PSU Design...

[Cursitor Doom]

Gentlemen,

I know this will upset and disappoint a certain antipodean contributor
here, but I would like, if I may, to discuss electronic design for a
moment.

This concerns a linear power supply regulator board from a Tek 7000
series scope. Some of you may recall my infatuation with vintage test
gear and this is the latest subject for attention. This board produces
the following voltages: +130V, +50V, -50V, +15V, -15V and +5V
(regulated with feedback sensing from the downstream circuitry).

The first question I have is why would the designer come up with this
scheme where there are multiple interdependencies between the 6 output
voltages? It makes the troubleshooting so much more difficult when
something eventually goes \'phut\' and the magic smoke is released.
The second question is, I don\'t give a damn about keeping things
original, so would it be feasible to replace this rat\'s nest with 6
separate monolithic IC regulators to produce the 6 output voltages
required here? (I know it\'s \"feasible\" to do this, I just wondered
what the Panel thinks of it as solutions go).

Here\'s the schematic:

https://tinyurl.com/4m8ffw7e

 

[John Larkin]

On Mon, 01 May 2023 19:46:41 +0100, Cursitor Doom <cd@notformail.com>
wrote:

Gentlemen,

I know this will upset and disappoint a certain antipodean contributor
here, but I would like, if I may, to discuss electronic design for a
moment.

This concerns a linear power supply regulator board from a Tek 7000
series scope. Some of you may recall my infatuation with vintage test
gear and this is the latest subject for attention. This board produces
the following voltages: +130V, +50V, -50V, +15V, -15V and +5V
(regulated with feedback sensing from the downstream circuitry).

The first question I have is why would the designer come up with this
scheme where there are multiple interdependencies between the 6 output
voltages? It makes the troubleshooting so much more difficult when
something eventually goes \'phut\' and the magic smoke is released.
The second question is, I don\'t give a damn about keeping things
original, so would it be feasible to replace this rat\'s nest with 6
separate monolithic IC regulators to produce the 6 output voltages
required here? (I know it\'s \"feasible\" to do this, I just wondered
what the Panel thinks of it as solutions go).

Here\'s the schematic:

https://tinyurl.com/4m8ffw7e

There aren\'t very many switcher or linear reg chips that accept more
than about 30 volts. Many, a lot less.

Can you post the old schematic?

I have that issue now, namely a +48 buss and a need for a bunch of
small switchers. I like the old LM2576HV-ADJ - quiet and reliable -
but it\'s big and switches at 52 KHz so needs a giant inductor and
caps.

7000 series is too modern for me. I like the 547 and the 11802.

 

[Phil Hobbs]

On 2023-05-01 15:09, John Larkin wrote:

On Mon, 01 May 2023 19:46:41 +0100, Cursitor Doom <cd@notformail.com
wrote:

Gentlemen,

I know this will upset and disappoint a certain antipodean contributor
here, but I would like, if I may, to discuss electronic design for a
moment.

This concerns a linear power supply regulator board from a Tek 7000
series scope. Some of you may recall my infatuation with vintage test
gear and this is the latest subject for attention. This board produces
the following voltages: +130V, +50V, -50V, +15V, -15V and +5V
(regulated with feedback sensing from the downstream circuitry).

The first question I have is why would the designer come up with this
scheme where there are multiple interdependencies between the 6 output
voltages? It makes the troubleshooting so much more difficult when
something eventually goes \'phut\' and the magic smoke is released.
The second question is, I don\'t give a damn about keeping things
original, so would it be feasible to replace this rat\'s nest with 6
separate monolithic IC regulators to produce the 6 output voltages
required here? (I know it\'s \"feasible\" to do this, I just wondered
what the Panel thinks of it as solutions go).

Here\'s the schematic:

https://tinyurl.com/4m8ffw7e

There aren\'t very many switcher or linear reg chips that accept more
than about 30 volts. Many, a lot less.

Can you post the old schematic?

I have that issue now, namely a +48 buss and a need for a bunch of
small switchers. I like the old LM2576HV-ADJ - quiet and reliable -
but it\'s big and switches at 52 KHz so needs a giant inductor and
caps.

The 150-kHz and 250-kHz Simple Switchers are pretty good, and let you
use much smaller passives. I use the LM2596 and LM2672. The genuine TI
ones aren\'t what you\'d call cheap.

7000 series is too modern for me. I like the 547 and the 11802.

