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Current and Voltage Sources....

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I have come across the fact in quite a few books that 2 current sources should never be connected in series unless they supply the same current.Similarly,2 voltage sources should never be connected in parallel unless their terminal voltages are the same.Now the explanation which was given is that it would damage the circuit/equipment.Can anyone tell me what really happens????
 

Grossel

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Well, I can tell that's exactly what happens. A practical voltage source might be a big car battery (12V). Another one could be a truck battery (24V). I you have same ground, and connect the two plus poles of the batteries, you'll probably get a hell of a sparkle. Burning injuries and other damages, plus the two batteries is most likely to get damaged.

A practical current source is almost non-existing. You could easilly make one out of opamps, but it has only one pole. So it's almost impossible to connect two such circuits in series because they ar likely to use the same voltage supply.
And IF they had no connection between (two independed circuit boards with theyr own pack of batteries) then the current source that provided least current would having as low or negative voltage as it could.
 

crutschow

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The point is, if the two currents or two voltages are not identical, then the larger one will try to drive the smaller one to be equal to the larger one, and it's likely that one of them (usually the smaller one) will be damaged by that.
 

Grossel

Well-Known Member
The point is, if the two currents or two voltages are not identical, then the larger one will try to drive the smaller one to be equal to the larger one, and it's likely that one of them (usually the smaller one) will be damaged by that.
Yess we know that part. Wich battery is the smaller one?

And - Show me two (or more) current sources that is connected in series. Schematic should be provided :D
 

crutschow

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Most Helpful Member
Yess we know that part. Wich battery is the smaller one?

And - Show me two (or more) current sources that is connected in series. Schematic should be provided :D
The smaller battery is the one with the lower voltage.:rolleyes:

To connect two current sources in series (although there's unlike to be a practical reason to do so) just use two lab supplies with isolated outputs, each configured to output a constant current.
 

Grossel

Well-Known Member
Current sources in series.
This schematic kill the idea about the current source providing the least current will be damaged. This must be considering a safe current source.

But this drawing shows not two independent current sources as they share the same voltage supply. So the very damaging way to connect two (theoretically) current sources must be different from this.
 
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