Ethan

PRR Vari-mu
« Reply #20 on: December 23, 2004, 05:26:29 PM »
Wasn't there talk a while back of modding this to drive well enough for +4 operation?  Does anyone recall the topic?  Or am I imagining things...
I am just the Web Geek here.


Svart

PRR Vari-mu
« Reply #21 on: December 23, 2004, 05:50:11 PM »
there was a topic but it just suggested using another opamp gain stage, I'm going to work on this when i get a chance.  I need(would like) +4 because all my interfaces are +4.  any suggestions from Herr Professor? I was thinking another stage with a simple opa2604 or something with a pot in front of it..?

Edit: Since I am ignorant of tube design, what happens if the 100vdc is higher or lower than dead-on 100vdc?
Welcome to the GroupDIY leper colony! when something falls off, we just replace it with a tube!
occupation: General Electron Mayhem

Alesis X2 information repository:
http://www.theopiumdenproductions.

PRR

PRR Vari-mu
« Reply #22 on: December 23, 2004, 05:54:35 PM »
> what happens if the 100vdc is higher or lower than dead-on 100vdc?

The threshold level changes. That's why there is a trimmer for that.

Ethan

PRR Vari-mu
« Reply #23 on: December 23, 2004, 06:00:54 PM »
I've been thinking of breadboarding NYD's line amp, but haven't really decided what I would use it for.  Perhaps as an amp to this?  Thoughts/Guidance/"you're an idiot" comments always appreciated.
I am just the Web Geek here.

Svart

PRR Vari-mu
« Reply #24 on: December 23, 2004, 06:36:52 PM »
is there a link somewhere to this line amp? i can't seem to find it in any of the metas or by searching?? :?:
Welcome to the GroupDIY leper colony! when something falls off, we just replace it with a tube!
occupation: General Electron Mayhem

Alesis X2 information repository:
http://www.theopiumdenproductions.

Svart

PRR Vari-mu
« Reply #25 on: December 24, 2004, 12:12:18 AM »
i swear that wasn't there!

too many  :guinness:  :guinness:  :guinness:  i think.. sorry!
Welcome to the GroupDIY leper colony! when something falls off, we just replace it with a tube!
occupation: General Electron Mayhem

Alesis X2 information repository:
http://www.theopiumdenproductions.

Svart

PRR Vari-mu
« Reply #26 on: December 28, 2004, 01:22:49 PM »
forgive my ignorance but I am unlcear as to the reason for the 1k trimmer on the output.. is that for impedence or for output attentuation?
Welcome to the GroupDIY leper colony! when something falls off, we just replace it with a tube!
occupation: General Electron Mayhem

Alesis X2 information repository:
http://www.theopiumdenproductions.

PRR

PRR Vari-mu
« Reply #27 on: December 28, 2004, 04:49:04 PM »
> I am unlcear as to the reason for the 1k trimmer on the output.. is that for impedence or for output attentuation?

Adjusts threshold by trimming the level into the sidechain.

http://headfonz.rutgers.edu/comp5/Comp5.html

Svart

PRR Vari-mu
« Reply #28 on: December 28, 2004, 05:26:12 PM »
Thanks PRR, now that you said that it's as clear as day..  this cold medicine is making me confused!
Welcome to the GroupDIY leper colony! when something falls off, we just replace it with a tube!
occupation: General Electron Mayhem

Alesis X2 information repository:
http://www.theopiumdenproductions.

daArry

PRR Vari-mu
« Reply #29 on: January 05, 2005, 07:58:15 AM »
Hey...

Just been going through the mainline site for a misc order of parts and came across a cpl of v cheap transformers which I'm wondering if could be used in this project:

http://www.mainlinegroup.co.uk/mless/main.php?act=Card&id_element=2645

http://www.mainlinegroup.co.uk/mless/main.php?act=Card&id_element=1335

No idea if they're suitable - but this diy lark is a funny game, and u (or i rather) just never know ;)

All the best

 :thumb:


gyraf

PRR Vari-mu
« Reply #30 on: January 05, 2005, 08:11:47 AM »
It's impossible to say from those (missing) specs.

I don't think they'd be useable - but there may be a small chance anyway..

But at the low price of "ground isolation" transformers for car-fi, there should be no reason to try unknown transformers..

Jakob E.
..note to self: don't let Harman run your company..

daArry

PRR Vari-mu
« Reply #31 on: January 05, 2005, 09:53:51 AM »
Cheers jakob...

Have u a specifc part # to hand that I can find in the UK, there's alot of types for those "ground isolation" transformers it seems and I aint to sure...or, I have some monacor LTR110's (4 in all) so I guess I could just use them...?

Also, I'm wondering what to do for a psu - the one PRR has on the page he put up is for 120V US mains...could I make somthing similar to the psu you done for the pultec clone but make some alterations - So, (TX1) 220V:12V > (TX2)12V:120V (then use the same ckt PRR done from that point onwards). Then for the +/- 16V and 12V heater supply just use another 12-0-12V TX...or just take the 2 12VAC lines from between tx1 and tx2 and feed of from there?

Cheers

gyraf

PRR Vari-mu
« Reply #32 on: January 05, 2005, 09:56:57 AM »
The LTR110's should do fine here. Monacor also has a ground isolator transformer named fga40

Jakob E.
..note to self: don't let Harman run your company..

daArry

PRR Vari-mu
« Reply #33 on: January 05, 2005, 10:01:45 AM »
ok - but i aint gonna get far without a psu  :roll:

gyraf

PRR Vari-mu
« Reply #34 on: January 05, 2005, 10:04:44 AM »
Yes - you could do a similar setup to the Pultec supply..

Jakob E.
..note to self: don't let Harman run your company..

daArry

PRR Vari-mu
« Reply #35 on: January 05, 2005, 11:36:23 AM »
like so?:



ta

gyraf

PRR Vari-mu
« Reply #36 on: January 05, 2005, 02:01:40 PM »
That looks right..
..note to self: don't let Harman run your company..

daArry

PRR Vari-mu
« Reply #37 on: January 06, 2005, 07:56:17 PM »
soz to bother again, but i've redrawn another psu ckt based around a dif tx setup as i've a pair of the ones shown to-hand and would like to use them if poss instead of gettin another 2...so, as they are dual type with 15V secondaries (instead of the 12V like before) - would this work?:



Is the 12V output for the heaters ok? I'm guessing I can reduce R10 a lil smidge?

Best,

D

daArry

PRR Vari-mu
« Reply #38 on: January 07, 2005, 10:28:41 AM »
bump...

so...i guess i'll just build the above and turn on from a distance with a snooker cue or summin...lemme see those fingers!

peterc

PRR Vari-mu
« Reply #39 on: January 07, 2005, 02:20:07 PM »
Hi Dearry

For the 100v supply, why not adapt the G9 HT supply & recalculate the resistors to give you 100v regulated.

I've had problems with Zener regulated supplies like this, getting the current right, etc. A pass transistor would help a lot in this situation.

Have a look at this for an example of a zener + pass transistor design.
http://www.welbornelabs.com/pdf.htm

Corrected link :

http://www.welbornelabs.com/ps3.pdf

Regards
Peter
If opportunity doesn't knock, build a door.


 

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