Subject:
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Re: 9v Gear Motors
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Newsgroups:
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lugnet.robotics
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Date:
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Thu, 8 Jun 2000 22:19:01 GMT
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Viewed:
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681 times
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The motors are DC motors, with two terminals. A DC motor will reverse direction
if the current direction is reversed. If the circuit to the motor coils are
left open, no magnetic field is produced and the motor has no resistance to
turn, so there is no brake, and if the coil circuit is closed, with no power
applied, the coils will resist the motor from turning because as soon as the
motor turns the coils produce a reversing magnetic field.
I could be totally off on the braking action, but I am sure about the direction
reversing.
The pulsing of the current to vary motor power is controlled by the RCX itself.
It is not part of NQC. The firmware/hardware has this control as part of its
standard features.
-Wes
Jerry Kalpin wrote:
>
> I have been searching lugnet for more info on the standard Lego 9v
> gearmotors. I know there are 4 terminals. I know there is forward, reverse,
> off (with braking) and float (without).
>
> Mark Overmar's NQC tutorial which is included with Dave Baum's book/CD has a
> scheme to vary the speed by turning it off and on many times a second. I
> absolutely do not understand the code, but it works anyway! He says: "It
> constantly checks the variable speed to see what the current speed is." But
> is there speed monitoring, or current monitoring, or even something that would
> tell the RCX motor direction?
>
> If anyone knows how the motor works, or has any good links, let me know.
>
> Thanks, Jerry
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Message is in Reply To:
 | | 9v Gear Motors
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| I have been searching lugnet for more info on the standard Lego 9v gearmotors. I know there are 4 terminals. I know there is forward, reverse, off (with braking) and float (without). Mark Overmar's NQC tutorial which is included with Dave Baum's (...) (24 years ago, 8-Jun-00, to lugnet.robotics)
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