Graham Daniel wrote:

> Ben,
> use approx 4k7 pull down on the OSC1, ground the emitters of a NPN
> transistor, use a 10k pull down from the base to ground and also connect
> base to the pic via 470 ohm resistor

Graham,

Excellent! Thanks very much - I now have the PIC merrily switching
between the three required voltage levels (or hopefully near enough!).

I didn't have the exact resistor values you mentioned, and the only
transistors I have already have built-in 10K bias resistors (given my
level of electronic knowledge, this merely confuses me)... but I played
around with things based on what you suggested, and eventually arrived
at something that seems to work.

The SX chips should arrive tomorrow, so hopefully I'll find out if it
really does work fairly soon. Hopefully the software (something I'm a
little more familiar with :) should just work first time... (yeah
right).

Thanks again,

Ben