Hi,
I have attached an image of my understanding of a PSU connection. The bit I'm not sure about is the Earth wire. I know it's not strictly needed - but I'd prefer to have it there. These question apply for the UK - but they may be universal?
1) Do I need to attach Neutral to the Earth?
2) Is Ground and Earth the same thing?
3) What is the pinout for a three pin computer/kettle etc. cable (in the UK only?)
4) Are there any problems with the circuit as it stands?!
Thanks - please help me from blowing myself up!
Gaz
I have attached an image of my understanding of a PSU connection. The bit I'm not sure about is the Earth wire. I know it's not strictly needed - but I'd prefer to have it there. These question apply for the UK - but they may be universal?
1) Do I need to attach Neutral to the Earth?
2) Is Ground and Earth the same thing?
3) What is the pinout for a three pin computer/kettle etc. cable (in the UK only?)
4) Are there any problems with the circuit as it stands?!
Thanks - please help me from blowing myself up!
Gaz
Attachments
This should answer a few of your questions
The earth wire should not be connected to your circuit as you have it.
All power should return to Neutral. Earth should be connected to the chassis. You should also separate the signal ground from the power ground.
The earth wire should not be connected to your circuit as you have it.
All power should return to Neutral. Earth should be connected to the chassis. You should also separate the signal ground from the power ground.
Hi
The reason I did the diagram like that is because I thought the Earth went to the chassis and so did the HQG. Isn't that connected to ground too? Meaning that the Ground and Earth are all connected together.
But I need to connect the Neutral there aswell?
Thanks
Gaz
The reason I did the diagram like that is because I thought the Earth went to the chassis and so did the HQG. Isn't that connected to ground too? Meaning that the Ground and Earth are all connected together.
But I need to connect the Neutral there aswell?
Thanks
Gaz
Grounding can be confusing... There are the safety issues, and then the noise issues.
I'm not an expert, but here is my understanding:
The neutral should NOT be connected to the "Earth". The "Earth" connection is a safety ground - it should be connected to the chassis, and no current should flow through it under normal circumstances. It is there in case the Live wire should somehow contact the chassis. In this case, current will flow through the saftey ground and the fuse or breaker will trip, ensuring that the chassis doesn't become a shock hazard.
The centre tap on the transformer is a floating "common", or zero volt point. This is where your speaker return should connect. Your input return connects here too, though perhaps not physically - maybe it is better to physically connect the input return to the amp pcb? I'm not sure.
Now, as to whether the transformer common should connect to the chassis... Probably not directly. Maybe through a resistor or a rectifier, to eliminate noise.
I'm not an expert, but here is my understanding:
The neutral should NOT be connected to the "Earth". The "Earth" connection is a safety ground - it should be connected to the chassis, and no current should flow through it under normal circumstances. It is there in case the Live wire should somehow contact the chassis. In this case, current will flow through the saftey ground and the fuse or breaker will trip, ensuring that the chassis doesn't become a shock hazard.
The centre tap on the transformer is a floating "common", or zero volt point. This is where your speaker return should connect. Your input return connects here too, though perhaps not physically - maybe it is better to physically connect the input return to the amp pcb? I'm not sure.
Now, as to whether the transformer common should connect to the chassis... Probably not directly. Maybe through a resistor or a rectifier, to eliminate noise.
My opinions to your questions:
1.) No- it's already connected at your service panel.
2.) Yes -Ground (USA) Earth (GB)
3.) N/A
4.) a. Maybe--- depending on your xfmr/design, the two primary windings should be wired in parallel---not in series as you have drawn. (Assuming a standard four winding torid xfmr)
b. The secondary as drawn looks fine to me "if" the ground wires as shown are executed in the "star" method.
Good Luck!
1.) No- it's already connected at your service panel.
2.) Yes -Ground (USA) Earth (GB)
3.) N/A
4.) a. Maybe--- depending on your xfmr/design, the two primary windings should be wired in parallel---not in series as you have drawn. (Assuming a standard four winding torid xfmr)
b. The secondary as drawn looks fine to me "if" the ground wires as shown are executed in the "star" method.
Good Luck!
Hi,
Orcad wasn't set up to plot at angles so that's why it isn't in star form. 😉 As for the xformer...
It is a 2x115V primary so for 240V UK use, the primaries have to be in series.
Is it right that the Earth connects to the chassis / HQG point?
Thanks,
Gaz
Orcad wasn't set up to plot at angles so that's why it isn't in star form. 😉 As for the xformer...
It is a 2x115V primary so for 240V UK use, the primaries have to be in series.
Is it right that the Earth connects to the chassis / HQG point?
Thanks,
Gaz
As I mentioned before, the Earth (or Ground) MUST connect to the chassis for safety reasons. The "HQG" point should probably not be directly connected to the chassis for noise reasons - usually it is connected via a resistor or rectifier.
Take a look at the power supply schematic on this page (from passdiy.com):
http://www.passdiy.com/projects/zenv4-4.htm
Here you can see what I mean about connecting the common through a rectifier to the chassis.
Take a look at the power supply schematic on this page (from passdiy.com):
http://www.passdiy.com/projects/zenv4-4.htm
Here you can see what I mean about connecting the common through a rectifier to the chassis.
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