Connecting cases to ground - 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 6th March 2004, 11:57 PM   #1
fedde is offline fedde  Netherlands
diyAudio Member
 
Join Date: Jul 2002
Location: Eindhoven, the Netherlands
Send a message via ICQ to fedde
Default Connecting cases to ground

Hi DIY fellows,

usually, I use a 220 ohm resistor parallel with a 220 nF capacitor to connect the case with the ground of my opamp circuits. I wonder if any theory exists why these (or similar) values should be used !?

The result on two variables can be considered:
- The amount of noise that is added to the ground
- The shielding properties of the case (Faraday cage)

Any information would be appreciated!

Fedde
__________________
http://www.fedde.nu, gainclone and non-oversampling DAC audio projects and kits...
  Reply With Quote
Old 10th March 2004, 07:14 PM   #2
fedde is offline fedde  Netherlands
diyAudio Member
 
Join Date: Jul 2002
Location: Eindhoven, the Netherlands
Send a message via ICQ to fedde
Anyone, p-p-p-please !?

Fedde
__________________
http://www.fedde.nu, gainclone and non-oversampling DAC audio projects and kits...
  Reply With Quote
Old 10th March 2004, 07:16 PM   #3
diyAudio Member
 
Peter Daniel's Avatar
 
Join Date: Jul 2002
Location: Toronto, Canada
Send a message via AIM to Peter Daniel
It seems like 220ohm is a bit high. Usually 10ohm is being used.
  Reply With Quote
Old 10th March 2004, 07:44 PM   #4
diyAudio Member
 
breguetphile's Avatar
 
Join Date: Mar 2003
Location: Indiana, USA
A step further than just a low resistance would be what alephs use. If you use a thermistor which will only be resistive when current is flowing, otherwise its close to 0 ohms. This is described in one (if not more) of the aleph service manuals.
__________________
Dawn: When men of reason go to bed. ~Ambrose Bierce
  Reply With Quote
Old 10th March 2004, 09:02 PM   #5
fedde is offline fedde  Netherlands
diyAudio Member
 
Join Date: Jul 2002
Location: Eindhoven, the Netherlands
Send a message via ICQ to fedde
Guys, you have no idea how thankful I am !!!

I will come back soon with a full report, but I think my amp is twice as chilling as before...
(just solved one of the biggest problems I still had)

Fedde
__________________
http://www.fedde.nu, gainclone and non-oversampling DAC audio projects and kits...
  Reply With Quote
Old 10th March 2004, 09:23 PM   #6
diyAudio Member
 
uvodee's Avatar
 
Join Date: Aug 2002
Location: Washington
Quote:
Originally posted by fedde
(just solved one of the biggest problems I still had)
Fedde [/B]

DIYaudio does it again.... if everything would be this easy .....

J-P

ik hou van Holland, landje aan de Zui......
  Reply With Quote
Old 11th March 2004, 06:57 AM   #7
Mad_K is offline Mad_K  Norway
diyAudio Member
 
Mad_K's Avatar
 
Join Date: Sep 2002
Location: Norway
Quote:
Originally posted by breguetphile
A step further than just a low resistance would be what alephs use. If you use a thermistor which will only be resistive when current is flowing, otherwise its close to 0 ohms. This is described in one (if not more) of the aleph service manuals.

Yup, I always do it like this. EXCEPT that you must use a NTC, not a PTC. This means that it should be about 5-10ohms when little or no current is flowing throug your ground, but it drops to a very low value when conducting any significant current. Another elegant solution would be to use a std rectifier bridge as in ZV4.
__________________
Mads K
  Reply With Quote
Old 11th March 2004, 07:08 AM   #8
diyAudio Member
 
Join Date: May 2001
Location: London UK
Quote:
Originally posted by Peter Daniel
It seems like 220ohm is a bit high. Usually 10ohm is being used.
----------------------------------------------------------------
Theses things sre done in 110V areas. Be careful in 220V region. I don't believe one should connect reoung to chasis via any resistor!

Even the Japanese have abandoned this practice, but still seems to take place in Taiwan.

  Reply With Quote
Old 11th March 2004, 09:55 AM   #9
fedde is offline fedde  Netherlands
diyAudio Member
 
Join Date: Jul 2002
Location: Eindhoven, the Netherlands
Send a message via ICQ to fedde
I have a tiny bit of hum if I don't connect the case to ground (the transformers are in the same case). I now connect the case directly to ground. I'll try 10 ohm too...

Fedde
__________________
http://www.fedde.nu, gainclone and non-oversampling DAC audio projects and kits...
  Reply With Quote
Old 11th March 2004, 03:08 PM   #10
diyAudio Moderator
 
pinkmouse's Avatar
 
Join Date: Apr 2002
Location: Chatham, England
Just a quick note, but using anything in line with the connection between chassis and the ground is bad practise, and, AFAIK, against IEE wiring regulations as being unsafe. It is also not really needed, if you think about your wiring and earth loops properly.
__________________
Rick: Oh Cliff / Sometimes it must be difficult not to feel as if / You really are a cliff / when fascists keep trying to push you over it! / Are they the lemmings / Or are you, Cliff? / Or are you Cliff?
  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
Should I directly connect my signal ground to chassis ground? Bricolo Solid State 4 18th March 2014 09:42 PM
connecting audio ground to Safety Earth AndrewT Power Supplies 41 30th May 2011 10:50 AM
Parallel LM3886, input ground, power ground, safety resistor and oscillations. markiemrboo Chip Amps 5 9th August 2007 03:50 PM
Connecting Virtual Ground Circuits with True Ground circuits?? Minion Solid State 1 12th February 2007 01:28 AM
does connecting mains ground with circuit ground create a ground loop? jarthel Everything Else 0 25th June 2003 12:55 PM


New To Site? Need Help?

All times are GMT. The time now is 07:11 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