From Newsgroup: sci.electronics.design

My summer intern Enzo is designing a pulse generator and he doesn't
have much time before school starts, so I volunteered to do the power
supply for him.

This is an ordinary slope-compensated autotransformer-flyback Cockcroft-Walton-voltage-multiplier programmable high-voltage power
supply.


https://www.dropbox.com/scl/fi/lzzin9qphlfh51uznaio4/T820_HV_2.jpg?rlkey=6nw9snqxyual6o06oap8t490u&raw=1

https://www.dropbox.com/scl/fi/n7c3796ihw8dex289c3x0/T820_HV_2.asc?rlkey=7o1np3c5wys8sz8lkj8g4r42d&dl=0

I had a hard time getting the loop compensation right, but that turned
out to be mostly a dumb mistake and a mediocre data sheet. It sims
crazy slow so some of the oddities are hacks to speed it up.

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From Newsgroup: sci.electronics.design

john larkin <jl@glen--canyon.com> Wrote in message:r

My summer intern Enzo is designing a pulse generator and he doesn'thave much time before school starts, so I volunteered to do the powersupply for him.This is an ordinary slope-compensated autotransformer-flybackCockcroft-Walton-voltage-multiplier programmable high-voltage powersupply.https://www.dropbox.com/scl/fi/lzzin9qphlfh51uznaio4/T820_HV_2.jpg?rlkey=6nw9snqxyual6o06oap8t490u&raw=1https://www.dropbox.com/scl/fi/n7c3796ihw8dex289c3x0/T820_HV_2.asc?rlkey=7o1np3c5wys8sz8lkj8g4r42d&dl=0I had a hard time getting the loop compensation right, but that turnedout to be mostly a dumb mistake and a mediocre data sheet. It simscrazy slow so some of the oddities are hacks to speed it up.

https://www.edn.com/high-voltage-feed-forward/

Cheers
--


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From Newsgroup: sci.electronics.design

On Tue, 19 Aug 2025 10:27:26 -0400 (EDT), Martin Rid <martin_riddle@verison.net> wrote:

john larkin <jl@glen--canyon.com> Wrote in message:r

My summer intern Enzo is designing a pulse generator and he doesn'thave much time before school starts, so I volunteered to do the powersupply for him.This is an ordinary slope-compensated autotransformer-flybackCockcroft-Walton-voltage-multiplier programmable high-voltage powersupply.https://www.dropbox.com/scl/fi/lzzin9qphlfh51uznaio4/T820_HV_2.jpg?rlkey=6nw9snqxyual6o06oap8t490u&raw=1https://www.dropbox.com/scl/fi/n7c3796ihw8dex289c3x0/T820_HV_2.asc?rlkey=7o1np3c5wys8sz8lkj8g4r42d&dl=0I had a hard time getting the loop compensation right, but that turnedout to be mostly a dumb mistake and a mediocre data sheet. It simscrazy slow so some of the oddities are hacks to speed it up.

https://www.edn.com/high-voltage-feed-forward/

Cheers

Ignoring the hyperbolic text, I don't see a great advantage to that.
Here's my latest version:

https://www.dropbox.com/scl/fi/kn68w69oyggbrb1cf4fyv/T820_PS_4.jpg?rlkey=1upe3t5pgyulp373mae4wiskx&raw=1

It has nice dynamics and can't make more than 650 volts no matter
what's programmed; that protects the GaN fets it will drive.

Here's an isolated (transformer coupled) output pulse into 50 ohms:

https://www.dropbox.com/scl/fi/w05ji6rtj2cq1w6sva72p/IMG_7031.jpg?rlkey=58qloz9h8r8yxcpwblrl3mw6q&raw=1

It's little ratty, good enough, but we think we can pretty it up in a production version.

Those pulses are 8.5 KW but low energy and at 1 KHz, low power. But we
keep blowing out attenuators, even 20 watt ones.

