Hi - I have a circuit which uses a NE555 & a CD4017B to drive a lot of LED's (through 2N3053's) in a running message display. The circuit requires 9V. - my question is, I'm planning on using a plug-in AC to DC unregulated wall adaptor and a LM7809. Do I need a filter cap across the LM between the output & Gnd. & if so, what value? Also, is a 12V wall adaptor ok? Thanks for your help!