Checking your circuit; https://easyeda.com/joaoff/teste-nNK6AaGAS You appear to have selected the LM7812CT symbol then pressed the `I` Hotkey and set the spice prefix to `X` to ensure that the symbol is expecting to be associated with a subckt spice model. However, you have not pasted a spice model into the schematic so, unless you have pasted in a spice model into the symbol (see below) or the model is already in the EasyEDA library, then EasyEDA will not netlist a subckt into the spice netlist for the schematic. * The simplest way to fix this is to paste a copy of the netlist into the schematic (see my reply to: https://easyeda.com/forum/topic/Attaching_a_subckt_to_a_symbol-Hz4mgysK2) * Alternatively, please make your own local copy of the LM7812CT symbol and then do: **Super Menu > Miscellaneous > Edit Subckt...** * Or, why not just use the ready made LM7812EE from the `Regulator` section of the `EasyEDA Libs`? * If you look at the netlist you will see that the capacitors do not have values: the last field of the spice line for each cap is empty. This is because you have put part numbers and not values into the value fields for the capacitors. Spice cannot extract a value from a part number. You must enter explicit values.must have values. Without values, your circuit will not simulate. * To understand how to do simulation in EasyEDA, please see: https://docs.google.com/document/u/1/d/1OWZVVFRAe_2NW3WratpkA_SGuHa5AcRow5ZRfvcoVTU/pub (The Google link above are to the original copy of the Simulation eBook which you can also find at: https://easyeda.com/Doc/Simulation-eBook/ but the table of contents in the EasyEDA copy is broken and misses out some sections. We are working to fix it but in the meanwhile the copy published to the web from Google Drive works just as well.)

Please note that: 1. You will need a subckt for the LM7912CT (Hint: use the LM7912EE from the EasyEDA Libs); 2. You regulators are back to front: OUT and IN are reversed. :)

Hi, Andy! Thanks for the explanation! The LM7912CT was not appearing in the netlist because its prefix was "U". When I changed it to "X" it appeared. With your help in the other post, I managed to paste the models into the canvas. I am a little confused about the library components. Each library component can have a schematic symbol, a footprint and a spice model? If that's right, can't the component have more than one model or footprint? or should I create a new component just to insert a new model and/or footprint (this seems bad to me)? I do not understand the reason why the capacitors do not have a value associated. I choose the capacitors from the library based on their part number. Technically, the part number says capacitor value, tolerance, etc. So, I expected that all this information would be associated with the library element. Yet, the "Part Attributes" say "Name" and not "Value". I would never imagine that I should enter the capacitor value in a "Name" field. Even inserting the capacitance values in the "Name" field of the "Part Attributes" the values are not netlisted. The battery component has a "Voltage[V]" field in the "Custom Attributes" that I set to the voltage I wanted, but the capacitor does not have a "Value" field in its "Custom Attributes". Please, perceive that the pins 1 and 2 of LM7912CT are swapped compared to the LM7812CT, so I swapped pins 1 and 2 in the LM7912CT model (the model can be obtained in http://ltwiki.org/files/LTspiceIV/lib/sub/regulators.lib or https://github.com/ssfrr/proxlamp/blob/master/sim/lm79xx.lib). I copied the generated netlist to the ngspice online, added the missing capacitor values and simulate, obtaining the expected result. Regulators inputs and outputs are not reversed. LM7812CT receives 17 V and should output 12 V. LM7912CT receives -17 V and should deliver -12 V. Obs: parameters M, VTOTC and BTATCE of the JFET in LM7912CT model does not exist in the NGSpice JFET model and are ignored by the simulator. A warning message is issued. Thanks again!