Cheers Richard (I will, and Im clearly rubbing off on people!)

Im not sure if Id got the wrong end of the stick originally, or persuaded myself since - I thought the pulse width encoding only went as far as the receiver, and the speed controller worked purely as a step-up/mixer. I guess keeping things encoded longer is a bit more fail safe. Im not sure whether it helps or hinders my cunning plans for microcontrollers - lose an A/DC, gain an interrupt driven timing loop. Meh. Does this mean speed controllers also only have about 16 levels of gradation per channel, or are they completely analogue? (16 is a figure I think Ive seen for transceiver granularity, but I dont know how universal it is - it seems a bit coarse for the effects a gyro could have).

I guess Id presumed that the speed controller took all its input channels on independent wires, whereas the signal can be de-multiplexed internally this way.

Not that it helps with some of my dafter ideas (so many channels, so few speed controllers... *here* MOSFET MOSFET MOSFET) but youve deconfused me a lot, so thank you. :-)

Presumably if Im trying to get a reading out of a gyro (without hooking it to the receiver), this means I need to feed a neutral pulse into it?

I think my talk of channels regarding the gyro was a bit ambiguous - I wasnt talking R/C channels (at least, directly), I meant that I wondered if a radio controlled helicopter gyro would give a separate output for each axis of rotation (roll, pitch, yaw). What youd do with them on a ground-based robot is another matter, but I just wondered if they were there.

As for the number of channels I need: for my first robot, not many (Im occasionally practical - two analogue, two digital will be fine). As for interesting designs... my most effective (predicted) design has six (possibly seven) analogue and at least four (probably many more) transmitted digital channels; there are sixteen analogue outputs from the control system and at least twenty digital ones. Not counting telemetry. Youll know it when you see it (but not for a year or two)! Theres a reason Im leaning towards digital control. :-) (Oh, and its slightly more practical than it sounds.)

Thanks again for the help, and sorry to slightly subvert the subject (although Im nearer to on-topic than I usually manage when I do this!)

--
Fluppet
(Worryingly, *not* one of my longer posts.)