Low rep rates help, but 100 Hz into a sampling scope is really
tedious.

My intern loves my old Tek 11802. He's amazed that it has a real
glass CRT *and* touch screen.

--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: sci.electronics.design

On 2025-08-19 11:45, john larkin wrote:

On Tue, 19 Aug 2025 10:27:26 -0400 (EDT), Martin Rid <martin_riddle@verison.net> wrote:

john larkin <jl@glen--canyon.com> Wrote in message:r

My summer intern Enzo is designing a pulse generator and he doesn'thave much time before school starts, so I volunteered to do the powersupply for him.This is an ordinary slope-compensated autotransformer-flybackCockcroft-Walton-voltage-multiplier programmable high-voltage powersupply.https://www.dropbox.com/scl/fi/lzzin9qphlfh51uznaio4/T820_HV_2.jpg?rlkey=6nw9snqxyual6o06oap8t490u&raw=1https://www.dropbox.com/scl/fi/n7c3796ihw8dex289c3x0/T820_HV_2.asc?rlkey=7o1np3c5wys8sz8lkj8g4r42d&dl=0I had a hard time getting the loop compensation right, but that turnedout to be mostly a dumb mistake and a mediocre data sheet. It simscrazy slow so some of the oddities are hacks to speed it up.

https://www.edn.com/high-voltage-feed-forward/

Cheers

Ignoring the hyperbolic text, I don't see a great advantage to that.
Here's my latest version:

https://www.dropbox.com/scl/fi/kn68w69oyggbrb1cf4fyv/T820_PS_4.jpg?rlkey=1upe3t5pgyulp373mae4wiskx&raw=1

It has nice dynamics and can't make more than 650 volts no matter
what's programmed; that protects the GaN fets it will drive.

Here's an isolated (transformer coupled) output pulse into 50 ohms:

https://www.dropbox.com/scl/fi/w05ji6rtj2cq1w6sva72p/IMG_7031.jpg?rlkey=58qloz9h8r8yxcpwblrl3mw6q&raw=1

It's little ratty, good enough, but we think we can pretty it up in a production version.

Those pulses are 8.5 KW but low energy and at 1 KHz, low power. But we
keep blowing out attenuators, even 20 watt ones.

Could be internal arcing in the cermet. That'll have a lower energy
threshold than thermal.

Low rep rates help, but 100 Hz into a sampling scope is really
tedious.

Yup. Back in my antenna-coupled tunnel junction days, I was using a
20-Hz pulsed laser with lousy pulse-to-pulse energy stability, so it
took the best part of an hour to get one trace (512 points) with 100
averages.

My intern loves my old Tek 11802. He's amazed that it has a real
glass CRT *and* touch screen.

I love mine too. Have you noticed SD-24s dying lately? I have three
out of four showing "Illegal channel number".

Fortunately I have these little 60-ps TDR modules that we've made, but
they aren't as flexible as SD-24s.

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

--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: sci.electronics.design

On Wed, 20 Aug 2025 16:52:05 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2025-08-19 11:45, john larkin wrote:

On Tue, 19 Aug 2025 10:27:26 -0400 (EDT), Martin Rid
<martin_riddle@verison.net> wrote:

john larkin <jl@glen--canyon.com> Wrote in message:r

My summer intern Enzo is designing a pulse generator and he doesn'thave much time before school starts, so I volunteered to do the powersupply for him.This is an ordinary slope-compensated autotransformer-flybackCockcroft-Walton-voltage-multiplier programmable high-voltage powersupply.https://www.dropbox.com/scl/fi/lzzin9qphlfh51uznaio4/T820_HV_2.jpg?rlkey=6nw9snqxyual6o06oap8t490u&raw=1https://www.dropbox.com/scl/fi/n7c3796ihw8dex289c3x0/T820_HV_2.asc?rlkey=7o1np3c5wys8sz8lkj8g4r42d&dl=0I had a hard time getting the loop compensation right, but that turnedout to be mostly a dumb mistake and a mediocre data sheet. It simscrazy slow so some of the oddities are hacks to speed it up.

