hum,ground loop,earth loop problem with your answers please

frank2395

Member
2005-04-13 2:35 pm
AUD
Thank you,
I would like to make a definative and informative answer available to all that have searched this question (including me) with a one thread answer

Assuming all is ok with your grounding (star etc), and the chassis will be earthed for safety and only a loop is the problem.

We want to conect ground to earth but prevent a hum path

your opinions, diagrams and explinations on the following please:

a) why is there a need to conect ground to earth (floating / non floating)

b)[a]some have used a bridge between ground and earth, type and specs of bridge (part No.) with drawing and explination please

...some have used a bridge with other components between ground and earth, type and specs of bridge and components (part No's.) with drawing and explination please

c)some have used 2 diodes between ground and earth, type and specs of diodes (part No.) with drawing and explination please.

d)some have used a thermistor (CL60 ?) between ground and earth, type and specs of thermistor (part No.) with drawing and explination please

e)some have used a resistor (x ohm x watt) between ground and earth, type and specs of resistor with drawing and explination please

f) other ....

Please include your complete answers here so as all is in one spot.

Thank you all for your help in advance and I hope this will help those that are suffering or have suffered
 

Nelson Pass

The one and only
Paid Member
2001-03-29 12:38 am
All these things work, and dual supplies (one for each channel)
with the grounds isolated from each other through those
elements is also very helpful.

The use of Thermistors instead of power resistors is simply
that it's easy. Under ordinary conditions, the thermistor provides
some isolation resistance against ground loops while giving
a safety path for current leaking from primary to secondary
systems. If the leakage becomes large current, then the
thermistor heats up, providing a more efficient path. The idea
is to have the fuse blow before the thermistor.

Diode bridges accomplish much the same thing, and when I
use them, I use the big 35 amp rectifiers for the same reason
as above.

Also, try to have your power transformer at a distance from the
input circuit, and try rotating it for minimum noise.

I would also suggest looking at the ground arrangements
for the ZV1 project. www.passdiy.com