Could anyone please advise what type of capacitor can be used for ground loop breaker (the one across the 10 ohms/5W resistor). Can I use one of these X2 type capacitor ?
MKP X2 capacitor 0.1uF, View x2 capacitor 0.1uF, TENTA (TC) Product Details from TENTA ELECTRIC INDUSTRIAL CO., LTD. on Alibaba.com
or
cheap ceramic (50V) is good enough?
Thanks.
MKP X2 capacitor 0.1uF, View x2 capacitor 0.1uF, TENTA (TC) Product Details from TENTA ELECTRIC INDUSTRIAL CO., LTD. on Alibaba.com
or
cheap ceramic (50V) is good enough?
Thanks.
As I would be uncomfortable with any more than 2 Volts of ripple on the ground return, I would suggest a 10R 1Watt resistor with 100nF 50Volt capacitor across it or better still remove the source of the ground loop.
Thanks for the reply. I understand that most people use 100nf but I am just wondering what type / spec of capacitor should I use.
Do you mean a standard 50V ceramic will serve the purpose and I don't need to look for high voltage capacitor.
I also noticed that the type X (the link in the previous) is used for line filtering (across 230V input) but not sure whether it is suitable for ground loop breaker.
The diode based loop breaker does not need a capacitor.
It is optional.
The purpose of the optional capacitor is to try to reduce the VHF impedance (for better attenuation of RF interference) but that can only be effective if the wires into and out of the loop breaker are very short.
It is optional.
The purpose of the optional capacitor is to try to reduce the VHF impedance (for better attenuation of RF interference) but that can only be effective if the wires into and out of the loop breaker are very short.
John,
did you read my report of the Live to Main Audio Ground to "test" my interpretation of the Disconnecting Network.
The 600mW 10r resistor not only survived the explosion of the mains fuses blowing, the resistor measured exactly the same as before the test !
As near as I could tell the tiny 50V 100nF ceramic capacitor also appeared to be totally undamaged.
Thanks Andrew. Since this is not a critical component, I will just use a 50V ceramic.
One more question:
Given the condition that AC neutral is connected to chassis. Is it correct to say that the ground loop breaker is still needed for safety reason even the amp doesn't have any noise (this is what you are trying to simulate in your test)?
As others have said this cap is non-critical; it's not even necessary but can help shunt HF to ground.
I use a plain ceramic cap with long leads that I can wrap around and directly solder to the rectifier terminals. Nice and easy. Film caps are unnecessary in this application and impractical due to their short legs.
I use a plain ceramic cap with long leads that I can wrap around and directly solder to the rectifier terminals. Nice and easy. Film caps are unnecessary in this application and impractical due to their short legs.
NO ! NO! No!
The Live and the Neutral MUST NEVER be connected to Chassis.
The third wire of the three in the Mains cable is the Protective Earth (PE). That PE, is the wire that MUST be connected to Chassis.
Thanks for pointing this out. What I really mean is Earth to Chassis ( the centre pin). I just mixed up the names.
OP you are wrong there - this is a safety critical circuit. What happens if someone swops the Live and Neutral around? Use a 100nF X2 capacitor rated at 275 Vac and don't compromise on safety with a ceramic cap of 50 volts! You don't need a snubber resistor either IMO
Swapping Live and Neutral around does not make any difference to the safety of a properly wired transformer.
Both Live and Neutral are a direct to Mains connection and both must be treated as potentially dangerous.
The Disconnecting Network is a circuit to convey Fault current from the Main Audio Ground to Chassis and thence to PE. Swapping L & N has absolutely no effect on this Disconnecting Network.
The main part of the network doing any real work is the Power Diode. The voltage across the Power Diode/s must be low during the Fault Current event. If it weren't, the mains fuse might not blow.
Once we have that low voltage across the diode/s that then allows low voltage components across the diodes to perform the supplementary task: Conveying VHF interference to Chassis.
X2 capacitor is specified for fitment from Live to Neutral.
There is no Live connection at the Disconnecting Network.
There is no Neutral connection at the Disconnecting Network.
Therefore it cannot be applicable to fit an X2 here for Safety reasons.
Learn how the Disconnecting Network works and learn why the components that I recommend are suitable for the duty.
Both Live and Neutral are a direct to Mains connection and both must be treated as potentially dangerous.
The Disconnecting Network is a circuit to convey Fault current from the Main Audio Ground to Chassis and thence to PE. Swapping L & N has absolutely no effect on this Disconnecting Network.
The main part of the network doing any real work is the Power Diode. The voltage across the Power Diode/s must be low during the Fault Current event. If it weren't, the mains fuse might not blow.
Once we have that low voltage across the diode/s that then allows low voltage components across the diodes to perform the supplementary task: Conveying VHF interference to Chassis.
X2 capacitor is specified for fitment from Live to Neutral.
There is no Live connection at the Disconnecting Network.
There is no Neutral connection at the Disconnecting Network.
Therefore it cannot be applicable to fit an X2 here for Safety reasons.
Learn how the Disconnecting Network works and learn why the components that I recommend are suitable for the duty.
here in the states the ground is connected to the same place in the circuit breaker panel as the "neutral"
rule of thumb is green to ground white is neutral and black is hot
rule of thumb is green to ground white is neutral and black is hot
Your comments are valid and I cannot fault them. I personally don't like ceramic capacitors for their obvious flaws such as poor frequency response (unless you use X7R caps) and their tendency to blow up under high voltage conditions.
X2 caps are self healing and are used in my amps and lighting surge protection modules for incoming mains surges.
The audio earth disconnect circuit is different - and I suggest using a small 10mm metal oxide varistor in place of a capacitor rated at the maximum DC supply voltage which will provide the required capacitance and add additional protection
You are correct.
However, you must heed Andrew's advice. The neutral is known as the "designated conductor" and should never, ever be connected directly to chassis. The ground wire is only to conduct a ground fault current to earth. You never want a fault current returning to earth through the neutral; in fact this would defeat the function of a ground fault circuit interrupter device. Andrew is absolutely correct when he says you should treat the neutral as a potential shock hazard.
If you don't understand this, just do it the way Andrew says.
"you should treat the neutral as a potential shock hazard"
the neutral is a shock hazard <--- there fixed that, as I work on outlets, and lighting at work and the neutral will shock you since many people do not hook the ground up properly.
(one of my pet peeves is opening up an outlet box or a florescent light fixture and the ground is no where to be found)
the neutral is a shock hazard <--- there fixed that, as I work on outlets, and lighting at work and the neutral will shock you since many people do not hook the ground up properly.
(one of my pet peeves is opening up an outlet box or a florescent light fixture and the ground is no where to be found)
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