Hello! I stud in electronic but I am a beginner! I am very interresting by the Zen4 project! I have a question about the power supplie! At home, I have 8 big capasitor! 20 000uF 50 V can I but this capasitor in "parallel" for the recommanded 25 000uF or the 50 v value of the capasitor will be to dangerous? Thank you !!!
You just have to connect them all parallel.Will make your bank of capacitors,assuming the power supply is asymetrical ( ie V+ and ground.)
If you need symmetrical power supply ( ie V+/GND/V-) then you have to get them like this
-C-C-C-C- V+ rail all capacitors + together
GNDGND- Ground (links minus of upper C and plus of
lower C alltogether)
-C-C-C-C- V-rail all capacitors - together
Hope this is clear enough but don't get your hands on it!!!!
Best regards
If you need symmetrical power supply ( ie V+/GND/V-) then you have to get them like this
-C-C-C-C- V+ rail all capacitors + together
GNDGND- Ground (links minus of upper C and plus of
lower C alltogether)
-C-C-C-C- V-rail all capacitors - together
Hope this is clear enough but don't get your hands on it!!!!
Best regards
For the Zen IV you only have V+ and Ground. If you use two of those capacitors in parallel, you will have 50,000 uF of capacitance. Make two amps for stereo, and you will have 4 spare capacitors left over.
For a better supply, use a low-resistance 2mH air-core inductor between the two caps in parallel, giving you C-L-C and a very good power supply. (That's a Pi filter). Do a search for posts by Nelson Pass with the words filter and supply and you should find some good comments by him. (You can't search for "Pi" because the search engine won't take two-letter words)
For a better supply, use a low-resistance 2mH air-core inductor between the two caps in parallel, giving you C-L-C and a very good power supply. (That's a Pi filter). Do a search for posts by Nelson Pass with the words filter and supply and you should find some good comments by him. (You can't search for "Pi" because the search engine won't take two-letter words)
I recommand air core,no saturation at high currents
The diameter of the wire must be as big as possible,
of course,to handle current.
A goog value is 2,7mH.DC resistance must be low.
The best way to do is take a big inductor for speaker crossover.Some are rated 300W.For hi-fi,perhaps.
But for a power supply,let's bet it doesn't hold more
than 25W continious DC.
With an air core inductor of 2,7mH and a wire diameter
of 1,4mm,let's say it's OK for the purpose
Hope this helps
The diameter of the wire must be as big as possible,
of course,to handle current.
A goog value is 2,7mH.DC resistance must be low.
The best way to do is take a big inductor for speaker crossover.Some are rated 300W.For hi-fi,perhaps.
But for a power supply,let's bet it doesn't hold more
than 25W continious DC.
With an air core inductor of 2,7mH and a wire diameter
of 1,4mm,let's say it's OK for the purpose
Hope this helps
Here are a few of the threads in which Mr. Pass makes mention of the Pi filter I suggested. I should tell you that I don't have lots of experience, but I built a Zen IV and used a filter like this with C-L-C of 30,000uF, 2mH, 60,000uF and it works well. The inductor is 14Ga. wire (with a search you can convert from "AWG" wire gauge to mm). It's resistance is low so that it generates no heat, so I think the wire size is sufficient.
http://www.diyaudio.com/forums/show...247&highlight=filter+supply+inductor#post9247
http://www.diyaudio.com/forums/show...784&highlight=filter+supply+inductor#post7784
http://www.diyaudio.com/forums/showthread.php?s=&postid=13061&highlight=Erse#post13061
And... one more quote from Mr. Pass:
"For pi filter, something 1 mH or larger; I usually use
2 to 4 mH, and the value is not at all critical. On the
caps, I use lots of capacitance, usually distributed
equally on either side of the inductor. Again, this is
not critical."
So I would suggest that you not worry. Build your amp; maybe not in its final cabinet at first. If you don't have the inductors, don't use them. Listen and see if you like it! If you hear some noise from the power supply and you want to make it quieter, then find some inductors.
The ones that I got were from the first series on this page, 2.00mH, .306 ohms DC resistance. http://www.zalytron.com/erse.htm
http://www.diyaudio.com/forums/show...247&highlight=filter+supply+inductor#post9247
http://www.diyaudio.com/forums/show...784&highlight=filter+supply+inductor#post7784
http://www.diyaudio.com/forums/showthread.php?s=&postid=13061&highlight=Erse#post13061
And... one more quote from Mr. Pass:
"For pi filter, something 1 mH or larger; I usually use
2 to 4 mH, and the value is not at all critical. On the
caps, I use lots of capacitance, usually distributed
equally on either side of the inductor. Again, this is
not critical."
So I would suggest that you not worry. Build your amp; maybe not in its final cabinet at first. If you don't have the inductors, don't use them. Listen and see if you like it! If you hear some noise from the power supply and you want to make it quieter, then find some inductors.
The ones that I got were from the first series on this page, 2.00mH, .306 ohms DC resistance. http://www.zalytron.com/erse.htm
Most caps are rated for surges at least 15% over the specified voltage. Your concern is if your transformer develops a short you could get 120VAC through the secondaries. Not good. If your going to run the voltage up close to the caps rating, you should put a properly rated fuse on the secondary before the cap bank. I recommend a slow blow fuse because the larger cap banks will blow a normal fuse when you turn the amp on and the caps suck up a surge of current charging up. Another concern is the age of the capacitors. If they are old then you should be more careful as the dielectrics break down with age as well as use.
