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 Robotics / 10623
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Subject: 
RE: Drive R/C Servos with the RCX and pbForth (long)
Newsgroups: 
lugnet.robotics, lugnet.robotics.rcx.pbforth, lugnet.robotics.rcx
Date: 
Sat, 12 Feb 2000 13:06:17 GMT
Viewed: 
5675 times
  
> > In lugnet.robotics, Ralph Hempel writes:
> > > Well, after a few hours of crunching away at the problem, I
> > > now have pbForth code to allow you to control and hold a servo
> > > in up to 100 positions.

Then Ben Jackson wrote:

> > If you're using a custom motor driver in pbForth, why use the inverter circuit
> > at all?  Why not just generate the desired waveform directly?  Is there not
> > enough current to drive the servo that way?
> 
> No, the servo needs power to the + and ground terminals to drive
> the motor to the setpoint indicated by the signal wire. If I don't
> invert the signal there is no power for about 30msec and only
> 1 or 2 msec ov voltage on the motor port.

I should add here that no external power source is necessary to drive
the servo. This is important since a micro or miniservo and an SMT
version of the driver can be made to fit INSIDE a space similar to
a worm gear box (6588 in LDraw).

I'm looking for packaging ideas that will allow a few different
mounting options for the servos. Three different options are
needed:

1. Servo shaft comes out the top of a brick
2. Servo shaft comes out the bottom of a brick
3. Servo shaft comes out the side of a brick

I think that using Technic beams or even half-beams (look out for
Cyberslam on clearnace) will give the best mounting.

Cheers,

Ralph Hempel - P.Eng

--------------------------------------------------------
Check out pbFORTH for LEGO Mindstorms at:
<http://www.hempeldesigngroup.com/lego/pbFORTH>
--------------------------------------------------------
Reply to:      rhempel at bmts dot com
--------------------------------------------------------



Message is in Reply To:
  RE: Drive R/C Servos with the RCX and pbForth (long)
 
(...) No, the servo needs power to the + and ground terminals to drive the motor to the setpoint indicated by the signal wire. If I don't invert the signal there is no power for about 30msec and only 1 or 2 msec ov voltage on the motor port. By (...) (27 years ago, 12-Feb-00, to lugnet.robotics, lugnet.robotics.rcx.pbforth, lugnet.robotics.rcx)

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