I have a couple of TDS 784As, one on the bench and one in a rack next to
it. The slow control response takes a bit of getting used to, but
they\'re generally very good. 1 GHz, 4 GSa/s is pretty useful.

Of course their FFTs and so on are pretty slow, but they\'re probably
running a 68020 or something inside.

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

 

[Cursitor Doom]

On Mon, 01 May 2023 12:09:53 -0700, John Larkin
<jlarkin@highlandSNIPMEtechnology.com> wrote:

On Mon, 01 May 2023 19:46:41 +0100, Cursitor Doom <cd@notformail.com
wrote:

Gentlemen,

I know this will upset and disappoint a certain antipodean contributor
here, but I would like, if I may, to discuss electronic design for a
moment.

This concerns a linear power supply regulator board from a Tek 7000
series scope. Some of you may recall my infatuation with vintage test
gear and this is the latest subject for attention. This board produces
the following voltages: +130V, +50V, -50V, +15V, -15V and +5V
(regulated with feedback sensing from the downstream circuitry).

The first question I have is why would the designer come up with this
scheme where there are multiple interdependencies between the 6 output
voltages? It makes the troubleshooting so much more difficult when
something eventually goes \'phut\' and the magic smoke is released.
The second question is, I don\'t give a damn about keeping things
original, so would it be feasible to replace this rat\'s nest with 6
separate monolithic IC regulators to produce the 6 output voltages
required here? (I know it\'s \"feasible\" to do this, I just wondered
what the Panel thinks of it as solutions go).

Here\'s the schematic:

https://tinyurl.com/4m8ffw7e

There aren\'t very many switcher or linear reg chips that accept more
than about 30 volts. Many, a lot less.

Can you post the old schematic?

The *old* schematic? What old schematic, John?

I have that issue now, namely a +48 buss and a need for a bunch of
small switchers. I like the old LM2576HV-ADJ - quiet and reliable -
but it\'s big and switches at 52 KHz so needs a giant inductor and
caps.

7000 series is too modern for me. I like the 547 and the 11802.

 

[John Larkin]

On Mon, 01 May 2023 22:17:52 +0100, Cursitor Doom <cd@notformail.com>
wrote:

On Mon, 01 May 2023 12:09:53 -0700, John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote:

On Mon, 01 May 2023 19:46:41 +0100, Cursitor Doom <cd@notformail.com
wrote:

Gentlemen,

I know this will upset and disappoint a certain antipodean contributor
here, but I would like, if I may, to discuss electronic design for a
moment.

This concerns a linear power supply regulator board from a Tek 7000
series scope. Some of you may recall my infatuation with vintage test
gear and this is the latest subject for attention. This board produces
the following voltages: +130V, +50V, -50V, +15V, -15V and +5V
(regulated with feedback sensing from the downstream circuitry).

The first question I have is why would the designer come up with this
scheme where there are multiple interdependencies between the 6 output
voltages? It makes the troubleshooting so much more difficult when
something eventually goes \'phut\' and the magic smoke is released.
The second question is, I don\'t give a damn about keeping things
original, so would it be feasible to replace this rat\'s nest with 6
separate monolithic IC regulators to produce the 6 output voltages
required here? (I know it\'s \"feasible\" to do this, I just wondered
what the Panel thinks of it as solutions go).

Here\'s the schematic:

https://tinyurl.com/4m8ffw7e

There aren\'t very many switcher or linear reg chips that accept more
than about 30 volts. Many, a lot less.

Can you post the old schematic?

The *old* schematic? What old schematic, John?

Oops, missed that link.

It is a real hairball. Do you really want to fix it?

I guess it\'s a 60 Hz transformer, not a switcher.

You\'d have to know the load currents to redesign the regs.

Do the supplies really need remote sense? That shoots down a lot of
simple approaches.

Color digital scopes are great. Fast, cheap, light, run cool, have
storage and signal averaging, show the volts and time ranges, and none
of ours have failed so far. And they show traces in color! Monochrome
scopes confuse me now.

 

[Cursitor Doom]

On Mon, 01 May 2023 15:11:12 -0700, John Larkin
<jlarkin@highlandSNIPMEtechnology.com> wrote:

On Mon, 01 May 2023 22:17:52 +0100, Cursitor Doom <cd@notformail.com
wrote:

On Mon, 01 May 2023 12:09:53 -0700, John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote:

On Mon, 01 May 2023 19:46:41 +0100, Cursitor Doom <cd@notformail.com
wrote:

Gentlemen,

I know this will upset and disappoint a certain antipodean contributor
here, but I would like, if I may, to discuss electronic design for a
moment.