https://www.edn.com/high-voltage-feed-forward/

Cheers

Ignoring the hyperbolic text, I don't see a great advantage to that.
Here's my latest version:

https://www.dropbox.com/scl/fi/kn68w69oyggbrb1cf4fyv/T820_PS_4.jpg?rlkey=1upe3t5pgyulp373mae4wiskx&raw=1

It has nice dynamics and can't make more than 650 volts no matter
what's programmed; that protects the GaN fets it will drive.

Here's an isolated (transformer coupled) output pulse into 50 ohms:

https://www.dropbox.com/scl/fi/w05ji6rtj2cq1w6sva72p/IMG_7031.jpg?rlkey=58qloz9h8r8yxcpwblrl3mw6q&raw=1

It's little ratty, good enough, but we think we can pretty it up in a
production version.

Those pulses are 8.5 KW but low energy and at 1 KHz, low power. But we
keep blowing out attenuators, even 20 watt ones.

Could be internal arcing in the cermet. That'll have a lower energy >threshold than thermal.

Low rep rates help, but 100 Hz into a sampling scope is really
tedious.

Yup. Back in my antenna-coupled tunnel junction days, I was using a
20-Hz pulsed laser with lousy pulse-to-pulse energy stability, so it
took the best part of an hour to get one trace (512 points) with 100 >averages.

My intern loves my old Tek 11802. He's amazed that it has a real
glass CRT *and* touch screen.

I love mine too. Have you noticed SD-24s dying lately? I have three
out of four showing "Illegal channel number".

Mine seems to be holding up. I think one can move the eprom from a
dead SD24 into another one, maybe even copy one.

Fortunately I have these little 60-ps TDR modules that we've made, but
they aren't as flexible as SD-24s.

How do they interface?

We're designing our own PCB planar transformers for our high-voltage
GaN pulsers. I'm testing some Coilcraft planars, to learn more about
things. Even their giant 300 watt planar power trannies are amazingly
clean and fast. I use the SD24 TDR as the pulse generator and the
other channel as the secondary snooper.

https://www.dropbox.com/scl/fi/qmyfaholtrqltvl5d50ap/PL300_TDR.jpg?rlkey=h35ko8zy9mav7d63app6qrcd3&raw=1



--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: sci.electronics.design

john larkin <jl@glen--canyon.com> wrote:

On Wed, 20 Aug 2025 16:52:05 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2025-08-19 11:45, john larkin wrote:

On Tue, 19 Aug 2025 10:27:26 -0400 (EDT), Martin Rid
<martin_riddle@verison.net> wrote:

john larkin <jl@glen--canyon.com> Wrote in message:r

My summer intern Enzo is designing a pulse generator and he
doesn'thave much time before school starts, so I volunteered to do
the powersupply for him.This is an ordinary slope-compensated
autotransformer-flybackCockcroft-Walton-voltage-multiplier
programmable high-v
ltage powersupply.https://www.dropbox.com/scl/fi/lzzin9qphlfh51uznaio4/T820_HV_2.jpg?rlkey=6nw9snqxyual6o06oap8t490u&raw=1https://www.dropbox.com/scl/fi/n7c3796ihw8dex289c3x0/T820_HV_2.asc?rlkey=7o1np3c5wys8sz8lkj8g4r42d&dl=0I
had a hard time getting the loop compensation right, but that
turnedout to be mostly a dumb mistake and a mediocre data sheet. It
simscrazy slow so some of the oddities are hacks to speed it up.

https://www.edn.com/high-voltage-feed-forward/

Cheers

Ignoring the hyperbolic text, I don't see a great advantage to that.
Here's my latest version:

https://www.dropbox.com/scl/fi/kn68w69oyggbrb1cf4fyv/T820_PS_4.jpg?rlkey=1upe3t5pgyulp373mae4wiskx&raw=1

It has nice dynamics and can't make more than 650 volts no matter
what's programmed; that protects the GaN fets it will drive.

