#37 How to flip polarity of V ?

[Samir Sabri]

Hello

How would I create a netlist that has one voltage sources ( DC battery ) and a resistor, then to be able to flip the voltage source polarity and see effect on current at resistor? (negative or positive)

I've noticed that current sign of resistor depends only at n+ n- of resistor entry, regardless how V is connected.

An exampe with V source flipped and un-flipped would be highly appreciated.

Please advice, thanks.

[Samir Sabri]

Here is what I have:

R1 0 1 0.00001
R2 3 1 1
V1 5 2 1.5v
R3 7 6 0.00001
VR1 0 2 dc 0
VR2 4 3 dc 0
VV1 6 5 dc 0
VR3 4 7 dc 0

Where R1, R3 are wires, and R2 is resistor, VR1, VR2, VR3, VV1 are ameters.
I tried to flip n+ n- of V1 as:
V1 5 2 1.5v
and
V1 2 5 1.5v

but that did not change current sign applied on VR1, VR2, VR3, Only current at VV1 got flipped from 1.49997 to -1.49997

here is how I analyze:

.dc V1 1.5 1.5 1
.print dc
.print dc i(VR1) i(VR2) i(VV1) i(VR3)

what I expect that current sign at VR1, VR2, VR3 is affected too when flipping V, please explain.
Thanks

[Holger Vogt]

.dc V1 1.5 1.5 1
has wrong syntax (start and stop the same?, step does not fit)

For a single dc operating point use
.op

you may sweep V1 from -1.5 to 1.5 in one step (yielding two values for V1) by
.dc V1 -1.5 1.5 3

[Samir Sabri]

Thanks, but how would I actually apply the flip of dc voltage source? kindly have alook at the attached snapshot, what wolud be the netlist for such circuit? how would I get simulation results without using .op ? (notice the flipped battery)