I'm back again.
I have found a bit of a strange behavior in LTSPICE.
I have included 2 screen snapshots to show my findings.
Both snapshots are of 2 different circuits, a project circuit and test circuit.
Both have 2 voltage sources both labeled V1 and V2
When I run the simulator on my main circuit which is on the left, I got different results to what I was expecting.
simulation... .dc V1 -15 -30 1 V2 15 30 1
V1 is a negitive supply Ie. positive grounded.
It simulated as I expected with a single diagonal line running from -30v to -15
simulating V2 gave me multiple parallel lines with no noticeable voltage drop.
This behavior occurs throughout the non-invertingmode circuit.
I then created a new test drawing as seen on the right.
simulation ... .dc V1 0 30 1 V2 0 30 1
I tried running V1 as a negative supply and as a positive supply and the results were once again as I expected.
But once again simulating V2 gave me multiple parallel lines with no noticeable voltage drop.
I swapped the names of the two supplies and still had the same results.
V1 as I expected, V2 not.
The simulation shown has both voltage supplies as positive output.
Does anyone have any idea why This should be happening?
Thank you.
BILL.
Bill,
I ran your simulation, I removed the Zener diodes D1 and D2. The Zener are not in my library of parts so they generate an error.
When you have multiple sources in the DC sweep statement like this:
.dc V1 -15 -30 1 V2 15 30 1
The two voltage sources V1 and V2 are not changed simultaneously.
The line is interpreted like this:
With V2 values of 15 to 30 step 1V sweep the value of V1 from -15V to -30V in 1V steps.
In the other words the simulation runs 16 times.
Solution
I have labelled the voltage at V1 In1.
I have replaced V2 with a behavioural voltage sourced and specified V=-V(In1)
Now, I only need to sweep V1
Model
ResultsRegards,
Jay_Diddy_B