This concerns a linear power supply regulator board from a Tek 7000
series scope. Some of you may recall my infatuation with vintage test
gear and this is the latest subject for attention. This board produces
the following voltages: +130V, +50V, -50V, +15V, -15V and +5V
(regulated with feedback sensing from the downstream circuitry).

The first question I have is why would the designer come up with this
scheme where there are multiple interdependencies between the 6 output
voltages? It makes the troubleshooting so much more difficult when
something eventually goes \'phut\' and the magic smoke is released.
The second question is, I don\'t give a damn about keeping things
original, so would it be feasible to replace this rat\'s nest with 6
separate monolithic IC regulators to produce the 6 output voltages
required here? (I know it\'s \"feasible\" to do this, I just wondered
what the Panel thinks of it as solutions go).

Here\'s the schematic:

https://tinyurl.com/4m8ffw7e

There aren\'t very many switcher or linear reg chips that accept more
than about 30 volts. Many, a lot less.

Can you post the old schematic?

The *old* schematic? What old schematic, John?

Oops, missed that link.

It is a real hairball. Do you really want to fix it?

Ideally, yes. However, harsh experience has taught me that the next
\"phut!\" is seldom far away. These components are now half a century or
more old and even if they don\'t fail, their values drift over time,
eventually out of spec so it\'s strictly a labour of love.

>I guess it\'s a 60 Hz transformer, not a switcher.

Yes, I mentioned in the description it\'s a linear PSU, but If I\'d have
posted the complete schematic that would have been far more evident.
My bad.

>You\'d have to know the load currents to redesign the regs.

Indeed, yes. However, I can get those from a fellow enthusiast who
keeps data on that kind of thing.

Do the supplies really need remote sense? That shoots down a lot of
simple approaches.

I\'m not sure, John. You\'re right, though, it would be much simpler if
they were not needed.

Color digital scopes are great. Fast, cheap, light, run cool, have
storage and signal averaging, show the volts and time ranges, and none
of ours have failed so far. And they show traces in color! Monochrome
scopes confuse me now.

I know, I know. I really should get one and it\'s not as if I can\'t
afford it. But I\'m kind of wedded to the CRT type for nostaligic
reasons and the bond is very strong! You still rate Rigol highly? Any
others?

 

[Tabby]

On Monday, 1 May 2023 at 20:10:10 UTC+1, John Larkin wrote:

On Mon, 01 May 2023 19:46:41 +0100, Cursitor Doom <c...@notformail.com
wrote:
Gentlemen,

I know this will upset and disappoint a certain antipodean contributor
here, but I would like, if I may, to discuss electronic design for a
moment.

This concerns a linear power supply regulator board from a Tek 7000
series scope. Some of you may recall my infatuation with vintage test
gear and this is the latest subject for attention. This board produces
the following voltages: +130V, +50V, -50V, +15V, -15V and +5V
(regulated with feedback sensing from the downstream circuitry).

The first question I have is why would the designer come up with this
scheme where there are multiple interdependencies between the 6 output
voltages? It makes the troubleshooting so much more difficult when
something eventually goes \'phut\' and the magic smoke is released.
The second question is, I don\'t give a damn about keeping things
original, so would it be feasible to replace this rat\'s nest with 6
separate monolithic IC regulators to produce the 6 output voltages
required here? (I know it\'s \"feasible\" to do this, I just wondered
what the Panel thinks of it as solutions go).

Here\'s the schematic:

https://tinyurl.com/4m8ffw7e
There aren\'t very many switcher or linear reg chips that accept more
than about 30 volts. Many, a lot less.

but pass transistors can

I\'m almost tempted to ask why the psu lines are interdependant.

 

[Cursitor Doom]

On Mon, 1 May 2023 16:23:18 -0700 (PDT), Tabby <tabbypurr@gmail.com>
wrote:

On Monday, 1 May 2023 at 20:10:10 UTC+1, John Larkin wrote:
On Mon, 01 May 2023 19:46:41 +0100, Cursitor Doom <c...@notformail.com
wrote:
Gentlemen,

I know this will upset and disappoint a certain antipodean contributor
here, but I would like, if I may, to discuss electronic design for a
moment.

This concerns a linear power supply regulator board from a Tek 7000
series scope. Some of you may recall my infatuation with vintage test
gear and this is the latest subject for attention. This board produces
the following voltages: +130V, +50V, -50V, +15V, -15V and +5V
(regulated with feedback sensing from the downstream circuitry).

