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LTSpice questions...

S

SA Dev

Jan 1, 1970
0
Hi,

I've downloaded and played around with LTSpice, but I have a couple
questions:

How do I put just a manual switch in there, like a momentary button? How
can I press or release this switch during a simulation?

Is there a way to make a LED actually light up, or do I need to watch the
voltage across it in the graph to see when it is on or off?

Is there other software that is more GUI friendly, such that I could press
on a switch or connect it to a keystroke to open and close it and watch LEDs
go on or off?

Thanks,

SA Dev
 
M

mikem

Jan 1, 1970
0
SA said:
Hi,

I've downloaded and played around with LTSpice, but I have a couple
questions:

How do I put just a manual switch in there, like a momentary button? How
can I press or release this switch during a simulation?

Look at the example "vswitch.asc" which comes with the download. It is
in the ...\examples\educational sub directory
Is there a way to make a LED actually light up, or do I need to watch the
voltage across it in the graph to see when it is on or off?

Is there other software that is more GUI friendly, such that I could press
on a switch or connect it to a keystroke to open and close it and watch LEDs
go on or off?


Electronic Workbench has some of these Gui gadgets; but the simulator sucks!
 
K

Ken Smith

Jan 1, 1970
0
Hi,

I've downloaded and played around with LTSpice, but I have a couple
questions:

How do I put just a manual switch in there, like a momentary button?

In click on the AND gate like symbol in the menu bar. Select the "sw"
item in the page that comes up.
How
can I press or release this switch during a simulation?

The "sw" is controlled by a voltage. Click on AND thingy again ands
select the voltage. Drop the voltage into the circuit. Right click on it
and click the advanced button. In the advanced window click on pulse and
then put in the following values:
Vinitial = -1.414E3
Von = 3.14159E3
Tdelay = 2.7
Trise = 1E-3
Tfall = 1E-2
Ton = 9.87654321

One of the nice things about the switches in spice is that they don't arc
when you put huge voltages on them. This should make a switch that closes
after 2.7 seconds and stays closed for 9.87654321 seconds. I'm sure this
will meet your needs. If not change the values
Is there a way to make a LED actually light up, or do I need to watch the
voltage across it in the graph to see when it is on or off?
Watching the voltage is better than any other option. If the LED actually
lit up, you'd only get to see it once.

Is there other software that is more GUI friendly, such that I could press
on a switch or connect it to a keystroke to open and close it and watch LEDs
go on or off?

There is software that is more drool resistant, but none that is truly
easier to use for something real. The folks at Linear (hi Mike) did a
nice job on the LTspice program. National's electronic workbench is about
the same to use.

For Linux there are some very nice programs that let you bypass all this
click here, click there, and click somewhere else stuff. With 101 buttons
on a keyboard, why would you need something else with too more buttons?
 
S

SA Dev

Jan 1, 1970
0
Ken,
The "sw" is controlled by a voltage. Click on AND thingy again ands
select the voltage. Drop the voltage into the circuit. Right click on it
and click the advanced button. In the advanced window click on pulse and
then put in the following values:
Vinitial = -1.414E3
Von = 3.14159E3
Tdelay = 2.7
Trise = 1E-3
Tfall = 1E-2
Ton = 9.87654321

Got you--I'll try that out!

Thanks for the info!

SA Dev
 
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