With 18 VAC out the secondaries you should get about 25VDC after rectification and about 23-24VDC after the caps any other passives you put into your filter section. This should be well within the limit of those caps. While old, they are probably ok unless they have heavily used before. If you know someone with a quality cap tester test them for leakage if you really want to be sure of their integrity.
Let's give this some thought.
arold19,
I am assuming that you are intending to build a dual-mono version of the Zen V4. If that is the case and you desire to follow Mr. Pass' design, I would also assume that you intend to utilize your transformers with secondaries in series. After forward junction drops and other possible "parasitics" you're left with approximately 50 V. This is the maximum working voltage on your capacitors which are 27 years old. Unfortunately, I am not as optimistic as Philo, and would highly recommend that you err on the side of caution and heed Philo's sagely advice.
If you are interested in the Pi filter concept, by all means have a go at it. I believe that the link to the actual inductor used by Mr. Pass is given below. It was produced by Erse. And if I am not corrected I belive it was an iron core inductor--which has it's own benefits as well as drawbacks. This inductor is available from several different companies. I just purchased a few from Parts Express to use in various projects. It should be noted that the Zen V4, already has built into its design regulation that effectively does what the Pi filter was designed to do in Zen V2.
I would also make the argument that with the Pi filter AND **excessive capacitance** there would be the possibilitiy for high-frequency noise to appear on the voltage rails which could possibly cause unwanted audible artifacts due to the short diode conduction angle. In the capacitor thread, Mr. Pass and Jan Didden both make excellent comments concerning biasing effects on conduction angles based on capacitance values. Please read.
Check out these links:
How big do the capacitors have to be?
Power supply inductors (what specs?)
Later,
arold19,
I am assuming that you are intending to build a dual-mono version of the Zen V4. If that is the case and you desire to follow Mr. Pass' design, I would also assume that you intend to utilize your transformers with secondaries in series. After forward junction drops and other possible "parasitics" you're left with approximately 50 V. This is the maximum working voltage on your capacitors which are 27 years old. Unfortunately, I am not as optimistic as Philo, and would highly recommend that you err on the side of caution and heed Philo's sagely advice.
If you are interested in the Pi filter concept, by all means have a go at it. I believe that the link to the actual inductor used by Mr. Pass is given below. It was produced by Erse. And if I am not corrected I belive it was an iron core inductor--which has it's own benefits as well as drawbacks. This inductor is available from several different companies. I just purchased a few from Parts Express to use in various projects. It should be noted that the Zen V4, already has built into its design regulation that effectively does what the Pi filter was designed to do in Zen V2.
I would also make the argument that with the Pi filter AND **excessive capacitance** there would be the possibilitiy for high-frequency noise to appear on the voltage rails which could possibly cause unwanted audible artifacts due to the short diode conduction angle. In the capacitor thread, Mr. Pass and Jan Didden both make excellent comments concerning biasing effects on conduction angles based on capacitance values. Please read.
Check out these links:
How big do the capacitors have to be?
Power supply inductors (what specs?)
Later,
Todd,
I have been neck deep both a gainclone and getting my aleph X parts together that I forgot the Zen is only V+ and ground. Thanks for the QA check.
Arold, with your transformer wired in series (no center tap to ground) you are really pushing the limits of those cap's capabilities. I would try and get different capacitors. It just isn't worth risking personal injury and the other components in your amp (ie. the PCBs) just to save some money on caps. Take some time and check ebay or surplus electronic stores for something better suited (and newer!). If I recall, Nelson only really recommends @25KuF/chan in his article, calling the law of diminishing returns and reiterating the point behind the Zen is minimalism.
I have been neck deep both a gainclone and getting my aleph X parts together that I forgot the Zen is only V+ and ground. Thanks for the QA check.
Arold, with your transformer wired in series (no center tap to ground) you are really pushing the limits of those cap's capabilities. I would try and get different capacitors. It just isn't worth risking personal injury and the other components in your amp (ie. the PCBs) just to save some money on caps. Take some time and check ebay or surplus electronic stores for something better suited (and newer!). If I recall, Nelson only really recommends @25KuF/chan in his article, calling the law of diminishing returns and reiterating the point behind the Zen is minimalism.
Thank you very much!
I will try to get other capasitor!
It is boring because a have 8 of those caps, they are very big but now, I know that it is better to don't use it!
In fact, I will make a pi filter with my 1,8mH inductor 18awg! But, before to know that, I was thinking to make a pi filter lake that: C-C-L-C-C But now, I don't think I will buy 8 capasitor! Can I do a filter lake that: C-L-C ???
I will try to get other capasitor!
It is boring because a have 8 of those caps, they are very big but now, I know that it is better to don't use it!
In fact, I will make a pi filter with my 1,8mH inductor 18awg! But, before to know that, I was thinking to make a pi filter lake that: C-C-L-C-C But now, I don't think I will buy 8 capasitor! Can I do a filter lake that: C-L-C ???
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