PRR Vari-mu
- Thread starter MikkelM
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Svart
Well-known member
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?
Edit: Since I am ignorant of tube design, what happens if the 100vdc is higher or lower than dead-on 100vdc?
Svart
Well-known member
is there a link somewhere to this line amp? i can't seem to find it in any of the metas or by searching?? :?:
Svart
Well-known member
i swear that wasn't there!
too many :guinness: :guinness: :guinness: i think.. sorry!
too many :guinness: :guinness: :guinness: i think.. sorry!
Svart
Well-known member
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?
> 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
Adjusts threshold by trimming the level into the sidechain.
http://headfonz.rutgers.edu/comp5/Comp5.html
Svart
Well-known member
Thanks PRR, now that you said that it's as clear as day.. this cold medicine is making me confused!
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:
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:
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.
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.
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
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
The LTR110's should do fine here. Monacor also has a ground isolator transformer named fga40
Jakob E.
Jakob E.
Yes - you could do a similar setup to the Pultec supply..
Jakob E.
Jakob E.
That looks right..
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
Is the 12V output for the heaters ok? I'm guessing I can reduce R10 a lil smidge?
Best,
D
peterc
Well-known member
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
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
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