--- In [email protected], "richmogd" <[EMAIL PROTECTED]> wrote:
> > Thanks for the suggestions. There are a couple of reasons for the two > boards: > > - The top board will be mounted on spacers just below the container > lid. This board will contain main logic/control circuitry as well as > LEDs - I need these to be just below the casing. > - The bottom board contains power supply and external interface > circuitry, opto isolation, relays etc. That's the sort of thing I thought you were doing, and I would re-iterate that I would do a single scheme/netlist and layout the two boards side by side, it is so much easier to move components from one board to another (for example, the resistors driving the LEDS of the optos could be on either side, as could relay driver circuits). Also, assuming you will ordering equal quantities of boards then you will probably want to panel them side by side for production anyway (generally speaking on small/prototype production one big board is cheaper than two halfs, and some places will do the extra routing as well, but you can always use a bandsaw!). BTW, don't worry about noise from the power side going up to the control if the circuit is isolated (unless your cct is very poor!). Ferrite beads are used to stop HF signals from the control section propogating out and using the power circuits as arials, they are only effective from about 10MHz up (CE and FCC regulations measure for radio signals in a band that starts at 20MHz).
