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Positive 1 supply to negative of another

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axro

New Member
If I have 2 wallwarts. And I connect The Positive of one to the negative of another(through a resistor of course) should I have a complete circuit?
 

audioguru

Well-Known Member
Most Helpful Member
Wall-warts usually have floating outputs. They can be connected in series without a resistor in between. In series their voltages add but the max current is the current of the lowest current one.
 

Hero999

Banned
If you want to make a bipolar power supply, it's better to use one AC wall wart and a voltage doubles circuit to get both positive and negative voltages.
 

axro

New Member
I'm not trying to double voltage or anything like that. I'm just doing some experiments.

I think you misunderstood how I connected them.

Say I have
Wallwart A (A traditional linear power supply)
Wallwart B (A Switching Supply)

I take the Positive end of B and connect it through a resistor to the Negative end of A.
So that would leave The positive of A unconnected and and the negative end of B unconnected.

Should I have a circuit or no?
 

Hero999

Banned
No you won't have a circuit because the two supplies are isolated from each other.
 

axro

New Member
I don't get that then. Why should it matter? Positive flows to negative. Excess of electrons flow to lack of electrons. There is a positive on Wallwart B, so why wouldn't thee electrons want to flow to the negative of Wallwart A. 0V is 0V right?
 

Hero999

Banned
Because you need a complete circuit for electrons to flow.

Try connecting two 9V batteries together (one positive terminal to one negative terminal) and measure the current flow; it should be 0A.
 
Last edited:

giftiger_wunsch

New Member
Positive flows to negative. Excess of electrons flow to lack of electrons.
Though it's convention in physics that 'current flows from positive to negative', I thought I'd point out that the two statements you just made there are completely incompatible since you're talking about positive flowing to negative but then referring to negative charge carriers, i.e. electrons.
 

Hero999

Banned
Yes, electrons flow from negative to positive, we've had threads 100s of posts long debating this before and I don't think there's any need to go down that route now.
 
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