# Feed AC circuit with DC?

#### Rorut

##### Member
I think I did not explain this clearly.
I dont have the mixer above with the D701.
I just want the circuit I first posted inside this (http://rasteri.com/w/images/b/be/PMC-05PRO.pdf) unit that is powered with an 15V DC supply, the internal PS in that just makes 15VDC to 12DC.

This is what my supply look like in the unit I where I want to use the positive/negative circuit.

Basically I need to do my own circuit that splits 15V DC to -7.5v +7.5v . Or 12DC to -6v +6v.
(If I understood it correctly).

Could also replace my external 15v DC supply to a 20V DC if this can give me -10v +10v. Have to adjust above circuit from 20V DC to 12V DC also if its needed.

Something like this?

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#### Rorut

##### Member
Correct thinking here?

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#### AnalogKid

##### Well-Known Member
The small schematic you posted is correct, although it is missing some filter components. Your drawing in #22 is missing too many lines to be evaluated. Draw and label every power and GND connection, complete with polarities. When splitting one supply into two, it is very easy to get something reversed or shorted.

ak

#### Rorut

##### Member
The small schematic you posted is correct, although it is missing some filter components. Your drawing in #22 is missing too many lines to be evaluated. Draw and label every power and GND connection, complete with polarities. When splitting one supply into two, it is very easy to get something reversed or shorted.

ak
Thanks!

The drawing in #22 is just an overall sketch/block diagram. No schematic

Would this work?

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#### dr pepper

##### Well-Known Member
If you wereusing the lower half of the circuit to power one piece of kit then that might well work fine.
Same goes for the upper half of your schem, that would probably work fine on its own.
However I see a potenitial issue, if the mixer is connected to whatever is powered by the lower half of your circuit, then the mixers ground connection would connect to the -10v rail from the lower sections circuit, shorting out the -10v rail through the audio connections.
If you have access to 2 x 20v supplies that might work, and keep them seperate from each other, or another bit of a kludge way is to use isolation transformers on one of the items, you can get them that fit inline with the audio connections.

Dc to Dc converters are handy, however for this application noise and ground loops might be a problem, seperate supplies is the best way if you can do it.

#### Rorut

##### Member
Thanks! Probably best to give up this idea. A bit more difficult to do for me than I first thought

#### dr pepper

##### Well-Known Member
Ok
But if you really need to get it done from what you've saud so far I think you'll be able to do it.

#### Rorut

##### Member
Ok
But if you really need to get it done from what you've saud so far I think you'll be able to do it.
Thank you for keeping me motivated!

Would be a nice and needed feature.
But Using two external supplys feels a bit cumbersome.

Wonder if its hard to trace the Single rail version of the send/return PCB that I posted an image of in an earlier post

It has almost the same amounts of components as the dual rails but different values on resistors.
Following every component and try draw a schematic from the pcb.

Never done something like that but it could work?
Just dont know in which end to start

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#### KeepItSimpleStupid

##### Well-Known Member
Everything starts on the napkin,

Napkin
Sketch/idea
Schematic
BOM
Case
Layout
PCB
Stuff
Test

#### rjenkinsgb

##### Well-Known Member
Everything starts on the napkin,
The best designs start on the back of a beermat, at least in England!

>end interruption<

#### Rorut

##### Member
Curious how they manage to do the circuit feeded with a single 12v supply (attached pcb) when the IC need dual supply. Green arrow pointing att red cable measures 12V.

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#### KeepItSimpleStupid

##### Well-Known Member
Curious how they manage to do the circuit feeded with a single 12v supply when the IC need dual supply. Green arrow pointing att red cable measures 12V.
You can bias the output of the op-amp at 1/2 the supply and capacitivly couple the input and output. But,it has to be DESIGNED that way/

#### dr pepper

##### Well-Known Member
Going back to #25, if you deleted the top half, then powered the mixer from 10v and 0v off the bottom half of the schematic on paper that would probably work.
The only thing is the current demand, the virtual ground would need to be rated at the current used ny both devices.
You could use something like a Tda2030 for the virtual ground, plus a couple of R's & C's.

#### Rorut

##### Member
I found the PCB layout for the DC version. Tried to clone it in diptrace

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