Where to tie negatives together for Elk M1 and P124

[AnotherOne]

I'm adding a P124 power supply to my system and am seeing all the topics recommending you tie the negatives together. Is the best way to accomplish this to just run a wire from the VAUX negative of the M1 to the negative on the P124 board?

 

[Spanky]

Connect a negative terminal on the M1 to the negative terminal on the P124.

 

[RichardU]

Connect a negative terminal on the M1 to the negative terminal on the P124.

Hate to be dense, but which negative terminal on the M1 are you talking about. The OP mentioned the negative on the VAUX. Is that appropriate or should it be something else?

Richard

 

[Digger]

Connect a negative terminal on the M1 to the negative terminal on the P124.

Hate to be dense, but which negative terminal on the M1 are you talking about. The OP mentioned the negative on the VAUX. Is that appropriate or should it be something else?

Richard

All of the negatives are the same. Its a system common.

 

[WayneW]

All of the negatives are the same. Its a system common.

Except for the siren (output 2) negative, if memory serves me correctly.

 

[rfdesq]

Except for the siren (output 2) negative, if memory serves me correctly.

Memory served you correctly, been there, done that.

 

[IVB]

If you have 3, it doesn't matter if I daisy-chain them versus homerun to the Main elk, right?

I (will) have 2 power supplies in a 2ndary location, with the main elk being the 3rd. Would be simpler to run one wire from the main to one of the secondaries.

 

[Sacedog]

Also, do you have to tie the negatives together for a 412 power supply too?

 

[123]

Yes. It was recommended to me by Rfdesq and other Cocooners. It stems from the need for the supplies to share a common reference.

Sometimes its hard to see the need for something unless you consider an extreme example. Grab a magical voltmeter and put its positive lead on the positive terminal of a 12VDC supply. Now connect its negative lead to the negative terminal of a 12VDC supply here in Montreal (I told you it was magical). Are you 100% certain it'll read 12 volts? If two supplies don't share a common ground, there's no certainty about voltage levels.

 

[rfdesq]

Yes. It was recommended to me by Rfdesq and other Cocooners.

And it was recommended to me by Spanky and Kirk.

 

[IVB]

so...daisy chaining okay?

 

[rfdesq]

so...daisy chaining okay?

I think daisy chain will work just fine. Electrically it should all be the same.

 

[Photon]

As this wire is for a voltage reference, I assume a single 24 AWG cat 5 conductor is adequate. No? How much current does this wire carry?

 

[123]

Now that's a good question! Theoretically, there's no potental difference (i.e. 0V) between the two negative terminals so there's no current flow. Ahem, theoretically. Now what happens if something does go screwy and there is a current flow?

Hope for the best but plan for the worst ... I used the same wire gauge throughout (16 AWG).

 

[Sacedog]

So, just to make sure, I am connecting a single wire from the VAUX NEG terminal on the M1 to the negative output terminal on the P624. Is that correct??