Author Topic: 0-350V 0.2A Bench Power Supply  (Read 9441 times)

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Offline 001

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Re: Looking for yours opinions! HV bench power supply
« Reply #50 on: November 20, 2017, 07:44:25 PM »
If you are not a tube fan, why do you need a high voltage bench power supply ?

i work with homebrewed polymer films
« Last Edit: November 20, 2017, 07:47:06 PM by 001 »
 

Offline prasimix

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Re: Looking for yours opinions! HV bench power supply
« Reply #51 on: November 20, 2017, 07:56:52 PM »
How "EMI" issue (many times synonymously taken for "ripple and noise" too) is then applicable for such type of application? If "not" (since today you can find "switchers" in many sensitive devices) maybe you should really start consider some switcher topology.
Maybe you can take a look at SEPIC/cuk topologies (that are inherently "lower noise"), an example can be found in LTC app-note/journal 84 (page 146). It's CV/CC SEPIC power supply with "only" 0-100 V, but that range can be easily extended to 0-350 V and beyond. Please note that input is low voltage e.g. 48 Vdc (or anything in that range). Another "harder switching" topology that is AFAIK heavily employed in solar harvesting solutions is current-fed push pull converter (could be with single or dual inductor). With it you can easily goes anywhere up to few kV and (kW too) with proper transformer (and experience/knowledge).
« Last Edit: November 20, 2017, 07:59:06 PM by prasimix »
 
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Offline oldway

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Re: Looking for yours opinions! HV bench power supply
« Reply #52 on: November 20, 2017, 08:18:17 PM »
With this kind of application, do you really need regulated output ?
What about a variac with isolation transformer, a circuit breaker, a bridge rectifier and an electrolytic capacitor (with discharge resistor for safety) ?
 

Offline 001

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Re: Looking for yours opinions! HV bench power supply
« Reply #53 on: November 20, 2017, 08:28:05 PM »
I`m aware from swichers since I don`t know how to buid realy "quiet" ones  :-//

P.S. simple variac and rectifier is not ok becouse ripple voltage so high and no way to current limit
Previous tube linear supply was ok but it is wery large, hot and in fact kind of antique crap (almost all parts was needs to replacement)
all I need is to clone it with a new parts (i yet pic new industrial grade siemens [email protected] transformer) and transistors
 

Offline prasimix

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Re: Looking for yours opinions! HV bench power supply
« Reply #54 on: November 20, 2017, 08:31:18 PM »
I`m aware from swichers since I don`t know how to buid realy "quiet" ones  :-//

Ok, if you decide to be more specific I believe that you can count on more valuable feedback about "quietness" from many members of this forum :)
 

Offline 001

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Re: Looking for yours opinions! HV bench power supply
« Reply #55 on: November 20, 2017, 08:39:14 PM »
The most common switching supply topology in diy internet is terrible in ripple and emi sence
I`m not experienced in high grade PS and I have no ideas to do it
can You post some links about quiet ps shematics? 300mV ripple voltage at [email protected] will be affordable
 

Offline prasimix

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Re: Looking for yours opinions! HV bench power supply
« Reply #56 on: November 20, 2017, 08:48:22 PM »
I just posted one :). I can bet that LTC's SEPIC could go easily below that 300 mV. Going from 0-100 to 350 V shouldn't be an issue. Actually in one or other way be prepared to spend some time and energy in finding "ready to go" SEPIC transformer or to make a custom one.
As ready-made solution maybe you should consider transformers with multiple windings such as WE-FLEX+ that comes in many forms (i.e. base inductance and current). You can also try to navigate list of ready-made transformers from Feryster (available thru TME.eu).
 
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Offline oldway

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Offline 001

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« Last Edit: November 20, 2017, 09:44:48 PM by 001 »
 

Offline oldway

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Re: Looking for yours opinions! HV bench power supply
« Reply #59 on: November 20, 2017, 09:53:52 PM »
Another solution:

http://www.advanceproductservices.co.uk/data/E350.pdf

My opinion ?
I prefer to trust in my EL34 option.... :-DD

I was making vacuum tube audio amplifiers in the past....this may explain my opinion.  :-DD
 
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Offline 001

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Re: Looking for yours opinions! HV bench power supply
« Reply #60 on: November 20, 2017, 10:01:36 PM »
It should be developed, or you have to use a vacuum tube scheme like the BED-002 that I have already posted with some modifications for a higher current.

I unfortunately do not have time to take care of it because I am doing repairs of vintage audio devices and I have dozens of devices waiting for repairs.

EDIT: with 4 x EL34 and 400V rectified voltage, you can make a 50V to 350V ajustable power supply 250 mA without any pre-regulator.

You spend a lot of time here/ Thanx!!
Can You post shematic of YOURS OWN HV PS? The PS You daily use
 

Offline oldway

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Re: Looking for yours opinions! HV bench power supply
« Reply #61 on: November 20, 2017, 10:09:40 PM »
Also Fug SMPS Model MCP 140-350 , very good, I already had one....

