First Lm3886

[PJPro]

What is the usual way to implement the above circuit? Point to Point? Protoboard?

[infinia]

Originally posted by PJPro
OK. I assume that you mean something like this?



It would be useful to be able to bypass this unless needed. Any hints on the parameters for the switch? How much current should it be able to pass?

Bypass ? I would just delete pending anyone (Andrew?) objects strongly. I think this relates to some unlikely double fault transformer safety condition. (ie total meltdown for an approved, tested, modern, and light duty transformer?) china syndrome circuit anyone

[pacificblue]

Originally posted by infinia
No modern commercial gear that I know does.

Most commercial gear is Class II.

Originally posted by infinia
I think this relates to some unlikely double fault transformer safety condition. (ie total meltdown for an approved, tested, modern, and light duty transformer?) china syndrome circuit anyone

This circuit can help against ground loops in Class I equipment. As long as there is no hum without it, it is better to skip the circuit and make a direct connection from audio ground to case, thus to PE. The circuit will isolate ground from chassis/PE for line level signals thus avoid a ground (hum) loop through that path. In case if a fault it provides a path to PE for shorts to ground, so that a short-circuit current can flow and blow the fuses. There is no double fault necessary, just a mains wire that comes loose and touches some conductive part in the audio circuit.

[PJPro]

Originally posted by pacificblue

This circuit can help against ground loops in Class I equipment. As long as there is no hum without it, it is better to skip the circuit and make a direct connection from audio ground to case, thus to PE. The circuit will isolate ground from chassis/PE for line level signals thus avoid a ground (hum) loop through that path. In case if a fault it provides a path to PE for shorts to ground, so that a short-circuit current can flow and blow the fuses. There is no double fault necessary, just a mains wire that comes loose and touches some conductive part in the audio circuit.

OK. I'm going to put this in place, complete with switch.

[AndrewT]

BTW,
the switch is sometimes referred to as a ground lift switch.
Note, it does NOT break the route for Fault Current to flow to Safety Earth.

Any other implementation of supposed ground lift switch which breaks the route for Fault Current to flow to Safety Earth is potentially very dangerous.

I would just delete (the Disconnecting Network)

Infinia.
delete the connection between Safety Earth and the remainder of the circuit at your own risk. Face the consequences if you ever kill anyone by doing so.
Those are your decisions and we cannot stop you doing this.
Do not suggest that anyone on this Forum should consider copying that stupidity.

If instead you meant to say "make a direct connection from the circuit to Safety Earth" then say that.

[PJPro]

Originally posted by AndrewT
BTW,
the switch is sometimes referred to as a ground lift switch.
Note, it does NOT break the route for Fault Current to flow to Safety Earth.

Any other implementation of supposed ground lift switch which breaks the route for Fault Current to flow to Safety Earth is potentially very dangerous.

I assume that if I implement the circuit as illustrated above, I shall be OK.

[AndrewT]

Originally posted by PJPro
I assume that if I implement the circuit as illustrated above, I shall be OK.

yes, you must permanently connect all exposed conductive parts to Safety Earth.

[infinia]

If instead you meant to say "make a direct connection from the circuit to Safety Earth" then say that.

Uhh... I did say that in my previous post ie earth to chassis connection. I'm just objecting to the wacky network that appeared later.

Why do we need class II equipment in a home appliance. The amp will be safe and there will be NO hum without that "china syndrome" network. I'm certain of that, but the fact that a bypass switch is contemplated means that you are not.

What are the labels for the switch? hahaha
Safe/Unsafe
Hum on/ Hum off
ClassII/ClassI

[AndrewT]

Originally posted by infinia
Why do we need class II equipment in a home appliance.

to make it cheap to manufacture.
Because we as consumers vote with our feet, we go out and buy the cheapest we can find even though we know it cannot do the job reliably and that it cannot be repaired economically and that it will be obsolete within weeks (because the next series of advertisement will tell us that). We throw the Class11 product in the bin for someone else to dispose of and buy more cheap product in whatever flavour of the month.

[AndrewT]

Originally posted by infinia
What are the labels for the switch? hahaha
Safe/Unsafe
Hum on/ Hum off
ClassII/ClassI

that is a S.....d remark that shows you do not understand what we are showing the rest of the Forum.