Steve,
If you need a linear frequency response from an RC network look up op-
amp integrators.
Bernard
--- In mach1mach2cnc@..., Steve Blackmore <steve@p...>
wrote:
On Sun, 10 Aug 2003 05:21:34 -0700 (PDT), you wrote:
I have hardware that will provide you with 0 to +10VDC and the
resolution is extremely accurate. If you were to configure Mach2 at
45kHz with the PWM at 45Hz and the MAX RPM for the Pulley Ratio set
at 1000 you would get +.001VDC per 1 revolution. The hardware that I
offer has a low offset that will allow the voltage scale to start
from 0 along an adjustable high gain that will provide up to and
including +20VDC, +10VDC being in that range. The hardware requires a
+24VDC isolated power supply along with filtering of the PWM voltage
through an RC circuit prior to input. I will up load a photo of the
hardware, title will be analog amplifier.
Thanks, but I've already thrown enough money at this problem. There
are people using step/dir or PWM, I'd just like to know how they did
it. 45Khz is out of the question, without buying yet another
computer!
I can get very even resultion by fooling Mach2 that my top speed is
higher than I want and forgetting speeds below 100rpm. There must
be
a better way though. The problem is that as op amps get close to
rail
values they cease to function very well, but you just gave me a nice
clue by mentioning 24V. If I increase my input voltage some more
(12V
currently), I can set top and bottom end to work at other than 10 &
0V
and just use the linear bit in the middle ;)
What values are you using for RC circuit?
The only reason I started playing with PWM is the problem RC7.2 has
with step/dir. Perhaps Art's next offering will fix it?
--
Steve Blackmore