Here's an isolated (transformer coupled) output pulse into 50 ohms:

https://www.dropbox.com/scl/fi/w05ji6rtj2cq1w6sva72p/IMG_7031.jpg?rlkey=58qloz9h8r8yxcpwblrl3mw6q&raw=1

It's little ratty, good enough, but we think we can pretty it up in a
production version.

Those pulses are 8.5 KW but low energy and at 1 KHz, low power. But we
keep blowing out attenuators, even 20 watt ones.

Could be internal arcing in the cermet. That'll have a lower energy
threshold than thermal.

Low rep rates help, but 100 Hz into a sampling scope is really
tedious.

Yup. Back in my antenna-coupled tunnel junction days, I was using a
20-Hz pulsed laser with lousy pulse-to-pulse energy stability, so it
took the best part of an hour to get one trace (512 points) with 100
averages.

My intern loves my old Tek 11802. He's amazed that it has a real
glass CRT *and* touch screen.

I love mine too. Have you noticed SD-24s dying lately? I have three
out of four showing "Illegal channel number".

Mine seems to be holding up. I think one can move the eprom from a
dead SD24 into another one, maybe even copy one.

Fortunately I have these little 60-ps TDR modules that we've made, but
they aren't as flexible as SD-24s.

How do they interface?

Plain UART for the OEM version, with USB serial and RS485 as options.

ThererCOs also a super simple, self-timed analog moderCoit puts out a 1E7:1 time stretched replica of the TDR trace, i.e. 1 ps becomes 10 us. Dead
useful.

ThererCOs a configurable delay line that sets the Rx pulse width. That lets
us trade off time resolution vs. scan speed. (In order for the sampling
loop to converge at each delay value, if the pulses are narrow, you need
more of them.)

IrCOll send you one to play with if yourCOre interested.

We're designing our own PCB planar transformers for our high-voltage
GaN pulsers. I'm testing some Coilcraft planars, to learn more about
things. Even their giant 300 watt planar power trannies are amazingly
clean and fast. I use the SD24 TDR as the pulse generator and the
other channel as the secondary snooper.

I do that for diode lasers. Works great.

https://www.dropbox.com/scl/fi/qmyfaholtrqltvl5d50ap/PL300_TDR.jpg?rlkey=h35ko8zy9mav7d63app6qrcd3&raw=1

Cheers

Phil Hobbs
--
Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: sci.electronics.design

On Wed, 20 Aug 2025 16:52:05 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

On 2025-08-19 11:45, john larkin wrote:

On Tue, 19 Aug 2025 10:27:26 -0400 (EDT), Martin Rid
<martin_riddle@verison.net> wrote:

john larkin <jl@glen--canyon.com> Wrote in message:r

My summer intern Enzo is designing a pulse generator and he doesn'thave much time before school starts, so I volunteered to do the powersupply for him.This is an ordinary slope-compensated autotransformer-flybackCockcroft-Walton-voltage-multiplier programmable high-voltage powersupply.https://www.dropbox.com/scl/fi/lzzin9qphlfh51uznaio4/T820_HV_2.jpg?rlkey=6nw9snqxyual6o06oap8t490u&raw=1https://www.dropbox.com/scl/fi/n7c3796ihw8dex289c3x0/T820_HV_2.asc?rlkey=7o1np3c5wys8sz8lkj8g4r42d&dl=0I had a hard time getting the loop compensation right, but that turnedout to be mostly a dumb mistake and a mediocre data sheet. It simscrazy slow so some of the oddities are hacks to speed it up.

https://www.edn.com/high-voltage-feed-forward/

Cheers

Ignoring the hyperbolic text, I don't see a great advantage to that.
Here's my latest version:

https://www.dropbox.com/scl/fi/kn68w69oyggbrb1cf4fyv/T820_PS_4.jpg?rlkey=1upe3t5pgyulp373mae4wiskx&raw=1

It has nice dynamics and can't make more than 650 volts no matter
what's programmed; that protects the GaN fets it will drive.

