555pwm, same duty cycle, varying frequency & vica versa

SgtWookie

Joined Jul 17, 2007
22,230
Wookie, your triode example works for me, but I can't figure out how to do the same thing with a different symbol and .lib file.
Did you open the r_triode.sym file and edit the attributes?

You'll see Rydel_triodes.lib on the last line of the attributes panel.

It might be easier to put the library name in the SpiceModel field, and type in a default .subckt name that exists in the library into the Value field.

If the text you put in the Value field doesn't correspond to an existing .subckt in the .lib or .sub file, you won't get the scrolling list.

I started using the SpiceModle field for everything because I got tired of cluttering up my schematics with .lib statements, and it was annoying when a simulation would blow up because I forgot to include it.
 

Thread Starter

magnet18

Joined Dec 22, 2010
1,227
I've attached pot.zip.

Put the .sub file in Program Files\SwitcherCad\lib\sub
Put the .sym file in Program Files\SwitcherCad\lib\asy

If LTSpice is open already, it won't "see" pot.sym until you close and re-run LTSpice.
I don't have those paths, could it be Program Files (x86)\LTC\LTspiceIV\lib\sub?
and then Program Files (x86)\LTC\LTspiceIV\lib\sym?
 

SgtWookie

Joined Jul 17, 2007
22,230
I'm running Windows XP Pro, you seem to be running Windows Vista 64bit or Windows 7 64bit.

Also, I installed LTSpice when it was version III, so my directory structure looks a bit different.

If the directory tree you wrote about:
\Program Files (x86)\LTC\LTspiceIV\lib\sub
\Program Files (x86)\LTC\LTspiceIV\lib\sym
... currently exists, then yes - that's where they go.
 

Thread Starter

magnet18

Joined Dec 22, 2010
1,227
Thanks :)

One more question...
in the datsheet fot the TL071, here, (page 4) it has offset N1 and offset N2 for the symbols where you had the Vcc and Gnd. and the pin layout has Vcc+ and Vcc- pins, which of these do I use?

[EDIT]
After looking at the schematic on page 5, I'm assuming I'm supposed to leave the offsets alone and use the ±Vcc pins, but I don't know for sure... :confused:
 
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SgtWookie

Joined Jul 17, 2007
22,230
The model for the TL071 doesn't have the offset inputs, unlike the real TL071.
For this circuit, the offset inputs are in no way critical. If the gain were say, between 10 and 1,000 or so, and we were trying to do some kind of precision amplification, then it would be an issue.

I'm using the +V, -V, noninverting (+), inverting (-) and output terminals.
 

RRITESH KAKKAR

Joined Jun 29, 2010
2,829
Hi guys, I'm planning on building a plasma speaker and using it for a science far project, using a 555 and an ignition coil, but for this i need a way to change the duty cycle without changing the frequency and vica versa, how can i do this using a simple astable configuration like such?

Hi, what this plasma speaker??
 

Thread Starter

magnet18

Joined Dec 22, 2010
1,227
I'm back :)
Is it possible to use an electrolytic capacitor of the 2.2μF?
because I don't have any ceramic nearly that big and I am unsure the effects of an alternating current on a capacitor with polarity.
 

SgtWookie

Joined Jul 17, 2007
22,230
I didn't notice that you'd taken the schematic I posted and edited it. :rolleyes:

Now I don't know what you're trying to simulate or build.

Post your schematic.
 

Thread Starter

magnet18

Joined Dec 22, 2010
1,227
I didn't notice that you'd taken the schematic I posted and edited it. :rolleyes:

Now I don't know what you're trying to simulate or build.

Post your schematic.
I did?
Want me to put your name on it from now on? ;)
I didn't think I edited it any, just added the driver, FET, and fly-back.
In any case, I'm currently just trying to build the original schematic you posted.
 

SgtWookie

Joined Jul 17, 2007
22,230
Yes. Look at the schematic you edited in reply #17, on the 2nd page of this thread. It won't work like that.

Want me to put your name on it from now on? ;)
Actually, I'm using custom colors and other settings for my install of LTSpice which I find more pleasant and "friendly" than the defaults. It's not difficult for me to tell whether they've been changed or not, as I keep the originals around.

I didn't think I edited it any, just added the driver, FET, and fly-back.
In any case, I'm currently just trying to build the original schematic you posted.
I'll save you the trouble and attach it to this post.
 

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Thread Starter

magnet18

Joined Dec 22, 2010
1,227
Yes. Look at the schematic you edited in reply #17, on the 2nd page of this thread. It won't work like that.
Oh! the RC thing, I was just making sure i knew what an RC network was, i didn't expect that to work and im not using it, just your origional.

I'll save you the trouble and attach it to this post.
And I meant in real life, where the 2.2μF capacitor is; it would be OK if I used an electrolytic there as long as the -lead is connected to the audio, right?

(and when I opened that I got an error "couldn't find symbol(s) TL07x")
 

SgtWookie

Joined Jul 17, 2007
22,230
Drat; forgot to add the TL07x in the opamp.zip.
Attached.

As long as the polarity across an electrolytic cap is always correct and you don't need a really low ESR, you can use one.
 

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Thread Starter

magnet18

Joined Dec 22, 2010
1,227
2 questions about spice
1. Is simulation time an issue, you mentioned earlier that you made a capacitor smaller to make the simulation run faster, as it is I ran the simulation in a few seconds
2. How do you separate the waveforms onto separate graphs?
 

SgtWookie

Joined Jul 17, 2007
22,230
2 questions about spice
1. Is simulation time an issue, you mentioned earlier that you made a capacitor smaller to make the simulation run faster, as it is I ran the simulation in a few seconds
I have only so much time during the day to make schematics and perform simulations for other people, therefore I take some shortcuts just to demonstrate that a circuit could be viable.

I increased the size of the timing capacitor so that the "tri" wave generator simulation would finish significantly faster.

2. How do you separate the waveforms onto separate graphs?
A) Run the simulation.
B) Click on a wire or component to plot the waveform.
C) On the plot pane, right-click and select "Add plot pane".
D) Select more signal(s) to plot.
E) To plot in a new pane, go back to step C)
 
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