The first question I have is why would the designer come up with this
scheme where there are multiple interdependencies between the 6 output
voltages? It makes the troubleshooting so much more difficult when
something eventually goes \'phut\' and the magic smoke is released.
The second question is, I don\'t give a damn about keeping things
original, so would it be feasible to replace this rat\'s nest with 6
separate monolithic IC regulators to produce the 6 output voltages
required here? (I know it\'s \"feasible\" to do this, I just wondered
what the Panel thinks of it as solutions go).

Here\'s the schematic:

https://tinyurl.com/4m8ffw7e
There aren\'t very many switcher or linear reg chips that accept more
than about 30 volts. Many, a lot less.

but pass transistors can

I\'m almost tempted to ask why the psu lines are interdependant.

That was one of the two questions I posed about this design. The only
thing I can think of is they were trying to save a couple of windings
from the transformer secondary to keep cost down.

 

[John Larkin]

On Mon, 01 May 2023 23:35:27 +0100, Cursitor Doom <cd@notformail.com>
wrote:

On Mon, 01 May 2023 15:11:12 -0700, John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote:

On Mon, 01 May 2023 22:17:52 +0100, Cursitor Doom <cd@notformail.com
wrote:

On Mon, 01 May 2023 12:09:53 -0700, John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote:

On Mon, 01 May 2023 19:46:41 +0100, Cursitor Doom <cd@notformail.com
wrote:

Gentlemen,

I know this will upset and disappoint a certain antipodean contributor
here, but I would like, if I may, to discuss electronic design for a
moment.

This concerns a linear power supply regulator board from a Tek 7000
series scope. Some of you may recall my infatuation with vintage test
gear and this is the latest subject for attention. This board produces
the following voltages: +130V, +50V, -50V, +15V, -15V and +5V
(regulated with feedback sensing from the downstream circuitry).

The first question I have is why would the designer come up with this
scheme where there are multiple interdependencies between the 6 output
voltages? It makes the troubleshooting so much more difficult when
something eventually goes \'phut\' and the magic smoke is released.
The second question is, I don\'t give a damn about keeping things
original, so would it be feasible to replace this rat\'s nest with 6
separate monolithic IC regulators to produce the 6 output voltages
required here? (I know it\'s \"feasible\" to do this, I just wondered
what the Panel thinks of it as solutions go).

Here\'s the schematic:

https://tinyurl.com/4m8ffw7e

There aren\'t very many switcher or linear reg chips that accept more
than about 30 volts. Many, a lot less.

Can you post the old schematic?

The *old* schematic? What old schematic, John?

Oops, missed that link.

It is a real hairball. Do you really want to fix it?

Ideally, yes. However, harsh experience has taught me that the next
\"phut!\" is seldom far away. These components are now half a century or
more old and even if they don\'t fail, their values drift over time,
eventually out of spec so it\'s strictly a labour of love.

I guess it\'s a 60 Hz transformer, not a switcher.

Yes, I mentioned in the description it\'s a linear PSU, but If I\'d have
posted the complete schematic that would have been far more evident.
My bad.

You\'d have to know the load currents to redesign the regs.

Indeed, yes. However, I can get those from a fellow enthusiast who
keeps data on that kind of thing.

Do the supplies really need remote sense? That shoots down a lot of
simple approaches.

I\'m not sure, John. You\'re right, though, it would be much simpler if
they were not needed.

Color digital scopes are great. Fast, cheap, light, run cool, have
storage and signal averaging, show the volts and time ranges, and none
of ours have failed so far. And they show traces in color! Monochrome
scopes confuse me now.

I know, I know. I really should get one and it\'s not as if I can\'t
afford it. But I\'m kind of wedded to the CRT type for nostaligic
reasons and the bond is very strong! You still rate Rigol highly? Any
others?

We mostly buy Rigol lately. A few Teks; I really like the fully
isolated TPS2024.

The Rigols have been great. My guys have developed a Python library to
talk to them for automated measurements.

My bench scope is a 4-channel 500 MHz Rigol. We bought a few of the
250 MHz versions and arm-twisted the rep to throw in the software
upgrade for free. The 250 is just a brain-damaged 500.

I think the Rigols have got more expensive since some tariff law
change.

I do love my ancient, maybe 80 pound, 11802 sampler.

