On Tue, 4 Jan 2000, Des Bromilow wrote: > different. Even the simplest things such as the typical inputs to a > servo are unknown to me. This was discussed on this list (I think) in the past week or two. Check the archives at http://www.piclist.com R/C servos use Pulse Width Modulation. Typically 5V in, 1-2 msec period, 50msec rate. 1.5 msec is typically center position of the servo. I found that the rate is not terribly important. 20 ms IPI made mine respond more quickly since the position error was updated more frequently. Pulse width jitter of 2 usec would cause my servos (Futaba) to buzz as they tried to track the minute errors so be sure to have consistant pulse widths (unless you like warming them up). And an earlier poster asked why we continue to use such a primative means for R/C control. Because it works, is highly noise immune, and entrenchment. This stuff was designed back in the 60's when tubes were still used. You might just as well as why we still used odd-ball baud rates like 9600, 19.2k, 14.4k, 28.8k etc when we could switch to nice round numbers that divide easily from our standard crystals (like the 31.25K baud of MIDI ). Why does America still insist on using inches, feet and miles when most of the rest of the world uses metric measures? You don't suppose that the Mars Climate Orbiter would have succeeded if there wasn't that little metric/english mixup? All serious science uses metric measures. Why can't the civilians learn it and save the headaches of constant conversion and errors? I grew up with imperial measure, but we switched to metric 30 years ago and we're doing just fine. Must have something to do with the French television system SECAM. Something Essentially Contrary to American Method . Robert --Robert.Rolf@UAlberta.ca "If 'debugging' is the process of removing errors, then 'programming' must be the process of putting them in".