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Vout always 0 volts with negative input values

 

Hello,

I am trying to get a little deeper into LTSpice capabilities and I am having a problem?
understanding why, when using a voltage dependent voltage source with Table values,
the output plots 0 volts for negative values of input. I am using a 1Vpp sine wave as an
input.?

I have uploaded the spice value into the temp folder.

Any help is appreciated.

Thank you,
Joe McCarron
 

Think about what happens when the input exceeds the range of table values.? Read the Help file on the behavior of tables.


---In LTspice@..., <joemccarr@...> wrote :

Hello,

I am trying to get a little deeper into LTSpice capabilities and I am having a problem?
understanding why, when using a voltage dependent voltage source with Table values,
the output plots 0 volts for negative values of input. I am using a 1Vpp sine wave as an
input.?

I have uploaded the spice value into the temp folder.

Any help is appreciated.

Thank you,
Joe McCarron
 

Hello Spiceman,

I think I know what your suggesting the output will be the last value of output
if the input of the table is exceeded. But that isn't what is happening.

I have used negative values of input, for example this table.
table= ((0,0),(-0.25,0.5),(-0.5,0.75),(-0.75,0.90),(-1,1))

For the above table the output waveform is 0 for all negative values of the sine wave and 1 for all positive values.

I have two tables in my file stored as comments, one with positive values of input and one with?
negative values of input for the same output.?

?
 

Hello Jo,

> table= ((0,0),(-0.25,0.5),(-0.5,0.75),(-0.75,0.90),(-1,1))

The input values have to be defined in increasing order and I miss the positive input-values in your table.

I recommend to use a bv-source. Please try the following.

V=table(V(vin),(-1,1),(-0.75,0.90),(-0.5,0.75),(-0.25,0.5),(0,0), 0.25,-0.5, 0.5,-0.75, 0.75,-0.9, 1,-1)

Best regards,
Helmut
 

Hello Helmut,
That did work. Thank you very much.
Best?
Joe
 

Joe,

FYI, your uploaded schematic had nothing to do with the question you asked.

? ? "I have uploaded the spice value into the temp folder."

Your schematic doesn't have comments either.? Your reply said there were comments.? I'm guessing you accidentally uploaded the wrong schematic file.

Regards,
Andy
 

"Hello
? ? you know how the code was written so in ltspice ??
? ? ?I'm grateful that you've helped me
? ? ?Thanks



On Monday, December 24, 2018, 1:51:48 AM GMT+3:30, analogspiceman@... [LTspice] wrote:


?

Think about what happens when the input exceeds the range of table values.? Read the Help file on the behavior of tables.



---In LTspice@..., wrote :

Hello,

I am trying to get a little deeper into LTSpice capabilities and I am having a problem?
understanding why, when using a voltage dependent voltage source with Table values,
the output plots 0 volts for negative values of input. I am using a 1Vpp sine wave as an
input.?

I have uploaded the spice value into the temp folder.

Any help is appreciated.

Thank you,
Joe McCarron

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