, use \"investment-effective\" as a term there, perhaps, to avoid being
redundant

 

[bitrex]

On 8/9/2020 10:53 AM, jlarkin@highlandsniptechnology.com wrote:

On Sun, 9 Aug 2020 11:26:58 +0200, Piotr Wyderski
peter.pan@neverland.mil> wrote:

Jan Panteltje wrote:

60W Edisonb lightbulb -> solar panel.
No noise.

This is not that silly, TLP190 is actually good at providing quietly
microamps of negative/floating bias currents.

Best regards, Piotr

PV isolators are great, for biasing up floating cascodes and such.
Pity the power levels are so low.

A dummy says \"Hmm, magnetic converter seems too complex here, I\'m going
to try photovoltaic.\"

ERRRFFF

Unless microamps is actually all you need.

 

[server]

On Sun, 9 Aug 2020 15:16:51 -0400, bitrex <user@example.net> wrote:

On 8/9/2020 10:53 AM, jlarkin@highlandsniptechnology.com wrote:
On Sun, 9 Aug 2020 11:26:58 +0200, Piotr Wyderski
peter.pan@neverland.mil> wrote:

Jan Panteltje wrote:

60W Edisonb lightbulb -> solar panel.
No noise.

This is not that silly, TLP190 is actually good at providing quietly
microamps of negative/floating bias currents.

Best regards, Piotr

PV isolators are great, for biasing up floating cascodes and such.
Pity the power levels are so low.





A dummy says \"Hmm, magnetic converter seems too complex here, I\'m going
to try photovoltaic.\"

ERRRFFF

Unless microamps is actually all you need.

Sometimes, yes.

https://www.dropbox.com/s/rmcbw8c0bxcmm1l/T840_1400v_amp.jpg?raw=1

A PV makes the gate voltage for the upper cascode fet. Current
required is zero.

We had that PV around, from making our own SSRs.

PVs sure are small and cheap and quiet.




--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard

 

[bitrex]

On 8/9/2020 4:46 PM, jlarkin@highlandsniptechnology.com wrote:

On Sun, 9 Aug 2020 15:16:51 -0400, bitrex <user@example.net> wrote:

On 8/9/2020 10:53 AM, jlarkin@highlandsniptechnology.com wrote:
On Sun, 9 Aug 2020 11:26:58 +0200, Piotr Wyderski
peter.pan@neverland.mil> wrote:

Jan Panteltje wrote:

60W Edisonb lightbulb -> solar panel.
No noise.

This is not that silly, TLP190 is actually good at providing quietly
microamps of negative/floating bias currents.

Best regards, Piotr

PV isolators are great, for biasing up floating cascodes and such.
Pity the power levels are so low.





A dummy says \"Hmm, magnetic converter seems too complex here, I\'m going
to try photovoltaic.\"

ERRRFFF

Unless microamps is actually all you need.

Sometimes, yes.

https://www.dropbox.com/s/rmcbw8c0bxcmm1l/T840_1400v_amp.jpg?raw=1

A PV makes the gate voltage for the upper cascode fet. Current
required is zero.

We had that PV around, from making our own SSRs.

PVs sure are small and cheap and quiet.

A gate bias generator that runs off the waste heat produced by its own
power FETs would be amusing and aside from the startup problem doesn\'t
violate any laws of thermodynamics AFAIK

<https://www.analog.com/en/products/ltc3108.html>