 

[John Larkin]

On Mon, 1 May 2023 16:23:18 -0700 (PDT), Tabby <tabbypurr@gmail.com>
wrote:

On Monday, 1 May 2023 at 20:10:10 UTC+1, John Larkin wrote:
On Mon, 01 May 2023 19:46:41 +0100, Cursitor Doom <c...@notformail.com
wrote:
Gentlemen,

I know this will upset and disappoint a certain antipodean contributor
here, but I would like, if I may, to discuss electronic design for a
moment.

This concerns a linear power supply regulator board from a Tek 7000
series scope. Some of you may recall my infatuation with vintage test
gear and this is the latest subject for attention. This board produces
the following voltages: +130V, +50V, -50V, +15V, -15V and +5V
(regulated with feedback sensing from the downstream circuitry).

The first question I have is why would the designer come up with this
scheme where there are multiple interdependencies between the 6 output
voltages? It makes the troubleshooting so much more difficult when
something eventually goes \'phut\' and the magic smoke is released.
The second question is, I don\'t give a damn about keeping things
original, so would it be feasible to replace this rat\'s nest with 6
separate monolithic IC regulators to produce the 6 output voltages
required here? (I know it\'s \"feasible\" to do this, I just wondered
what the Panel thinks of it as solutions go).

Here\'s the schematic:

https://tinyurl.com/4m8ffw7e
There aren\'t very many switcher or linear reg chips that accept more
than about 30 volts. Many, a lot less.

but pass transistors can

I\'m almost tempted to ask why the psu lines are interdependant.

They all seem to use one another. Startup must have taken a lot of
thinking.

 

[Clifford Heath]

On 02/05/23 04:46, Cursitor Doom wrote:

Gentlemen,

I know this will upset and disappoint a certain antipodean contributor
here, but I would like, if I may, to discuss electronic design for a
moment.

This concerns a linear power supply regulator board from a Tek 7000
series scope. Some of you may recall my infatuation with vintage test
gear and this is the latest subject for attention. This board produces
the following voltages: +130V, +50V, -50V, +15V, -15V and +5V
(regulated with feedback sensing from the downstream circuitry).

The first question I have is why would the designer come up with this
scheme where there are multiple interdependencies between the 6 output
voltages? It makes the troubleshooting so much more difficult when
something eventually goes \'phut\' and the magic smoke is released.
The second question is, I don\'t give a damn about keeping things
original, so would it be feasible to replace this rat\'s nest with 6
separate monolithic IC regulators to produce the 6 output voltages
required here? (I know it\'s \"feasible\" to do this, I just wondered
what the Panel thinks of it as solutions go).

Here\'s the schematic:

https://tinyurl.com/4m8ffw7e

You\'ll get good help on the TekScopes folk on groups.io (the group split
in two - try both):

<https://groups.io/g/TekScopes>
<https://groups.io/g/TekScopes2>

I assume you already know about the TekWiki at <https://w140.com>.

Clifford Heath

 

[Anthony William Sloman]

On Tuesday, May 2, 2023 at 4:46:52 AM UTC+10, Cursitor Doom wrote:

Gentlemen,

I know this will upset and disappoint a certain antipodean contributor
here, but I would like, if I may, to discuss electronic design for a
moment.

This concerns a linear power supply regulator board from a Tek 7000
series scope. Some of you may recall my infatuation with vintage test
gear and this is the latest subject for attention. This board produces
the following voltages: +130V, +50V, -50V, +15V, -15V and +5V
(regulated with feedback sensing from the downstream circuitry).

The first question I have is why would the designer come up with this
scheme where there are multiple interdependencies between the 6 output
voltages?

Hard to say. It\'s clearly a very old design, and the schematic you\'ve posted isn\'t complete - and doesn\'t have a date on it.

There\'s no voltage reference shown anywhere on the part of the schematic you have posted, so trying to second-guess why the designer came up with what\'s shown here would be a waste of time.

It makes the troubleshooting so much more difficult when
something eventually goes \'phut\' and the magic smoke is released.

The second question is, I don\'t give a damn about keeping things
original, so would it be feasible to replace this rat\'s nest with 6
separate monolithic IC regulators to produce the 6 output voltages
required here? (I know it\'s \"feasible\" to do this, I just wondered
what the Panel thinks of it as solutions go).

