Thank you everyone for viewing my inquire.
I was thinking the other day while driving about using a dual power supply that would output 5v and 3.3v. now I use decoupling caps on both the vdd in and the dual vdd out but can someone tell me if I need to use decoupling caps on my vdd, gnd for ic like microcontrollers etc that are on the regulated side of the volt regulater as the volt reg has been decoupled? I was not sure if, that it is regulated already, you should not see the spikes you would see on the mains vdd input and not need the extra caps.
Thanks for your help.

 

Lets just call it a Yes/probably... In general its always best to decouple as close to the micros supply input as possible.. depending on where the regulator is in relation to the micro..

 

Thank you everyone for viewing my inquire.
I was thinking the other day while driving about using a dual power supply that would output 5v and 3.3v. now I use decoupling caps on both the vdd in and the dual vdd out but can someone tell me if I need to use decoupling caps on my vdd, gnd for ic like microcontrollers etc that are on the regulated side of the volt regulater as the volt reg has been decoupled? I was not sure if, that it is regulated already, you should not see the spikes you would see on the mains vdd input and not need the extra caps.
Thanks for your help.

The ICs themselves create noise on the Vdd line due to the inductance in the trace from the regulator to the IC. So it is a good idea.

 

The rule of thumb about decoupling capacitors is almost as iron-clad as Ohm's Law. At least one capacitor at every device power pin, as close as possible, all the time, every time.

ak