grounding & power supply questions - 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 January 2004, 01:52 PM   #1
diyAudio Member
 
Join Date: Mar 2003
Location: austin, tx
Default grounding & power supply questions

I have a gainclone that I built following the model on the Decibel Dungeon pages (a modified version of a design proposed by Thorsten Loetch). It has been running for about half a year now, and I just put it into a more refined case. It is my first attempt at DIY amps and have learned a bit, although my lack of electronic knowledge is still apparent. Nonetheless, my first attempt has been a success and am very happy with the results. I did notice a couple of things in doing this switch that I'm curious about and would like resolved.

1. I have a 20-0-20 transformer for each chip. The "20" connections go to the bridge rectifier. The GC schematics have no indication (as far as I know) of where the "0v" (ground?) connects into the circuit, if at all. I had it connected to the power star ground and everything worked fine. Upon switching cases, I thought that perhaps "0v" was not necessary to be connected to the circuit, but the amp sounded like crap and faded to nothing in a couple of seconds. I reconnected it to PSG and it worked again. I moved the "0v" connection in the circuit to the ground directly at the AC power inlet, and can tell no difference in sound. Where should the "0v" connection from the transformer go?

2. When the transformer is connected to the bridge rectifier but not the chip, I get roughly +-20v at the rails, but when I have the chip attached and the "0v" connection on the transformer connected to the circuit as mentioned above, I get +-27v at the rails. disconnect the "0v" and leave the chip circuit attached, and the voltage drops back to +-20, but of course, the amp doesn't work. What do I make of this?

thanks,

tim schaefer
Attached Images
File Type: jpg 1 copy.jpg (45.8 KB, 287 views)
  Reply With Quote
Old 15th January 2004, 03:19 PM   #2
diyAudio Member
 
Join Date: Oct 2002
Location: pittsboro, NC
1) The 0 wire must connect to PSG for the gainclone to work. Please examine the transformer/bridge in the diagram at this link:
Noise in CG
This wire (the 0) is the "power" ground and can (sometimes) effect the sound output if it is connected incorrectly.

There is good info here:
http://www.decdun.fsnet.co.uk/gaincloneFAQ.html
look under "How do I wire up the transformer".

2) You are measuring "pulsating" DC voltage out of the Bridge Rectifier. When you connect it to the GC the large filter capacitors attached smoth (filter) the pulses and the DC voltage is higher.
  Reply With Quote
Old 15th January 2004, 05:04 PM   #3
diyAudio Member
 
Join Date: Mar 2003
Location: austin, tx
thanks for the links. they looked familiar; I'm sure I wired my original amp based off of the decibel dungeon diagram originally. Just a little rusty with time....
  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
Negative volts and grounding in bench power supply falcott Parts 11 29th April 2011 03:42 PM
Grounding for Mixer and Bipolar Power Supply bbmonster Instruments and Amps 1 20th March 2009 07:59 AM
Outboard power supply grounding ? woody Power Supplies 5 3rd May 2008 09:24 PM
Power Supply Questions dezzz Chip Amps 3 13th August 2007 08:43 PM
Power Supply Questions wrl Parts 7 29th December 2003 05:06 AM


New To Site? Need Help?

All times are GMT. The time now is 12:40 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