The 130V output voltage isn\'t widely available. Mouser offers

https://au.mouser.com/c/semiconductors/integrated-circuits-ics/power-management-ics/voltage-regulators-voltage-controllers/?output%20voltage=800%20mV%20to%20140%20V

which is mostly Linear Technology LTC3638 switching regulators. There are others

--
Bill Sloman, Sydney

 

[boB]

On Mon, 1 May 2023 21:10:12 -0700 (PDT), Anthony William Sloman
<bill.sloman@ieee.org> wrote:

On Tuesday, May 2, 2023 at 4:46:52?AM UTC+10, Cursitor Doom wrote:
Gentlemen,

I know this will upset and disappoint a certain antipodean contributor
here, but I would like, if I may, to discuss electronic design for a
moment.

This concerns a linear power supply regulator board from a Tek 7000
series scope. Some of you may recall my infatuation with vintage test
gear and this is the latest subject for attention. This board produces
the following voltages: +130V, +50V, -50V, +15V, -15V and +5V
(regulated with feedback sensing from the downstream circuitry).

The first question I have is why would the designer come up with this
scheme where there are multiple interdependencies between the 6 output
voltages?


Hard to say. It\'s clearly a very old design, and the schematic you\'ve posted isn\'t complete - and doesn\'t have a date on it.

There\'s no voltage reference shown anywhere on the part of the schematic you have posted, so trying to second-guess why the designer came up with what\'s shown here would be a waste of time.

It makes the troubleshooting so much more difficult when
something eventually goes \'phut\' and the magic smoke is released.

The second question is, I don\'t give a damn about keeping things
original, so would it be feasible to replace this rat\'s nest with 6
separate monolithic IC regulators to produce the 6 output voltages
required here? (I know it\'s \"feasible\" to do this, I just wondered
what the Panel thinks of it as solutions go).

The 130V output voltage isn\'t widely available. Mouser offers

https://au.mouser.com/c/semiconductors/integrated-circuits-ics/power-management-ics/voltage-regulators-voltage-controllers/?output%20voltage=800%20mV%20to%20140%20V

which is mostly Linear Technology LTC3638 switching regulators. There are others

When I need a semi high voltage output or input from HV and not too
much dissipation, I just take an N channel FET in source-follower
configuration with a zener diode (V = Vout + VgsTh) from gate to GND
and a high-ish value gate to HV bias resistor. If independence of
output voltage is important, you could just add more of these
circuits.

boB

 

[Anthony William Sloman]

On Tuesday, May 2, 2023 at 2:49:41 PM UTC+10, boB wrote:

On Mon, 1 May 2023 21:10:12 -0700 (PDT), Anthony William Sloman
bill....@ieee.org> wrote:
On Tuesday, May 2, 2023 at 4:46:52?AM UTC+10, Cursitor Doom wrote:

I know this will upset and disappoint a certain antipodean contributor
here, but I would like, if I may, to discuss electronic design for a
moment.

This concerns a linear power supply regulator board from a Tek 7000
series scope. Some of you may recall my infatuation with vintage test
gear and this is the latest subject for attention. This board produces
the following voltages: +130V, +50V, -50V, +15V, -15V and +5V
(regulated with feedback sensing from the downstream circuitry).

The first question I have is why would the designer come up with this
scheme where there are multiple interdependencies between the 6 output
voltages?


Hard to say. It\'s clearly a very old design, and the schematic you\'ve posted isn\'t complete - and doesn\'t have a date on it.

There\'s no voltage reference shown anywhere on the part of the schematic you have posted, so trying to second-guess why the designer came up with what\'s shown here would be a waste of time.

It makes the troubleshooting so much more difficult when
something eventually goes \'phut\' and the magic smoke is released.

The second question is, I don\'t give a damn about keeping things
original, so would it be feasible to replace this rat\'s nest with 6
separate monolithic IC regulators to produce the 6 output voltages
required here? (I know it\'s \"feasible\" to do this, I just wondered
what the Panel thinks of it as solutions go).

The 130V output voltage isn\'t widely available. Mouser offers

https://au.mouser.com/c/semiconductors/integrated-circuits-ics/power-management-ics/voltage-regulators-voltage-controllers/?output%20voltage=800%20mV%20to%20140%20V

which is mostly Linear Technology LTC3638 switching regulators. There are others

When I need a semi high voltage output or input from HV and not too
much dissipation, I just take an N channel FET in source-follower
configuration with a zener diode (V = Vout + VgsTh) from gate to GND
and a high-ish value gate to HV bias resistor. If independence of
output voltage is important, you could just add more of these
circuits.

That kind of advice assumes a certain amount of electronic competence in the person being advised. You are talking to Cursitor Doom, who doesn\'t have it.

Linear Technology parts come with pretty fool-proof data sheets.