Here's an isolated (transformer coupled) output pulse into 50 ohms:

https://www.dropbox.com/scl/fi/w05ji6rtj2cq1w6sva72p/IMG_7031.jpg?rlkey=58qloz9h8r8yxcpwblrl3mw6q&raw=1

It's little ratty, good enough, but we think we can pretty it up in a
production version.

Those pulses are 8.5 KW but low energy and at 1 KHz, low power. But we
keep blowing out attenuators, even 20 watt ones.

Could be internal arcing in the cermet. That'll have a lower energy >threshold than thermal.

Low rep rates help, but 100 Hz into a sampling scope is really
tedious.

Yup. Back in my antenna-coupled tunnel junction days, I was using a
20-Hz pulsed laser with lousy pulse-to-pulse energy stability, so it
took the best part of an hour to get one trace (512 points) with 100 >averages.

My intern loves my old Tek 11802. He's amazed that it has a real
glass CRT *and* touch screen.

I love mine too. Have you noticed SD-24s dying lately? I have three
out of four showing "Illegal channel number".

Fortunately I have these little 60-ps TDR modules that we've made, but
they aren't as flexible as SD-24s.

Cheers

Phil Hobbs

I ordered two new 20-watt attenuators on Tuesday and my guys blew them
out on Wednesday, hours after the UPS guy delivered. He grabbed a
couple fistfulls of candy on his way out.

We got a 1 GHz Rigol scope so we don't have to use the sampler, so we
were running at 20 Hz or something like that. Tiny average power and microjoules per shot.

I'm going to have to make my own attenuators. Not pi or tee but
probably something else. Needn't be symmetric. I'm thinking 15 or
maybe 16 resistors.

--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: sci.electronics.design

On 8/21/2025 7:40 AM, john larkin wrote:

I ordered two new 20-watt attenuators on Tuesday and my guys blew them
out on Wednesday, hours after the UPS guy delivered. He grabbed a
couple fistfulls of candy on his way out.

Time to seed some Feen-A-Mint gum into the candy dish next time the truck pulls up?

What can brown do for you? ... to you?
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: sci.electronics.design

On Thu, 21 Aug 2025 09:28:28 -0700, Buzz McCool
<buzz_mccool@yahoo.com> wrote:

On 8/21/2025 7:40 AM, john larkin wrote:

I ordered two new 20-watt attenuators on Tuesday and my guys blew them
out on Wednesday, hours after the UPS guy delivered. He grabbed a
couple fistfulls of candy on his way out.

Time to seed some Feen-A-Mint gum into the candy dish next time the truck pulls up?

No, we encourage all our service people to take treats. Candy,
cookies, chips.

--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: sci.electronics.design

On 8/21/2025 10:01 AM, john larkin wrote:

No, we encourage all our service people to take treats. Candy,
cookies, chips.

OK, sorry. I thought you were complaining about getting cleaned out of lagniappe meant for customers.

--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: sci.electronics.design

On Fri, 22 Aug 2025 08:51:18 -0700, Buzz McCool
<buzz_mccool@yahoo.com> wrote:

On 8/21/2025 10:01 AM, john larkin wrote:

No, we encourage all our service people to take treats. Candy,
cookies, chips.

OK, sorry. I thought you were complaining about getting cleaned out of lagniappe meant for customers.

Great word, lagniappe. When I was a kid we'd buy some candy and ask
for lagniappe, which was roughly a free 10% bonus, or the 13th donut
out of a dozen.

--- Synchronet 3.21a-Linux NewsLink 1.2