Subject:
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Re: More juice out of the standard motors.
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Newsgroups:
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lugnet.robotics
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Date:
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Thu, 22 Mar 2001 04:42:13 GMT
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Viewed:
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702 times
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On Wed, 14 Mar 2001 21:44:19 GMT, "Tom Trentham" <Tom@Trentham.com>
wrote:
> How much voltage can you put across the Lego geared motor ( >9V) before it
> breaks?
>
> How much more power/torque can you gain by putting more voltage through?
>
> Is this a good/sensible idea?
>
> Who has done this? Why? How? etc.
>
> Tom.
The day I got my RCX2.0, I took it apart and confirmed my suspicion
that the motor drivers used in the 1.0 are similar to a Melexis
MLX10204. A similar chip is used in the 1.0, but the Melexis chip is
used in the 2.0. I then fired off an e-mail to Melexis requesting a
data sheet on this part so I could find out what it's limitation are.
I haven't heard back from them. It's time to try again....
Anyway. in general, for short sprints you can overdrive most motors
well beyond their normal specifications. A build up of heat within the
motor is what breaks down the insulation on the windings and kills it,
but there is a significant amount of thermal capacity in a motor, so
you get at least a couple of seconds to overdrive it before the core
temperature rises to the point of melting the insulation. This is not
the case for the motor drive circuits. The IC's that drive the motor
will die before the motor does, so the real limiting factor will be
the performance limits of the drive circuit. Of course, you could use
an external transistor to power the motors directly and take the
stress off the drive circuit, in which case you'd be looking at an
external power supply anyway, so you could add as many batteries as
needed to achieve the desired power output, but again, you'd have to
keep it short.
BTW, there is one other limit on a motor that I'm aware of, and that's
the point where the magnetic field within the windings saturates. I
have no idea what it takes to do that or whether this limit would be
reached before you burned out the motor but I seriously doubt it.
Matthias Jetleb
VA3-MWJ
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Message is in Reply To:
 | | Re: More juice out of the standard motors.
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| (...) It could be that I am misinterpreting it, but the original post seemed to ask the question "How do you get more power out of the Lego motors?" It was not about gearing or rotation sensors at all. These things are important but the implication (...) (24 years ago, 14-Mar-01, to lugnet.robotics)
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