--
Bill Sloman, Sydney

 

[legg]

On Mon, 01 May 2023 19:46:41 +0100, Cursitor Doom <cd@notformail.com>
wrote:

Gentlemen,

I know this will upset and disappoint a certain antipodean contributor
here, but I would like, if I may, to discuss electronic design for a
moment.

This concerns a linear power supply regulator board from a Tek 7000
series scope. Some of you may recall my infatuation with vintage test
gear and this is the latest subject for attention. This board produces
the following voltages: +130V, +50V, -50V, +15V, -15V and +5V
(regulated with feedback sensing from the downstream circuitry).

The first question I have is why would the designer come up with this
scheme where there are multiple interdependencies between the 6 output
voltages? It makes the troubleshooting so much more difficult when
something eventually goes \'phut\' and the magic smoke is released.
The second question is, I don\'t give a damn about keeping things
original, so would it be feasible to replace this rat\'s nest with 6
separate monolithic IC regulators to produce the 6 output voltages
required here? (I know it\'s \"feasible\" to do this, I just wondered
what the Panel thinks of it as solutions go).

Here\'s the schematic:

https://tinyurl.com/4m8ffw7e

I don\'t see a lot of interdependence, just a lack of
integration, which is typical of the date of mfr.

Do whatever you want, wiseguy. You\'ll find out.

RL

 

[Fred Bloggs]

On Monday, May 1, 2023 at 2:46:52 PM UTC-4, Cursitor Doom wrote:

Gentlemen,

I know this will upset and disappoint a certain antipodean contributor
here, but I would like, if I may, to discuss electronic design for a
moment.

This concerns a linear power supply regulator board from a Tek 7000
series scope. Some of you may recall my infatuation with vintage test
gear and this is the latest subject for attention. This board produces
the following voltages: +130V, +50V, -50V, +15V, -15V and +5V
(regulated with feedback sensing from the downstream circuitry).

The first question I have is why would the designer come up with this
scheme where there are multiple interdependencies between the 6 output
voltages? It makes the troubleshooting so much more difficult when
something eventually goes \'phut\' and the magic smoke is released.
The second question is, I don\'t give a damn about keeping things
original, so would it be feasible to replace this rat\'s nest with 6
separate monolithic IC regulators to produce the 6 output voltages
required here? (I know it\'s \"feasible\" to do this, I just wondered
what the Panel thinks of it as solutions go).

Here\'s the schematic:

https://tinyurl.com/4m8ffw7e

It\'s actually a very simplified design. The higher 130V simplifies a lot of biasing, and, whatever its final destination, the load, due to feedback, is impervious to deviations from nominal. A lot of the lower voltage circuitry is using it for current source biases all over the place. It\'s actually a simplified design, and should be relatively noise free. Any components that failed due to age are probably the electrolytics, the semiconductors should last.
Interdependencies make a lot of sense in situations requiring controlled power sequencing for circuits requiring multiple voltages that can be damaged if one of them is missing.

 

[Fred Bloggs]

On Tuesday, May 2, 2023 at 12:10:16 AM UTC-4, Anthony William Sloman wrote:

On Tuesday, May 2, 2023 at 4:46:52 AM UTC+10, Cursitor Doom wrote:
Gentlemen,

I know this will upset and disappoint a certain antipodean contributor
here, but I would like, if I may, to discuss electronic design for a
moment.

This concerns a linear power supply regulator board from a Tek 7000
series scope. Some of you may recall my infatuation with vintage test
gear and this is the latest subject for attention. This board produces
the following voltages: +130V, +50V, -50V, +15V, -15V and +5V
(regulated with feedback sensing from the downstream circuitry).

The first question I have is why would the designer come up with this
scheme where there are multiple interdependencies between the 6 output
voltages?
Hard to say. It\'s clearly a very old design, and the schematic you\'ve posted isn\'t complete - and doesn\'t have a date on it.

Makes no difference, it\'s still golden.

There\'s no voltage reference shown anywhere on the part of the schematic you have posted, so trying to second-guess why the designer came up with what\'s shown here would be a waste of time.

Those things that look like diodes with designator \'VR\' are zeners, VR means voltage reference.

It makes the troubleshooting so much more difficult when
something eventually goes \'phut\' and the magic smoke is released.

