Chip Amp PSU Question - diyAudio
Go Back   Home > Forums > Amplifiers > Chip Amps

Chip Amps Amplifiers based on integrated circuits

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 15th June 2005, 03:57 AM   #1
diyAudio Member
 
Join Date: Mar 2005
Location: ddd
Send a message via AIM to Lyerigolfin Send a message via MSN to Lyerigolfin Send a message via Yahoo to Lyerigolfin
Unhappy Chip Amp PSU Question

I've assembled the power supply in this thread:
The (high-cap.) unregulated PSU for chipamps

also the same (basic) design can be found here:
http://www.tnt-audio.com/clinica/ssps1_e.html

and here:
www.zero-distortion.com (ps design section)

My question is about the 0v line. I actually measured this line compared to the earth ground and there was about a 32V-P sine wave showing up. The positive and negative rails displayed proper values when compared to the 0v line.

All of the power supply schematics that I've seen show this 0v rail tied to earth. Last time I checked a 32V sine wave shorted to earth would make quite a few (rather expensive) things blow up.

I could see maybe, if you used two transformers with series windings and tied each of their centers to the 0v point, but is this kind of power supply design possible with only 1 transformer?
  Reply With Quote
Old 15th June 2005, 04:41 PM   #2
diyAudio Member
 
Join Date: Nov 2003
Location: NW Washington
Send a message via MSN to officeboy
This is one of those times when a picture is worth a 1000 words.

Or if a picture is not available, a drawing of the exact items used and how they are hooked up (a schematic, but not a copy of one from the links you posted),.

Also there is a power supply forum that is fairly active and would be able to provide you with some answers.
  Reply With Quote
Old 15th June 2005, 07:53 PM   #3
diyAudio Member
 
leadbelly's Avatar
 
Join Date: Dec 2002
Location: Calgary, Alberta
Default Re: Chip Amp PSU Question

If I understand you correctly, you have built the PS per the schematic with the exception that you did not tie one output of each bridge to ground. This is the line labelled as GND in the carlosfm schematic and you are calling the "0V" line (BTW, it can't be 0V if it's not grounded )

If you have indeed done this and you have no galvanic connection to ground anywhere in your PS circuit on the secondary side of the transformers, then there is nothing wrong. Of course you will read an unusual value like 32V on the "0V", there is nothing in your circuit to reference it to ground.
__________________
Aerodynamics are for people who can't build engines. Enzo Ferrari
  Reply With Quote
Old 15th June 2005, 11:21 PM   #4
diyAudio Member
 
Join Date: Mar 2005
Location: ddd
Send a message via AIM to Lyerigolfin Send a message via MSN to Lyerigolfin Send a message via Yahoo to Lyerigolfin
First off I apologize for not posting this in the PS design forum, I didn't know about it when I created the thread.

Secondly, you are correct. I have assembled the supply with jumper wires and alligator leads without connecting the 0v reference line to ground. To be safe, I decided to measure the voltage from this line to ground before hooking it up, when I did I found the aforementioned voltage. Why exactly will this not just cause a massive failure/fire/catastrophe when shorting this 32V AC to ground? I fail to see how (massive) current wouldn't flow between 32V AC and earth ground.
  Reply With Quote
Old 15th June 2005, 11:21 PM   #5
diyAudio Member
 
Join Date: Mar 2005
Location: ddd
Send a message via AIM to Lyerigolfin Send a message via MSN to Lyerigolfin Send a message via Yahoo to Lyerigolfin
Here's an attached picture of the exact layout that I've built.
Attached Images
File Type: gif ps layout.gif (16.9 KB, 338 views)
  Reply With Quote
Old 15th June 2005, 11:32 PM   #6
diyAudio Member
 
leadbelly's Avatar
 
Join Date: Dec 2002
Location: Calgary, Alberta
Quote:
Originally posted by Lyerigolfin
Why exactly will this not just cause a massive failure/fire/catastrophe when shorting this 32V AC to ground? I fail to see how (massive) current wouldn't flow between 32V AC and earth ground.
Well, what can I say other than read up on some theory? Since you are sitting there at a standstill because you won't take my word for it, at least try shorting "0V" to ground with a fuse so you can move forward and build your amp
__________________
Aerodynamics are for people who can't build engines. Enzo Ferrari
  Reply With Quote
Old 16th June 2005, 12:46 AM   #7
paulb is offline paulb  Canada
diyAudio Member
 
Join Date: Jun 2001
Location: Calgary
Quote:
Originally posted by Lyerigolfin
Why exactly will this not just cause a massive failure/fire/catastrophe when shorting this 32V AC to ground? I fail to see how (massive) current wouldn't flow between 32V AC and earth ground.
You're getting some leakage through various things. It will be a high impedance source. Try connecting a 1K (or whatever) ohm resistor across your meter and then measure the voltage. If it doesn't drop to a very low value, then you've got some serious problem.
  Reply With Quote
Old 16th June 2005, 01:50 AM   #8
diyAudio Member
 
Join Date: Mar 2005
Location: ddd
Send a message via AIM to Lyerigolfin Send a message via MSN to Lyerigolfin Send a message via Yahoo to Lyerigolfin
Quote:
Originally posted by leadbelly


Well, what can I say other than read up on some theory? Since you are sitting there at a standstill because you won't take my word for it, at least try shorting "0V" to ground with a fuse so you can move forward and build your amp
I do plan on taking your word, and everybody elses word for that matter. My workspace is at my uncle's house which I don't go to very often so I don't get to work on it a lot (meaning I sit around and think about it a lot).

The high impedance source makes sense to me. I'll take some current measurements as well as voltage measurements from this return line. I also now realize where the 60hz hum comes from in ground loops, I never found a fully technical enough answer outside of "don't ground this here, because it will form a loop" to completely understand it. I always understood the physical resistance property, but I never knew why it would hum at 60hz.

Thanks for the help.
  Reply With Quote
Old 16th June 2005, 09:10 PM   #9
diyAudio Member
 
Join Date: Nov 2003
Location: NW Washington
Send a message via MSN to officeboy
Just to chip in since I did earlier. Leadbelly is right, you just need a reference point to tie that ground back to. Unless you have a failed transformer or other component.
  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


Similar Threads
Thread Thread Starter Forum Replies Last Post
PT2350 chip question Dxvideo Chip Amps 10 31st December 2009 07:15 AM
Question on DA chip Assyst1606 Digital Source 2 20th January 2009 11:54 PM
IRFZ44N Chip Question? Itsme Car Audio 12 29th October 2007 07:58 PM
Non Isolated Chip Question Adam M. Chip Amps 4 16th February 2004 12:37 AM
Question about chip packages soundNERD Chip Amps 1 2nd January 2004 12:58 PM


New To Site? Need Help?

All times are GMT. The time now is 11:41 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