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> Stalled, the train motor pulls 950 mA, while the stall current of the NXT motor
> is a whopping 2 Amps. So a single NXT motor output should easily handle a
Some precisions here:
- NXT stall current is 2A but only for a short time: internal thermal protection
will trip at a current much lower than that (exact value depends on temperature
and overload duration). A practical value is about 1A
- NXT motor driver itself limits the current around 1A too.
Philo
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In lugnet.lego, Philippe Hurbain wrote:
> A practical value is about 1A - NXT motor driver itself
> limits the current around 1A too.
Ah, thank you - so running two stalled train motors would exceed the NXT output,
but running one train motor up to a stall conditions should be fine. Out of
curiosity, along with the output limitations on the NXT (1 A) and RCX (500 mA),
does anyone have the output limitations (voltage and current) on the train
transformer?
--
Brian Davis
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In lugnet.lego, Brian Davis wrote:
> In lugnet.lego, Philippe Hurbain wrote:
>
> > A practical value is about 1A - NXT motor driver itself
> > limits the current around 1A too.
>
> Ah, thank you - so running two stalled train motors would exceed the NXT output,
> but running one train motor up to a stall conditions should be fine. Out of
> curiosity, along with the output limitations on the NXT (1 A) and RCX (500 mA),
> does anyone have the output limitations (voltage and current) on the train
> transformer?
The linear regulator inside is a 1.5A version if I remember well, but I may be
wrong. Cross posted to lugnet.trains trying to get train guru opinion...
Philo
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In lugnet.lego, Philippe Hurbain wrote:
> In lugnet.lego, Brian Davis wrote:
> > In lugnet.lego, Philippe Hurbain wrote:
> >
> > > A practical value is about 1A - NXT motor driver itself
> > > limits the current around 1A too.
> >
> > Ah, thank you - so running two stalled train motors would exceed the NXT output,
> > but running one train motor up to a stall conditions should be fine. Out of
> > curiosity, along with the output limitations on the NXT (1 A) and RCX (500 mA),
> > does anyone have the output limitations (voltage and current) on the train
> > transformer?
>
> The linear regulator inside is a 1.5A version if I remember well, but I may be
> wrong. Cross posted to lugnet.trains trying to get train guru opinion...
>
> Philo
At BayLTC we usually run four train motors on one loop using stock Controller
with a 1.2 amp wall wart.
Bruce
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In lugnet.lego, Philippe Hurbain wrote:
> In lugnet.lego, Brian Davis wrote:
> > In lugnet.lego, Philippe Hurbain wrote:
> >
> > > A practical value is about 1A - NXT motor driver itself
> > > limits the current around 1A too.
> >
> > Ah, thank you - so running two stalled train motors would exceed the NXT output,
> > but running one train motor up to a stall conditions should be fine. Out of
> > curiosity, along with the output limitations on the NXT (1 A) and RCX (500 mA),
> > does anyone have the output limitations (voltage and current) on the train
> > transformer?
>
> The linear regulator inside is a 1.5A version if I remember well, but I may be
> wrong. Cross posted to lugnet.trains trying to get train guru opinion...
The Australian LEGO wall wart is marked 10V @ 7VA on the secondary. I don't
recall all the stuff I learnt about the relationship between VA and W, but that
seems to me to indicate about 0.7A. I believe this generally reduces as load
increases, but again I don't recall all that stuff... Philo?
M>ltc uses a home-built 3A transformer for our displays.
ROSCO
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> The Australian LEGO wall wart is marked 10V @ 7VA on the secondary. I don't
> recall all the stuff I learnt about the relationship between VA and W, but that
> seems to me to indicate about 0.7A. I believe this generally reduces as load
> increases, but again I don't recall all that stuff... Philo?
You are right, the main limitation probably comes from wall wart... You are
essentially right for the 0.7A current (though it is not hard limit, rather a
safety one).
Philo
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