Thanks for your query on Transformers. It made me think about including a transformer model in Oscad which, unfortunately, was missing in the earlier version of Oscad. With this, you can now simulate your transformer circuit.
Do the following:
<ol><li>I have attached a file KiCadtoNgspice.py. (<a href="http://www.oscad.in/data/KicadtoNgspice.py" target="_blank">http://www.oscad.in/data/<wbr></wbr>KicadtoNgspice.py</a>) Please copy this file in the folder kicadtoNgspice (You can find this folder inside the main OSCAD folder). You can make a backup of the KiCadtoNgspice.py already existing in this folder.
</li><li>Once you are done with this, create your schematic using the component "transfo" under the "device" library in the schematic editor. Change its reference to U. (It originally has a reference T). To change the reference, right click on it and choose Edit Component--> Reference.
</li><li>Now proceed with the usual Analysis Insertion and Netlist Conversion</li><li>In the Netlist conversion, it asks for the parameters of the transformer. You need to give the number of turns in the primary, secondary and the values for B-H table. If you do not input anything, it takes default values. These parameters are required as I have used the inductor couple-magnetic core model for transformer. To know more about this, I suggest you read the Ngspice manual attached (pg Nos.170 to 174) (http://ngspice.sourceforge.net/docs/ngspice-manual.pdf)</li><li>After inputting the parameters, you can simulate the circuit.</li></ol> I have attached an example project that simulates a step-up transformer. (<a href="http://www.oscad.in/data/Transformer.abc" target="_blank">http://www.oscad.in/data/<wbr></wbr>Transformer.abc</a>) This will help you get started. In the example project, primary turns = 310, secondary turns = 620, so the turns ratio is 1:2. You can see that the ratio of input to output voltage is also 1:2.

Please rename the file Transformer.abc to Transformer.zip and use.