The second question is, I don\'t give a damn about keeping things
original, so would it be feasible to replace this rat\'s nest with 6
separate monolithic IC regulators to produce the 6 output voltages
required here? (I know it\'s \"feasible\" to do this, I just wondered
what the Panel thinks of it as solutions go).
The 130V output voltage isn\'t widely available. Mouser offers

https://au.mouser.com/c/semiconductors/integrated-circuits-ics/power-management-ics/voltage-regulators-voltage-controllers/?output%20voltage=800%20mV%20to%20140%20V

which is mostly Linear Technology LTC3638 switching regulators. There are others

--
Bill Sloman, Sydney

 

[John Larkin]

On Tue, 2 May 2023 10:56:14 -0700 (PDT), Fred Bloggs
<bloggs.fredbloggs.fred@gmail.com> wrote:

On Tuesday, May 2, 2023 at 12:10:16?AM UTC-4, Anthony William Sloman wrote:
On Tuesday, May 2, 2023 at 4:46:52?AM UTC+10, Cursitor Doom wrote:
Gentlemen,

I know this will upset and disappoint a certain antipodean contributor
here, but I would like, if I may, to discuss electronic design for a
moment.

This concerns a linear power supply regulator board from a Tek 7000
series scope. Some of you may recall my infatuation with vintage test
gear and this is the latest subject for attention. This board produces
the following voltages: +130V, +50V, -50V, +15V, -15V and +5V
(regulated with feedback sensing from the downstream circuitry).

The first question I have is why would the designer come up with this
scheme where there are multiple interdependencies between the 6 output
voltages?
Hard to say. It\'s clearly a very old design, and the schematic you\'ve posted isn\'t complete - and doesn\'t have a date on it.

Makes no difference, it\'s still golden.


There\'s no voltage reference shown anywhere on the part of the schematic you have posted, so trying to second-guess why the designer came up with what\'s shown here would be a waste of time.

Those things that look like diodes with designator \'VR\' are zeners, VR means voltage reference.

The CR things are crystal rectifiers.

In those days, D meant dynamotor, a type of dc/dc converter.

 

[Fred Bloggs]

On Tuesday, May 2, 2023 at 2:43:17 PM UTC-4, John Larkin wrote:

On Tue, 2 May 2023 10:56:14 -0700 (PDT), Fred Bloggs
bloggs.fred...@gmail.com> wrote:

On Tuesday, May 2, 2023 at 12:10:16?AM UTC-4, Anthony William Sloman wrote:
On Tuesday, May 2, 2023 at 4:46:52?AM UTC+10, Cursitor Doom wrote:
Gentlemen,

I know this will upset and disappoint a certain antipodean contributor
here, but I would like, if I may, to discuss electronic design for a
moment.

This concerns a linear power supply regulator board from a Tek 7000
series scope. Some of you may recall my infatuation with vintage test
gear and this is the latest subject for attention. This board produces
the following voltages: +130V, +50V, -50V, +15V, -15V and +5V
(regulated with feedback sensing from the downstream circuitry).

The first question I have is why would the designer come up with this
scheme where there are multiple interdependencies between the 6 output
voltages?
Hard to say. It\'s clearly a very old design, and the schematic you\'ve posted isn\'t complete - and doesn\'t have a date on it.

Makes no difference, it\'s still golden.


There\'s no voltage reference shown anywhere on the part of the schematic you have posted, so trying to second-guess why the designer came up with what\'s shown here would be a waste of time.

Those things that look like diodes with designator \'VR\' are zeners, VR means voltage reference.
The CR things are crystal rectifiers.

In those days, D meant dynamotor, a type of dc/dc converter.

I don\'t think the circuit is that old. It post dates the invention of the transistor. Probably designed in the 70s.

 

[three_jeeps]

On Monday, May 1, 2023 at 6:35:36 PM UTC-4, Cursitor Doom wrote:

On Mon, 01 May 2023 15:11:12 -0700, John Larkin
jla...@highlandSNIPMEtechnology.com> wrote:

On Mon, 01 May 2023 22:17:52 +0100, Cursitor Doom <c...@notformail.com
wrote:
I know, I know. I really should get one and it\'s not as if I can\'t

afford it. But I\'m kind of wedded to the CRT type for nostaligic
reasons and the bond is very strong! You still rate Rigol highly? Any
others?


I really like my Keysight 3000 A 1GHZ scope but it cost a small fortune...Last year I got a Siglent sds1104x-e and am amazed at all the capability it has, for $500USD. Get the 100MHz version and apply the free upgrade hack that takes it to 200MHz. Scope has 30+ math functions, 4 channel, I2c/RS232/SPI/uart decoding etc. It doesn\'t have external sync.... There are Rigols in a similar price range with similar functionality (I think the Rigol has ext sync).