Re: (ET) Fine control

["Bob Murcek" <rmurcek geisinger edu>]

Bill,
There are a couple of ways to get finer control near zero.  Probably the 
cleanest would be to use a solid-state controller and use a potentiometer 
with a logarithmic taper for the speed control.  I think such a pot could 
be arranged mechanically so that there'd be less change in speed near 
zero.  I couldn't see any easy way to get single-lever speed and direction 
control using a pot, however.

Partly because of that problem and partly because I didn't want to do away 
with the neat microswitch mechanism anyway, I ended up using the 
microswitches to select different resistors to set the speed.  Using this 
method you could make the lower few speeds (There's a total of seven 
forward speed positions.) close together.

4QD sells inexpensive LED bar indicators for battery level.  I bought one 
but haven't tried it yet.  They're very basic, i.e., nine LEDs in three 
color groups mounted on a PC board.  Some kind of gussying up will be 
required.

>>> <wilbett earthlink net> 7/24/2002 3:11:37 PM >>>
    I've learned a lot from the solid state controls discussion initiated 
July
18. It looks like some variety of the 4QD may do the job, but now I've 
changed my
mind a little bit as to what I myself actually want.
    The present manual speed lever method, with its concentric cam ridges 
and
micro switches actually does a great job of speed changing at high 
efficiency
(though I wish they had put rollers on the micro switch arms, so they 
could start
up the cam ramps easier).  But near the neutral area, the 1A switch is 
either
open or closed, nothing in between. What  I think we would like, on my E12 
or
your E20, is incremental speed control right around zero, both forward and
reverse. I realized this last evening while mowing grass. When moving 
forward to
mow up close to a down spout, for example, without lungeing and smashing 
things,
we need finer control than is now possible in the higher gears. If I'm 
mowing the
yard in D2, I don't what to take the time to shift gears to LL to get this 
fine
control. I may want to go slowly forward and back several times, and then 
would
not want to have to shift back to D2 to continue zooming across the yard.
    It looks like the fixed resistor R1 (in the E12) could be replaced with
something smoothly variable (solid state?) and non linear so that very fine
tractor movement around zero can be obtained (isn't this what a hydrostatic
coupler does on the big tractors?). With the transmission in D1 or  D2,  it
would, however, have to be able to handle the high current demand. How can 
this
be accomplished?
    I still want the LCD analog battery voltage bars. Where can you get 
those?
Lets roll.

Thanks, Bill Alburty