ruffrecords

HT SMPS
« on: November 02, 2019, 05:25:48 PM »
I just took delivery of a SUNYIMA EC42 SMPS transformer:

https://www.aliexpress.com/i/32495030305.html

Because I still think it is worth investigating creating a few 100mA of tube HT from a chunky 12V heater power supply (also SMPS). Then I found this:

https://www.aliexpress.com/item/32969027567.html?spm=a2g0s.9042311.0.0.3da24c4dRb1Pdb

which is basically a kit to build pretty much what I am thinking of. it will need some mods to close the loop but it should be a good basis for experimentation.

Whilst looking around the same site I came across this:

https://www.aliexpress.com/item/32997695785.html?spm=a2g0o.productlist.0.0.3e1f4615NdABLp&algo_pvid=26739ab4-b507-42db-ada0-8d2fd48b55b2&algo_expid=26739ab4-b507-42db-ada0-8d2fd48b55b2-0&btsid=e0c38663-5fcf-48e7-acdc-78c4ed0993f6&ws_ab_test=searchweb0_0,searchweb201602_6,searchweb201603_55

which supposedly takes mains input and provides 265V dc at 150mA and 6.3V dc at 4.5 amps. I think I might buy one just to see how it is done.

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'


scott2000

Re: HT SMPS
« Reply #1 on: November 03, 2019, 03:01:18 AM »
 :o  Interesting!
One of the reviews (2nd one down) said they had an issue with the heater supply not performing up to spec from what I understood.....
Quote

which supposedly takes mains input and provides 265V dc at 150mA and 6.3V dc at 4.5 amps. I think I might buy one just to see how it is done.

« Last Edit: November 03, 2019, 03:16:06 AM by scott2000 »

ruffrecords

Re: HT SMPS
« Reply #2 on: November 03, 2019, 05:29:20 PM »
:o  Interesting!
One of the reviews (2nd one down) said they had an issue with the heater supply not performing up to spec from what I understood.....

That is correct and it is a common issue with switched mode power supplies (rather than a fault with them). The problem is inrush current in cold heaters is several times the nominal value. This means if you put 4 amps of heaters on a 4amp SMPSU it will immediately go into current limiting at turn on because it is being asked for 8 amps or so until the heaters get hot and their resistance drops. Exactly the same happens with current limited linear supplies (I know because it happened to me).

A lot depends on the current limit value. If it is high enough then the heaters will start to warm, their resistance will increase and eventually the power supply will come out of current limit. However, many power supplies (both SMPS and linear) set a very low current limit. I had a reputable linear supply that took nearly 30 seconds to exit current limiting  - fortunately I was able to tweak its current limit so this dropped to 10 seconds.

Many modern SMPS use what is called hiccup mode for current limit. This results in bursts of full current being applied and it will much more reliably exit current limit. Even so, I still rate my heater SMPS at twice the rated current for the tubes.

Bottom line is although this SMPS can output over 4 amps at 6.3V you can only reliably expect it to fire up 2 amps of tube heaters.

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

scott2000

Re: HT SMPS
« Reply #3 on: November 03, 2019, 06:06:31 PM »
Fascinating... Thanks!

Re: HT SMPS
« Reply #4 on: November 03, 2019, 06:30:22 PM »
Quote
and provides 265V dc at 150mA and 6.3V dc at 4.5 amps

What I don't like about all these variants around is that the heater taps aren't conducive to elevation or hum suppression techniques. For dialled in efficient HT though, without big dropping resistors burning; the attraction is great. Followed by a big choke of course!

R

ruffrecords

Re: HT SMPS
« Reply #5 on: November 04, 2019, 03:20:37 AM »
What I don't like about all these variants around is that the heater taps aren't conducive to elevation or hum suppression techniques. For dialled in efficient HT though, without big dropping resistors burning; the attraction is great. Followed by a big choke of course!

R

I am thinking of this primarily for HT. I need getting on for 300mA of really low noise HT for the tube mixer I am building right now. For a linear version I heed some serious RC filtering followed by a regulator. That is some serious iron, PCB real estate and a far bit of heat. A switcher would be much smaller, could be followed by much smaller RC or LC filtering and the regulator would have a fixed input voltage which simplifies thermal design.

