Special ICs, such as the Fairchild 74ACT715 (formerly National LM1882) and the Philips SAA1001, have been developed for generating video synchronisation signals. However, the annoying thing about such ICs is that they are often difficult to obtain. On top of that, there are other problems, such as that the one has to be initialised by a processor and the other is difficult to synchronise to an external signal or ends up being incorrectly synchronised. However, it is also possible to use a ‘discrete’ circuit to generate the video sync signal for a project such as a homemade test pattern generator.