Mpp - Page 439 - diyAudio
Go Back   Home > Forums > Source & Line > Analogue Source

Analogue Source Turntables, Tonearms, Cartridges, Phono Stages, Tuners, Tape Recorders, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 14th January 2012, 01:09 PM   #4381
FdW is offline FdW  Netherlands
diyAudio Member
 
FdW's Avatar
 
Join Date: Feb 2009
Location: Both feet on the ground (near Gouda)
Quote:
Originally Posted by Joachim Gerhard View Post
I use UF4004 diodes.
Good choice, a somewhat less benign version of the 1N4004 I would say, same voltages and currents (over the whole range of diodes).
UF4002 Fairchild Semiconductor Rectifiers
  Reply With Quote
Old 14th January 2012, 01:10 PM   #4382
diyAudio Member
 
Holger Barske's Avatar
 
Join Date: Jan 2001
Location: Ruhrgebiet
Quote:
3N255
Correct me if I am wrong, but this seems to be a very average low cost part. No Schottky barriers, no high speed, no soft recovery.
__________________
Best regards: Holger
www.holgerbarske.com - Deutschsprachiges Paradise-Support-Forum
  Reply With Quote
Old 14th January 2012, 01:13 PM   #4383
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
This are the diodes i use ..
UF 4004 - Ultraschnelle Gleichrichterdiode, DO41, 400V, 1A - 1N.. - UF.. - AA.. Dioden bei reichelt elektronik
Why not build something and look with a scope what happens ?
  Reply With Quote
Old 14th January 2012, 01:14 PM   #4384
FdW is offline FdW  Netherlands
diyAudio Member
 
FdW's Avatar
 
Join Date: Feb 2009
Location: Both feet on the ground (near Gouda)
Quote:
Originally Posted by MRupp View Post
I took the Hagerman paper to be correct but I can't prove if he is right or wrong. And yes, there are many examples whith low resistance values floating around on the WEB, though I do get the impression that this is just a chain of copies. There was a paper on snubbing shottky diodes (possibly from IRF, can't find it right now) that showed what happens if the resistor value is (much) too low, namely that the RC snubber acted like a pure capacitor and would not snub. The best way to find out off course is to measure the live circuit and see the effect of different resister values on the turn off spikes, this way you can tune the value to it's optimum. I am not sure if anyone wants to go to that lenght. I once looked at turnon spikes in a supply by placing a simple pickup coil (air coil from crossover connected to a scope probe, but there may be better ways) and I could clearly see the spikes, though I did not play with snubber values (I was checking the effect of a small C in front of a LC input filter and found some hefty resonances).
Two things, my information is (was not) WEB based, and secondly I did change my insight (opinion) and changed the resistor value to 100 Ohms. The question is would you (and [all] others) agree to these values?

Regards,
Frans.

P.s.
[All] I am now wondering (if ever) all could agree to one idea

Last edited by FdW; 14th January 2012 at 01:19 PM.
  Reply With Quote
Old 14th January 2012, 01:18 PM   #4385
FdW is offline FdW  Netherlands
diyAudio Member
 
FdW's Avatar
 
Join Date: Feb 2009
Location: Both feet on the ground (near Gouda)
Quote:
Originally Posted by Holger Barske View Post
Correct me if I am wrong, but this seems to be a very average low cost part. No Schottky barriers, no high speed, no soft recovery.
Yes it is, and still it will do. But I think the actual part (in first selection) will be something like the UF4004 (as proposed by Joachim). And having a PCB that accepts 'single' diode devices will give us plenty of room to experiment with other devices.
  Reply With Quote
Old 14th January 2012, 01:24 PM   #4386
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
Concerning PSU i would say no !
Some have religious believe in a certain topology, other use certain components ( mostly big and clumsy ) , other claim that an LM317, 337 combo is just fine.
I can only repeat that the Paradise has excellent PSU rejection to begin with. Then Frans made a really good regulator that is already proven in the lab to be very low noise and then we have the pre-regulator external so everybody can try what he thinks is best. Hesener even made provision that the on board shunts can be disabled.
I have measured inside PSUs and especially around the bridges there is more going on then some will think. We really have to build this, make it work and then look if we can fine tune.
  Reply With Quote
Old 14th January 2012, 01:27 PM   #4387
MRupp is offline MRupp  Germany
diyAudio Member
 
MRupp's Avatar
 
Join Date: Dec 2003
Location: Frankfurt area
Quote:
Originally Posted by FdW View Post
Two things, my information is (was not) WEB based, and secondly I did change my insight (opinion) and changed the resistor value to 100 Ohms. The question is would you (and [all] others) agree to these values
Wait a minute, now if I am wrong it will be all my fault Better have the rest of the gang decide for this and not me. I would say though that you can still change resistors afterwards, they cost only a few pennies, so not a big deal.
__________________
Martin Rupp
  Reply With Quote
Old 14th January 2012, 01:32 PM   #4388
FdW is offline FdW  Netherlands
diyAudio Member
 
FdW's Avatar
 
Join Date: Feb 2009
Location: Both feet on the ground (near Gouda)
Quote:
Originally Posted by MRupp View Post
Wait a minute, now if I am wrong it will be all my fault Better have the rest of the gang decide for this and not me. I would say though that you can still change resistors afterwards, they cost only a few pennies, so not a big deal.
Maybe I was not clear about this, but that was my intention, and that is why I added the p.s.

Quote:
[All] I am now wondering (if ever) all could agree to one idea
  Reply With Quote
Old 14th January 2012, 01:33 PM   #4389
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
I see the snubber that way :
R x C create a time constant. If you rase R, C has to go down in value or you get a rather low time constant that may not be effective any more at the high frequency switching spike of the diode. Making R high reduces the damping of the snubber though so a compromise has to be found. I would say the lowest R that works.
I usually use no snubber at all and it works with the UF4004. A C alone without resistor will not work well i think.
  Reply With Quote
Old 14th January 2012, 01:43 PM   #4390
FdW is offline FdW  Netherlands
diyAudio Member
 
FdW's Avatar
 
Join Date: Feb 2009
Location: Both feet on the ground (near Gouda)
Quote:
Originally Posted by Joachim Gerhard View Post
I see the snubber that way :
R x C create a time constant. If you rase R, C has to go down in value or you get a rather low time constant that may not be effective any more at the high frequency switching spike of the diode. Making R high reduces the damping of the snubber though so a compromise has to be found. I would say the lowest R that works.
I usually use no snubber at all and it works with the UF4004. A C alone without resistor will not work well i think.
Most information that I have relates the value of R to the amount of energy that needs to be dissipated (Motorola, National and Rifa). In a way that leaves the C as the variable/value to calculate, but I cannot find information on how to calculate the value of R, other than the formulas found in the Hagener document.

I do agree with Joachim about the need to experiment and measure. Using 100 Ohm and 100 nF seems like a good starting point. It is in accordance with values that are found in National and Rifa papers and (the value for R at the least) agrees with Hagener's paper.

The National information that I have suggests that using a C only will suffice; it goes on to say that the power (of the energy to dissipate) will then be dissipated in the internal resistance of the capacitor, diode and the wiring. (this is for small (like ours) power supplies).

The literal text is “Capacitor shunt on the rectifier diode. Transient power is thus dissipated in the circuit series resistance”.

Last edited by FdW; 14th January 2012 at 01:50 PM.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



New To Site? Need Help?

All times are GMT. The time now is 11:59 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2