LTspice/SWcadIII

[bananasiong]

Hi,
I'm currently learning this simulator, LTspice. I've found some problems:
*I couldn't find an ammeter. I can measure the voltage when click run, then I used the red probe.
*How if I want to measure the Vce of a transistor? When there is a emitter resistor over there.
*I couldn't create AC source.

Anyone familiar with these?

Thanks

 

[eng1]

Hi,
I'm currently learning this simulator, LTspice. I've found some problems:
*I couldn't find an ammeter. I can measure the voltage when click run, then I used the red probe.
*How if I want to measure the Vce of a transistor? When there is a emitter resistor over there.

Click "Add Trace": you can select a trace (voltages or currents) or enter an expression. For example if you want to measure Vce of the transistor, you can label the collector (C) and the emitter (E), then plot V(C)-V(E).

*I couldn't create AC source.

Right-click on a voltage source, click "Advanced" and enter the AC properties.

 

[bananasiong]

Right-click on a voltage source, click "Advanced" and enter the AC properties.

I've tried that, but there are a lot of settings. I know the amplitude, frequency, DC offset. Some I left blank. But I couldn't get sinewave.
Besides, what's the setting of the simulation time usually?

Thanks

 

[eng1]

I've tried that, but there are a lot of settings. I know the amplitude, frequency, DC offset.

That's enough to generate a sin wave. See the pictures below. I plotted a 1000 Hz sine wave, the amplitude is 1 V. You can choose the "Stop time" for the transient analysis in order to see a few periods of the wave. In my example T=1/1000=1 ms and the stop time is 20 ms => 20 periods

 

[bananasiong]

I should have got the sine wave, I put 1 kHz frequency, but the simulation stop time was 4 us, LOL that's why I got a straight 0 V.
Thanks dude.

 

[Roff]

Hi,
I'm currently learning this simulator, LTspice. I've found some problems:
*I couldn't find an ammeter. I can measure the voltage when click run, then I used the red probe.

Move the mouse to the terminal where you want to measure current. The mouse turns into a black current probe symbol. Left-click the mouse.

*How if I want to measure the Vce of a transistor? When there is a emitter resistor over there.

Put the mouse on the collector and notice the red voltage probe that appears. Hold down the left mouse button and drag the probe to the emitter. Release the mouse button. Vce will display on the waveform plot. This works for any differential voltage measurement you want to make.

*I couldn't create AC source.

You already know how to make a sine wave in the time domain. If you want an AC source for frequency-domain analysis, right-click on a voltage source (battery or voltage symbols in the library), click on "none" in the functions area, then in the Small Signal AC analysis area, put a "1" in the AC amplitude box.

Anyone familiar with these?

Thanks

 

[bananasiong]

Can new devices added to LTspice? Those IC apart from the products of Linear Technology.

 

[Roff]

Can new devices added to LTspice? Those IC apart from the products of Linear Technology.

Yes.
Has Superman read the help file? Has he discovered the fine **broken link removed**? Was my previous post the least bit helpful?

 

[bananasiong]

Yes.
Has Superman read the help file? Has he discovered the fine **broken link removed**? Was my previous post the least bit helpful?

Your post was clear and easier to understand, thanks especially the Vce part.

Instead of getting the voltage reading from the graph, can I get the voltage reading next to the probe? This would be easier if there are more measurements to be taken.

Thanks

 

[Roff]

Your post was clear and easier to understand, thanks especially the Vce part.

Instead of getting the voltage reading from the graph, can I get the voltage reading next to the probe? This would be easier if there are more measurements to be taken.

Thanks

Sorry if I sounded harsh in my previous post, but it is rather discouraging to post exact answers to all your questions and just get another question back. You might want to remember that.
To answer your last question, no, this is not possible. If you are wanting to display a single voltage or current, such as with a multimeter, this would only be useful in a DC operating point simulation. When you run a DC operating point sim, ALL node voltages and branch currents are displayed in a text window (try it).

 

[bananasiong]

Hi,
Thanks for that, Ron H, I got it.
I've just joined Yahoo! group on LTspice. Just realized that there is SPICE directive. All I knew was only assembler directives
From the link: **broken link removed**
It says that the voltage, current and power can be shown when the cursor is pointed to the node. But what I got was only the voltage.

BTW, my exam is coming soon , couldn't spend much time in learning this new simulator (new for me) :sad:

 

[jvjtech]

Can new devices added to LTspice? Those IC apart from the products of Linear Technology.

Yes. I have posted this information in another thread. Regards. jvjtech

 

[audioguru]

The new version from Linear Technology is called LTspice IV.