Adding isolation

Thread Starter

liamstears

Joined Jan 31, 2013
26
So I have a power supply I need to add isolation to, this is the current design:

current-circuit.png

I have a JCA0612S12 DC-DC isolated converter I want to add to this circuit. What would be best practice? Would the following suffice?

proposed-circuit.png
 

crutschow

Joined Mar 14, 2008
29,800
According to the data sheet, that will provide isolation up to 500V between input and output if case is connected to one of the grounds, so your proposed circuit should work.

What is the 9V output used for?
 

Thread Starter

liamstears

Joined Jan 31, 2013
26
According to the data sheet, that will provide isolation up to 500V between input and output if case is connected to one of the grounds, so your proposed circuit should work.

What is the 9V output used for?
This is only to power a noisy 9v guitar pedal, I didn't plan on making any connection to the case, should I? Never used one of these before...
 

eetech00

Joined Jun 8, 2013
3,154
This is only to power a noisy 9v guitar pedal, I didn't plan on making any connection to the case, should I? Never used one of these before...
If you are referring to ground isolation...
Use a 12-14vdc wall wart to drive the 9v regulator or the DC-DC converter, or a 9vdc wall wart to drive the pedal directly.
 

Thread Starter

liamstears

Joined Jan 31, 2013
26
Don't see any particular reason to, unless it radiates switching noise into the system.
Thanks

If you are referring to ground isolation...
Use a 12-14vdc wall wart to drive the 9v regulator or the DC-DC converter, or a 9vdc wall wart to drive the pedal directly.
This is a multi pedal supply, powers 16 pedals total using multiple of the original schematic, have a couple that are radiating noise so adding these to isolate the grounds on the problem pedals (multiple tests using wall warts etc shows its a ground loop issue on this particular couple)
 

eetech00

Joined Jun 8, 2013
3,154
Thanks
This is a multi pedal supply, powers 16 pedals total using multiple of the original schematic, have a couple that are radiating noise so adding these to isolate the grounds on the problem pedals (multiple tests using wall warts etc shows its a ground loop issue on this particular couple)
Usually the wall wart will have a transformer inside, so it will inherently have an isolated ground. If the wall wart has an internal step-down transformer, and has a two prong AC plug, then the output will be isolated from the input.
If the wall wart has a three prong AC input plug, then you can easily test for ground isolation with an ohm meter: Check for continuity from the Wall warts AC input "ground plug" to the barrel of the Wall warts output plug. If isolated, there will be NO continuity. (do this test with no power applied of course).

I doubt the DC-DC converter will help if ground isolation is what you are trying to achieve. In fact, it may cause more noise problems than it solves.
 

Thread Starter

liamstears

Joined Jan 31, 2013
26
Usually the wall wart will have a transformer inside, so it will inherently have an isolated ground. If the wall wart has an internal step-down transformer, and has a two prong AC plug, then the output will be isolated from the input.
If the wall wart has a three prong AC input plug, then you can easily test for ground isolation with an ohm meter: Check for continuity from the Wall warts AC input "ground plug" to the barrel of the Wall warts output plug. If isolated, there will be NO continuity. (do this test with no power applied of course).

I doubt the DC-DC converter will help if ground isolation is what you are trying to achieve. In fact, it may cause more noise problems than it solves.
Why don't you think it will work? It's whole purpose is to isolate and the specs say it can...
 

eetech00

Joined Jun 8, 2013
3,154
Why don't you think it will work? It's whole purpose is to isolate and the specs say it can...
Isolate what?
What do you want to isolate that is not already isolated?

If your asking if DC-DC converter will power the regulator...yes.
If your asking if the DC-DC converter is going to provide ground isolation between the source and load....yes.
But the DC-DC converter won't provide anymore ground isolation than that already provided by a wall wart.
 
Last edited:

Thread Starter

liamstears

Joined Jan 31, 2013
26
Well I've put them in place and they have made a significant difference to the amount of noise, much much quieter but there is still a bit of noise but I'm not sure at the moment where exactly it's coming from so need to work that out

Quick question, these dc-dc converters, to get 500ma out what amperage input will it need at 12-13v?
 
Top