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 Robotics / Handy Board / 6936
6935  |  6937
Subject: 
Re: Handyboard low voltage motor control
Newsgroups: 
lugnet.robotics.handyboard
Date: 
Wed, 20 Oct 1999 19:17:48 GMT
Viewed: 
817 times
  
Well, I went with separate h-bridge to maintain PWM and it turns out that
even though the motors are geared down, they still don't have enough torque
to haul around all the batteries. Looks like I'll stick with 9v motors...

Thanks for the suggestions,
Paul


Gary Livick wrote in message <380B772F.FADA385C@pacbell.net>...
Good point...

There is another way.  You can build your own h-bridges using mechanical
relays and maybe a few diodes.  They drop zero volts, which is good. • However,
you obviously can't PWM the things.  If you just want rudimentary speed
control, you could add another SPDT relay in line to add a dropping • resistor
in series.....  You can use the motor outputs right off the Handy Board to
switch your bridges.

If you want PWM, you can build your h-bridges from solid state dc-dc • relays.
They switch in about a half microsecond, so are plenty fast.  Some even • have
flyback diodes built in, and only turn on when forward biased, which is • great
for use in h-bridges.  However, these will drop some voltage, so you have • to
account for it when sizing your motor voltage supply.  To control these, • you
also use the outputs directly off your Handy Board.  I've used the latter
method myself, and it works great.

Gary Livick






Message is in Reply To:
  Re: Handyboard low voltage motor control
 
Good point... There is another way. You can build your own h-bridges using mechanical relays and maybe a few diodes. They drop zero volts, which is good. However, you obviously can't PWM the things. If you just want rudimentary speed control, you (...) (25 years ago, 18-Oct-99, to lugnet.robotics.handyboard)

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