LT Spice For Radio Amateurs: PART 1

Ok, so sometime ago I started writing a series of articles for the WIA AR Magazine from a beginner to homebrew persective. Now for various reasons of no real importance to this story part way though i changed my mind and pulled the pin on the whole thing, but I still have my original files and so now seems as good a time as any to edit them up, add some more information and present them here for those who might be looking for a very basic intro into LT Spice.

I am going to assume you know how to download and install the software and get it up and running. And I am only going to gloss over using the interface and get straight into building basic circuits in the program and testing them. For some circuits I will provide the LT Spice files, for others I will not. The whole point about this series is to learn HOW TO DO IT, not just play with the crap I have already done.

So, lets get into it.

The Interface:

Everything you need to know is pretty much in this one picture. So run the program, click FILE->NEW SCHEMATIC and start clicking things.

  1. The Scissors: are used to remove components and wires when you stuff things up.
  2. The Pencil: is used to connect parts together with wires.
  3. Ground: every circuit has to have a ground point. It wont work without one.
  4. Label Net: Meh kind of ignore this for now.
  5. Resistor: used to place resistors in the circuit.
  6. Capacitor: used to place caps in the circuit.
  7. Inductor: used to place inductors in the circuit.
  8. Diode: used to place diodes in the circuit.
  9. Components: components are things like IC’s, transistors, voltage and signal sources.
  10. The Hands: used to move things or drag things around in the schematic.
  11. Text: to add notes to the schematic.
  12. Spice Directive: High end feature used for making complex inductors like bifilar and trifilar windings.

 

When you place a passive component in the schematic it has no value. To set its value you right click on it and this window pops up. You can enter the values in Ohms, Farads or Henry’s and thats ok if you know exponential notation, or you can shorthand things for resistors 10R, 10K, 10M will be 10 ohms, 10,000 ohms and 10 million ohms, capacitors 10pf, 10nf, 10uf for pico, nano and micro farads, and inductors 10nh, 10uh for nano and micro henry’s.

 

Finally, components, the main things we will be placing are NPN transistors, N type MOSFETS and Voltage Sources. Voltage sources can be DC or AV volts like for powering things and they can also be AC Signal Sources.

And with that, you now know how to place components into a schematic and find all the parts for might need to build, test and simulate many different circuit types in LT Spice.

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2 thoughts on “LT Spice For Radio Amateurs: PART 1

  1. i Installed LTSpice for OSX and it looks awful. No menubar, you have to right click to find a menu to add components. Is my install messed up or is the OSX port just ugly?

    1. Sorry I cannot help you, I do not run OSX and have no experience with it. Run the windows version under an emulator would be my only suggestion.

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