Jump to content

goldenreference low voltage power supply


kevin gilmore
 Share

Recommended Posts

I'm happy to report that the goldenreference low voltage dual

power supply works as designed, and tests less than 1 microvolt

of noise. Going to have to take it to work and put it in a screen

room to really measure the noise.

 

http://gilmore.chem.northwestern.edu/goldenreferencedual.jpg

 

however there is one silkscreen error seen by the extra + near the

47uf cap on the right side. I will update the files shortly.

 

All 4 of the 47uf caps need to have their plus sides pointing to the left.

 

very happy with this

Edited by kevin gilmore
Link to comment
Share on other sites

thanks for doing this as always, definitely putting these into the preamp

 

between this and the SiC psu's the lt1021 purchases are going to break the bank

 

How much current are those mjw21194 good for without heatsinking? I'm looking up some of the to247 sheets but I don't see the relevant numbers

Link to comment
Share on other sites

my unreg primary is 41v, so its way higher than normal.

 

I did attach the biggest  U bracket heatsinks I had around

(bhse ones)

 

Ran 500ma load.

 

Definitely gets too hot to touch in a few minutes.

 

you do realize this is set for +/-20, so if you want other

voltages you have to change the feedback resistors.

 

(+/-20 is my favorite voltage for ssdynalobal)

Edited by kevin gilmore
Link to comment
Share on other sites

2 watt transformer... no

22 watt, just barely

30 watt transformer is about right

one of the mounting holes is 25th off of square.

current posted boards (dual and singles) have the mounting

holes one size smaller, the silk screen fixed, and 1 resistor

each moved by 25th.

done

measurements this morning in a screen room is about 800picovolts

of noise. and voltage stability exceeding 6.5 digit meter.

anything better is going to require stupidly expensive test gear.

Link to comment
Share on other sites

what's the unpopulated 10 ohm spot for?

it's an error, not connected to anything.

Got mine done and running.

A few things missed in BOM:

512-KSP42TA    4
512-KSP92BU   4
512-1N914         4
821-1N4007       2

 

eUoj792.jpg

  • Like 1
Link to comment
Share on other sites

 

what's the unpopulated 10 ohm spot for?

 

I asked Kevin the same question when inspecting the board. Here is Kevin's response: 

 

"the 10 ohm thing is the krell way of earth ground to power supply ground.

 

very few if any will ever use it. but its there just in case."

 

 

Nice build IKong. 

 

What voltage and current do you have running with the PS and what's the temperature of the MJW21193?

Edited by mwl168
Link to comment
Share on other sites

does that apply to the dual made of two singles in series, or only to the dual made of complementary parts?

 

if you do the 2 complementary singles, then yes, otherwise no.

 

also the bom lists the on board pass transistors, not the off board ones

 

I did more testing, and at 500ma, the minimum dropout voltage seems

to be closer to 3v.  But at 5v, the pass transistors do just fine with a small

heatsink as is.

 

5V, 500ma ...  2.5 watts

Edited by kevin gilmore
Link to comment
Share on other sites

ground down the middle.

there is actually a benefit of dual supplies. the noise spikes what little of them exist

cancel.

Can you provide a bit more information on those noise spikes you see?

 

Also

 

 

measurements this morning in a screen room is about 800picovolts

of noise. and voltage stability exceeding 6.5 digit meter.

under which circumstances, bandwidth and current pulled for instance ?

Can you provide some comparison to the standard LV 78/7915 type supply?

 

 

To sum up:

- the GR LV can regulate at 3V but would be better at 4-5V,? and can be used up to 60V depending on components used?

- the GR HV can regulate at 8V?

Link to comment
Share on other sites

the noise spikes are 120hz (100hz for you) and due completely to the switching noise
of the input diodes. every power supply, even tube rectified ones do this. The idea
is to remove the spike noise, and its not easy. caps across the diodes, etc, just does not
work.

and by the way, so far, I can't even get close to these numbers with a shunt regulated
supply, the noise rips right thru the main current source.

7815 is rated at 90 microvolts of noise (ti datasheet). which is great except that in the typical configuration
the diode noise rips right thru, and is usually in the millivolt range. and the voltage stability
is +/-4% over commercial temperature range. plus line and load regulation.

S22, same thing, the capacitance multiplier at the input is useless. Some companies in
the stupidly overpriced 3 terminal replacement business call this a gyrator. Nope, not a gyrator.

yes it can regulate at 3V, but you don't want to do that. What you might want to do is use
that voltage to calculate line voltage -15% for the absolute minimum voltage. Then make
sure all the components are rated for line voltage +15%

its all about heat in the pass transistors.

if you want to go down to 8 volts, you have to change the series zener to 4.7v
that zener is there to make sure the thing starts up under load.
and change the reference to 5v

 

here is the original design that was modified by ucc, then modified by me.

http://waltjung.org/PDFs/Improved_PN_Regs.pdf

Edited by kevin gilmore
  • Like 1
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...