I'm a first time easyeda user wanting to simulate a buck converter circuit. I've constructed the circuit below [https://easyeda\.com/editor\#id=\|aa8c91107b1f45b49f903fce40abef82](https://easyeda.com/editor#id=%7Caa8c91107b1f45b49f903fce40abef82) When simulating I get the following: > Circuit: gooduntitled > > Doing analysis at TEMP = 27.000000 and TNOM = 27.000000 > > Warning: r9: resistance to low, set to 1 mOhm > Warning: singular matrix:  check nodes u3\_3 and u3\_3 > > Note: Starting dynamic gmin stepping > Note: One successful gmin step > Note: One successful gmin step > Note: One successful gmin step > Note: One successful gmin step > Note: One successful gmin step > Note: One successful gmin step > Note: One successful gmin step > Note: One successful gmin step > Note: One successful gmin step > Note: One successful gmin step > Note: One successful gmin step > Warning: singular matrix:  check nodes u3\_3 and u3\_3 > > Warning: Dynamic gmin stepping failed > Note: Starting source stepping > Warning: singular matrix:  check nodes u3\_3 and u3\_3 > > Note: One successful gmin step > Note: One successful gmin step > Note: One successful gmin step > Note: One successful gmin step > Note: One successful gmin step > Note: One successful gmin step > Note: One successful gmin step > Note: One successful gmin step > Note: One successful gmin step > Note: One successful gmin step > Note: One successful gmin step > Note: One successful source step > Warning: singular matrix:  check nodes u3\_3 and u3\_3 > > Warning: singular matrix:  check nodes u3\_3 and u3\_3 > > Warning: source stepping failed > > Transient solution failed - > > Last Node Voltages > \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\- > > Node                                   Last Voltage        Previous Iter > \-\-\-\-                                   \-\-\-\-\-\-\-\-\-\-\-\-        \-\-\-\-\-\-\-\-\-\-\-\-\- > u3_2                                              0                    0 > u3_6                                              0                    0 > volprobe                                          0                    0 > u3_1                                              0                    0 > gnd                                               0                    0 > u3_3                                              0                    0 > l2#branch                                         0                    0 > v1#branch                                         0                    0 doAnalyses: iteration limit reached > tran simulation(s) aborted > Error(parse.c--checkvalid): volprobe: no such vector. > ngspice-26 done I used the design manager to check connections and node connections. I can't spot anything wrong so I am uncertain as to how to fix this error? Is it possible that the LM2678 switching ic used here does not have a spice model available for simulation? Any help would be greatly appreciated.