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

Re: HT SMPS
« Reply #6 on: November 07, 2019, 06:27:53 PM »
Theres one on ebay I havent spotted before ,

https://www.ebay.com/itm/NEW-500W-0-300V-DC-Output-Adjustable-Switching-Power-Supply-CNC-WITH-CE/172107145711?hash=item281262a1ef:g:zNgAAOxy69JTDg-b

It has a lot more current capacity than you require  and a fan which might not suit either .

 




ruffrecords

Re: HT SMPS
« Reply #7 on: November 08, 2019, 03:31:55 AM »
Theres one on ebay I havent spotted before ,

https://www.ebay.com/itm/NEW-500W-0-300V-DC-Output-Adjustable-Switching-Power-Supply-CNC-WITH-CE/172107145711?hash=item281262a1ef:g:zNgAAOxy69JTDg-b

It has a lot more current capacity than you require  and a fan which might not suit either .

That is a new one. They seem to appear every now and a gain but as you say the power output is much more than we need. I wonder what applications they get used for?


Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

Re: HT SMPS
« Reply #8 on: November 08, 2019, 12:50:19 PM »
You can order this 500w package in a range of voltages all the way  from 12  to 300 v , so it seems  likely they are able to custom wind the switcher transformer  and use applicable components for the voltages/currents  required , the other thing is they claim CE approval, I'm not sure if thats applicable to your build or  not .  Maybe they have some more modestly sized units they can do custom voltages for you on . 




« Last Edit: November 08, 2019, 01:02:45 PM by Tubetec »



ruffrecords

Re: HT SMPS
« Reply #10 on: November 08, 2019, 04:14:11 PM »
It is tempting to buy one just to see how they do it.

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

mjrippe

Re: HT SMPS
« Reply #11 on: November 09, 2019, 03:39:09 AM »
What I don't like about all these variants around is that the heater taps aren't conducive to elevation or hum suppression techniques. For dialled in efficient HT though, without big dropping resistors burning; the attraction is great. Followed by a big choke of course!

R

What hum?  Filaments are 6.3v DC. 

Ian, I am anxiously awaiting your review of these supplies.  So anxious that I may order one myself ;-)

ruffrecords

Re: HT SMPS
« Reply #12 on: November 09, 2019, 12:13:14 PM »

Ian, I am anxiously awaiting your review of these supplies.  So anxious that I may order one myself ;-)
The available HT current from these is much higher than I would ever need. My favourite contender at the moment is the Meanwell one that outputs 300V at up to 500mA. I bought one ages ago and when I get time I plan to add the old FET/zener regulator on the end of it to drop the volts to 250V and get rid of any mush:

https://www.meanwell-web.com/content/files/pdfs/productPdfs/MW/ELG-150-C/ELG-150-C-spec.pdf

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

mjrippe

Re: HT SMPS
« Reply #13 on: November 09, 2019, 06:22:15 PM »
Whilst looking around the same site I came across this:

https://www.aliexpress.com/item/32997695785.html?spm=a2g0o.productlist.0.0.3e1f4615NdABLp&algo_pvid=26739ab4-b507-42db-ada0-8d2fd48b55b2&algo_expid=26739ab4-b507-42db-ada0-8d2fd48b55b2-0&btsid=e0c38663-5fcf-48e7-acdc-78c4ed0993f6&ws_ab_test=searchweb0_0,searchweb201602_6,searchweb201603_55

which supposedly takes mains input and provides 265V dc at 150mA and 6.3V dc at 4.5 amps. I think I might buy one just to see how it is done.

Hi Ian,

I was referring to this one.  Often clients have a couple of old RCA, Langevin, etc tube modules they want racked up.  This is way more than enough for a pair of tube preamps, but it is inexpensive so I wouldn't feel bad "wasting" it on smaller projects.  I'll look around the site for a smaller one though.

Mike

ruffrecords

Re: HT SMPS
« Reply #14 on: November 10, 2019, 03:03:34 AM »
@MIke, OK gotcha. I have already ordered one of those just to see how they do it.

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'


 

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