0 - 350V 400 mA.

http://www.fug-elektronik.de/en/files/259000/FuG_Catalogue.pdf

When I was developing tubes audio amplifiers, I was using an adjustable (multi taps transformer)  non regulated power supply because my amplifiers did not have HV regulated power supply.

But this was a long time ago.  :-DD......something like 1968...1970
« Last Edit: November 20, 2017, 10:12:22 PM by oldway »
 
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Offline b_force

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Re: Looking for yours opinions! HV bench power supply
« Reply #62 on: November 20, 2017, 11:03:00 PM »
The variac option is actually not so bad with a decent MOSFET regulator.
Since a variac is wise to use anyway with these kind of circuits.
"If you can't explain it simply (or at all), you don't understand it well enough." A. Einstein

http://www.oneworldconcepts.com/
 
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Online T3sl4co1l

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Re: Looking for yours opinions! HV bench power supply
« Reply #63 on: November 21, 2017, 12:04:14 AM »
The most common switching supply topology in diy internet is terrible in ripple and emi sence
I`m not experienced in high grade PS and I have no ideas to do it
can You post some links about quiet ps shematics? 300mV ripple voltage at [email protected] will be affordable

The two main problems are poor layout, and lack of filtering.

Layout is critical.  A bad layout can affect the schematic, to the extent that the circuit is incapable of operating as intended (self interference)!  A good layout reduces noise sources in the first place.

Filtering can always be done, and again, layout is important.  Consider the case where all wires entering and exiting a module must pass through a shield: the shield provides a unipotential surface, and each wire passing through the shield must be filtered.  By filtering all wires against a common (unipotential) shield, all unbalanced AC currents can be eliminated.

The same method still applies if you make compromises, like common mode filtering of input and output pairs (which allows you to save on the cost of inductors).  Indeed, this is necessary for mains input, because mains is itself AC, so it can only be filtered so much before it ceases to be mains. :)

Here's an old circuit I made,



You can ignore the other outputs (like 6.3V, 2kV and -250V), and consider just the positive output (250V).  Note the input and output filters.

This exact circuit never worked very well, due to its voltage mode design, and due to excessive recovery losses in the diodes, due in part to a poor transformer design.  But the noise output was well within specification.

I later modified this design (rather aggressively; "modify" is something of a misnomer here, as more than half of the circuit board was replaced :) ) to a flyback type supply, which operates much more safely and efficiently.

Tim
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Offline 001

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Re: Looking for yours opinions! HV bench power supply
« Reply #64 on: November 21, 2017, 01:52:15 AM »
Awesome project  :-+ Thanx!
How large transformers cores I need?
But how to redesign it to 230V mains?
 

Online T3sl4co1l

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Re: Looking for yours opinions! HV bench power supply
« Reply #65 on: November 21, 2017, 02:15:28 AM »
For 200W power levels, something in the EE33 or ETD29 range will do for the power transformer.  Gate drive transformer and filter chokes can be off the shelf parts.  Understand that a switching power supply is a much larger challenge, and will require an oscilloscope to test.

Tim
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Offline oldway

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Re: Looking for yours opinions! HV bench power supply
« Reply #66 on: November 21, 2017, 03:10:16 AM »
Your chance or never to learn why ALWAYS to wear safety glasses when you make experiments with Mosfet, and mostly with TO247....  :-DD
« Last Edit: November 21, 2017, 03:13:03 AM by oldway »
 

Online T3sl4co1l

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Re: Looking for yours opinions! HV bench power supply
« Reply #67 on: November 21, 2017, 03:54:42 AM »
Your chance or never to learn why ALWAYS to wear safety glasses when you make experiments with Mosfet, and mostly with TO247....  :-DD

Good point by the way, whether silicon or vacuum filled.  Solder can splash, sparks can fly, capacitors can explode.  And safety squints aren't going to save you forever. :)

Tim
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Offline 001

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Re: Looking for yours opinions! HV bench power supply
« Reply #68 on: November 21, 2017, 04:49:24 AM »
Solder can splash, sparks can fly, capacitors can explode.

Thanx for clarity but I solder for 48 years yet http://www.eevblog.com/forum/projects/so-old-to-learn-serious-problem/
(but still not understand some engineering :palm: )
 

Offline oldway

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Re: Looking for yours opinions! HV bench power supply
« Reply #69 on: November 21, 2017, 05:18:35 AM »
Whoever has never had a Mosfet that exploded in his face probably never worked on a switching power supply ... And the TO247 really explode violently.

I worked at Cherokee Europe, and I saw a lot of SMPS and I have some MOSFET TO 247 that exploded in my face .....

The schematics you have chosen is not problematic since the transformer driver makes it virtually impossible for both Mosfets to drive at the same time unless .... there is an insulation fault in the driver transformer .... :-DD
That's what happened with me.

