On Wed, 31 Oct 2001 17:48:28 +0100
=?iso-8859-1?Q?Verner_Tops=F8e-Jensen_OZ5TG?= <oz5tg@post2.tele.dk>
writes:
>
>I am trying to build a controlcircuit for a major PA with an YC156.
>I am using a pair of Jennings 10-1000PF motordriven capacitors.
>
>Problem :
>The integrated DC-motors requires 18volt to work reliably, but the
>end-to-endtravel takes only about 3 seconds i.e. 330PF/sec.
>The controlcircuit has a delay at about 25mSec i.e. the cap. stops
>8 - 10 PF off the wanted value. No problem on 160, but on 10, it
>is a matter of success or failure.
>
>The controlcircuit using variable resistors, cannot, even with a very
>little
>hysteresis, stop the motors without overshoot.
>
>I have tried to chop the DC for the motors. That was an improvement,
>but far from enough.
>
>Any ideas about how to slow down the RPM and maintain the torque ?
>
>I checked the Jennings URL, but they do not have any information about
>
>how to do.
>
>
>Any help, any idea is welcome.
>
>
>OZ5TG, Verner
>
Hi Verner,
When you tried PWM did you include a catch diode(s) across the drive?
PWM is the best you are going to do without building a real servo
system, including velocity feedback, which will allow for the slow RPM &
hi torque you're seeking.
Velocity feedback can come either from a tach connected to motor shaft
or if that is not easily implemented by calculating the motor speed from
the voltage & current seen at the motor terminals.
Take a look at the National LMD18200 data sheet -- perhaps on line at:
www.national.com
73 & Good evening (by you),
Marv WC6W
*
________________________________________________________________
GET INTERNET ACCESS FROM JUNO!
Juno offers FREE or PREMIUM Internet access for less!
Join Juno today! For your FREE software, visit:
http://dl.www.juno.com/get/web/.
--
FAQ on WWW: http://www.contesting.com/FAQ/amps
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
|