Utilising the high voltage linear rgeulators

For the three and more legged things
Post Reply
User avatar
Paul Barker
Social Sevices have been notified
Posts: 8867
Joined: Mon May 21, 2007 9:42 pm

#1 Utilising the high voltage linear rgeulators

Post by Paul Barker »

Image

Thinking to use above topology straight off the rectifier. (inserted section learned from the 15mA situation) I see that I would have to change R1 and R2, with R1 at 82ohm for the 15mA and R2 sets up the voltage drop across the tracking preregulator, so I can share some more of the HT across it, and I shall try to set both regulators to 65v quiescent as if line was 240v, then between them they can handle any eventuality, I suppose a double gang pot which in one useage adjusts both chips is ideal but tricky to achieve. Am I making life too difficult?shall I shove a zenner from out of chip two to adj of chip 1?) Thought one of my Black Gates would assist, so put 100uF from rectifier then onto a floating version of above, using the TL783.

I was endered by it because it has a dmos output transistor within it capable of sourcing 700mA but can also handle 125v. I believe it also contains internally the diode from out to in which protects from reverse spikes. (I think I am wrong about this other people seem to add an external diode.) though in the block diagram of the chip is has inetrnal protection block, this diode may not be in it.

I took the 30ms graph (max time they give) of current /voltage tolerance

Image

I presume using a decent heatsink a quiescent current and voltage of the 125 degree line perhaps with a 20% conservative fall back for transients would work? I mean if it isn't capable of that it will just act as a fuse and blow, then I have no B+, and aslong as Black Gate rated sufficiently no other losses but the chip.

So I could pass 100v at 180mA through the second one of these utilised in first schematic topology. I don't think the prior tracking chip shares anything but it's dropout voltage, is that right? So if I wanted to drop more voltage I would have to cascade second stages. OR I could just use our trasitional methods.

Now these will be floating so I plan to assemble then on mini boards stand them above the top plate and cover them with a cage made of the little stationary slotted steel pen holders and such like from Wilkinsons.

Question? How to you float the Adj pin? A Zenner string from true ground?OR large value R1?

OK I now found this schematic. So it seems there isn't an internal diode I better use one. And they use a large resistor for R1. I presume selected for a current. Can someone remind me the desired current for a linear reg adj pin is it 10mA? I see they have sized theirs below for 15mA. right now I read it in the data sheet, when passing 125v across the chip you have to use 15mA minimum on adj to out. So R2 would be notionally 82 ohm in their example. ADJ reference voltage would settle at a figure between 1.2 and 1.3v.

I suppose the wise money consumes most of the stand off ground voltage either with zenners or with a large value resistor, then a variable resistor right at the top, but the 82ohm R2 is fixed. So your desired output voltage can be tuned in. I can see that taking into account line variation of say 230 to 250v I would have to settle the chip at say 65v for a line of 240v so that it will maintain my desired B+ whichever persons house I plug the amp in to. Then If I want further regulation, which I may have room for, I can pop another one in as a current source and design the current for the quiescent voltage of my output valves plus the same amount again through my shunt reg valves. But if I can't fit shunt reg valves with heater supply into this baby I shall just use another series reg, not so much for the regulation, though that would maybe improve on what is already good, but as a voltage drop vehicle.

Image
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
User avatar
ed
retired
Posts: 5384
Joined: Thu Jun 21, 2007 4:01 pm
Location: yorkshire
Contact:

#2

Post by ed »

0-40vac in
-440 +440vdc out ?

?



:scratch:
There's nowhere you can be that isn't where you're meant to be
User avatar
pre65
Amstrad Tower of Power
Posts: 21373
Joined: Wed Aug 22, 2007 11:13 pm
Location: North Essex/Suffolk border.

#3

Post by pre65 »

ed wrote:0-40vac in
-440 +440vdc out ?

?

:scratch:
I read it as -440v and -400v. :santa:
The only thing necessary for the triumph of evil is for good men to do nothing.

Edmund Burke

G-Popz THE easy listening connoisseur. (Philip)
User avatar
ed
retired
Posts: 5384
Joined: Thu Jun 21, 2007 4:01 pm
Location: yorkshire
Contact:

#4

Post by ed »

pre65 wrote:
ed wrote:0-40vac in
-440 +440vdc out ?

?

:scratch:
I read it as -440v and -400v. :santa:
whoops, oh yeah my bad!

Oh curse that chap that sold me the talisker
There's nowhere you can be that isn't where you're meant to be
User avatar
pre65
Amstrad Tower of Power
Posts: 21373
Joined: Wed Aug 22, 2007 11:13 pm
Location: North Essex/Suffolk border.

#5

Post by pre65 »

ed wrote: Oh curse that chap that sold me the talisker
You better have some more before it evaporates. :wink:
The only thing necessary for the triumph of evil is for good men to do nothing.

Edmund Burke

G-Popz THE easy listening connoisseur. (Philip)
User avatar
andrew Ivimey
Social Sevices have been notified
Posts: 8307
Joined: Mon Jun 11, 2007 8:33 am
Location: Bedford

#6

Post by andrew Ivimey »

Still, we know what you mean Paul :-)
Philosophers have only interpreted the world - the point, however, is to change it. No it isn't ... maybe we should leave it alone for a while.
User avatar
Paul Barker
Social Sevices have been notified
Posts: 8867
Joined: Mon May 21, 2007 9:42 pm

#7

Post by Paul Barker »

Minimum current 15mA so useless for loading a VA stage of a 6em7.
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
User avatar
Mike H
Amstrad Tower of Power
Posts: 20157
Joined: Sat Oct 04, 2008 5:38 pm
Location: The Fens
Contact:

#8

Post by Mike H »

You can get that with the ADJ resistor chain, I did a quick calc on the above and if the o/p of that is 40V, it gave me >14mA thru the 2.7k & 82R.

:?:
 
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
User avatar
Mike H
Amstrad Tower of Power
Posts: 20157
Joined: Sat Oct 04, 2008 5:38 pm
Location: The Fens
Contact:

#9

Post by Mike H »

For some reason this has started me thinking about capacitor multipliers Image
 
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
Post Reply