In my opinion, the biggest problem is the high stress of the 2 capacitors 0.47µF because of the high rms current.

The control transformer driver, as you have projected, without additional circuit to discharge the gate condensator, is too slow to switch off.
« Last Edit: November 21, 2017, 05:22:19 AM by oldway »
 

Offline chris_leyson

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Re: Looking for yours opinions! HV bench power supply
« Reply #70 on: November 21, 2017, 05:41:12 AM »
Found this the other day https://linearaudio.nl/t-reg-tube-voltage-regulator It's a nice design and the idea is based on the obsolete MC1466L "floating" voltage regulator. The original design used tubes or enhancement mode mosfets, DN2540, and it appeared in the March 2009 edition of Elektor and very recently audioxpress http://www.audioxpress.com/article/t-reg-a-high-voltage-regulator-for-tube-amps. It had a habit of blowing up the enhancement mode mosfets when shorted out but I think the design has been updated for depletion mode mosfets with a much larger SOA. Hmmm... think I've got a spare EL34 somewhere will have to spice it up to see if it's short circuit proof. EDIT: Oops got enhancment and depletion mixed up
« Last Edit: November 21, 2017, 07:20:16 AM by chris_leyson »
 

Online T3sl4co1l

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Re: Looking for yours opinions! HV bench power supply
« Reply #71 on: November 21, 2017, 05:47:13 AM »
Yes, first improvement is using TL598 with schottky clamp diodes to drive the GDT directly -- this gives a proper waveform, with fast fall time.  I think that was actually this, https://www.seventransistorlabs.com/Images/GateDrive1.jpg (though time/div is missing, a shame).  That prevents direct shoot-through, but overheating transistors (due to excessive switching loss and load current) will still fail shorted.

The biggest problem I had was actually diode recovery loss.  Too much LL in the transformer resulted in significant secondary-side overshoot, even with damping resistors and doubled up diodes.  Diodes don't connect in series well, either: if recovery times are not matched, then the first one that recovers sees full voltage, and avalanches, until the other one opens.  Basically, as reverse voltage increases, the diodes continue carrying full load current, until the last diode finishes recovery.  Huge dissipation.  Recovery time goes up with temperature, so it's a runaway situation.

Nowadays, it's easy enough to spend a couple bucks more and plop in a SiC schottky -- recovery loss is eliminated.  (I took this route on the "modified" version, with flyback converter: tried it with UF4007 first, got too hot -- probably as much from conduction loss as recovery, because peak current is much higher in a flyback converter.  Plopped in a C3D04060F, and she runs cool and clean.)

Tim
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Online Hero999

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Re: Looking for yours opinions! HV bench power supply
« Reply #72 on: November 21, 2017, 11:11:43 PM »
R3 would be much better as a CCS, and then TR2 isn't so important (indeed, it can be removed if the minimum load is more than the CCS current -- it might be worth tacking on a second CCS to do just this!).

The LM317 ensures current limiting, though not very appropriate for high voltages -- a low current model (~100mA) would be welcome.  Or, a series output resistor and diode can also be used to pull down ADJ when current draw exceeds a lesser limit, and this will act as quickly as the regulator can.  Downside, output regulation is made poorer.

And of course, a MOSFET version would be better -- but that's a trivial substitution, actually. :)

Tim
I thought the requirement was for a 200mA, yet the LM317L is only rated to 100mA. I suppose a good reason for running the LM317 at a higher voltage differential than 15V, is the safe operating area protection will kick in and limit the current to around 400mA. If that's not low enough, another transistor could be added to cut-off the base drive to Tr1, when the voltage across a sense resistor exceeds its VBE threshold.

Yes using a current source for R3 would be better, at the expense of the additional complexity. Whether it's worth it or not depends on how much variation there is in the input-output differential. It's probably worth keeping Tr2, as this is for a bench power supply, which could be operated with no load. A constant current load could be added to the output, but that's probably more complex than Tr2.

EDIT:
Don't used the attached circuit for such high voltages. It will exceed the safe operating area of the BJT!

Use a MOSFET with a suitable SOA, such as the FQL40N50.
« Last Edit: December 03, 2017, 05:14:35 AM by Hero999 »
 
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Offline oldway

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Re: Solved. Tread to delete. maybe
« Reply #73 on: November 22, 2017, 01:22:32 AM »
What's the matter here? You are crazy... |O |O |O

Is this the first time you take part of a forum ?
You are not alone on earth.....This topic has a lot of informations for who need a HV power supply.....You can't delete all our work.....

Restore the original title of the topic.... :palm:
« Last Edit: November 22, 2017, 01:26:48 AM by oldway »
 
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Offline 001

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Re: Looking for yours opinions! HV bench power supply
« Reply #74 on: November 22, 2017, 03:32:30 AM »
The idea of an hybrid power supply with solid state control and vacuum tube as a series regulator is excellent.

How to substitute V1 V2 V3 with semiconductors in this shematic?
 


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