Oops, I should have said "K" command/component, not "M". Oli has the correct version. On Sat, Nov 12, 2011 at 1:13 PM, Oli Glaser wrote= : > > On 12/11/2011 17:21, Sean Breheny wrote: >> Hi Mario, >> >> LTSpice handles transformers by using two inductors with a mutual >> inductance (the .M command). You can specify all the usual parameters >> of the two inductors and then for the mutual inductance, you specify a >> "coupling factor" K. >> >> As for a spark gap - there is no built-in model for that. You will >> have to make one yourself out of the other components which are >> available. Depending on what you need to simulate, this may be >> difficult. You will need to be aware of all the relevant properties of >> spark gaps - you can't use LTSpice to "learn" about the properties of >> spark gaps - you can only use it as a simulation engine to run your >> own model of a spark gap. >> >> Sean >> > > I was just about to say much the same as Sean, but his post popped up > first. > As mentioned you need to specify a coupling between two inductors to > make a transformer. > Add a SPICE directive, for example: > K1 L1 L2 0.99 > This will create a coupling between L1 and L2 of 0.99 (factor can be > from 0 to 1) > For the spark gap, there isn't one in LTSpice. There are usually only > the common components included with SPICEs. Floating around on the web > are various SPICE models of the more exotic variety (e.g. motors, > valve/tubes, etc) > What you would need to do is make your own based on the breakdown > properties of air. > As SPICE is basically a mathematical modelling tool, it can > theoretically be used to simulate just about anything (e.g. fluid > dynamics, thermal properties, magnetic circuits, etc) > I would search for some info on SPICE commands (all about circuits has a > basic intro IIRC) or grab a book that goes into greater detail. Once you > know what the various parameters do in the .model file, you can set it > up to match whatever function describes a spark gap and add variable > parameters for gap length, maybe even humidity and any other factors. > You could probably take a diode as a rough template for a spark gap > (e.g. adjust foward/reverse voltage to necessary voltages) > Or maybe a voltage controlled switch might be good enough. Have a look > in the LTSpice help under circuit elements for information on the switch > and other things. > Whenever I need a model that LTSpice doesn't have, I try Googling > " SPICE". I just tried this with "Spark gap SPICE", and came up > with the following, hopefully they will help get you started: > http://www.edn.com/archives/1997/070397/14di_06.htm > http://www.spectrum-soft.com/news/winter99/sparkgap.shtm > > > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .