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Subject: 
Re: technic motors as generators????
Newsgroups: 
lugnet.technic
Date: 
Thu, 5 Oct 2000 02:30:47 GMT
Viewed: 
996 times
  
These motors, used in Mindstorms, have 3 programmed states:  On, Off and
Float.  When 'On' the motor runs at the set power level.  When 'Floated' the
motor coasts to a stop (power removed).  When 'Off' the motor brakes to a
stop.  This braking is quite good and you can have it On for (say) 1/100 sec
and Off for 1/100 sec, providing an effective speed control that is better
than Pulse Wave Modulation.  This braking is done by short-circuiting the
motor.  Try it by attaching a short lead to the motor and reconnecting it back
in short-circuit mode (no battery power!).  The motor will be much harder to
turn.  When you do turn it a counter emf is created driving the shaft in the
opposite direction.

The battery box (with switches) that comes with the auxiliary motor kit gives
you all three motor states:  On when you push the button down hard, Off when
you release the button completely and Float when you don't quite release it.

In fact, these motors are very fancy little devices!

Jerry

In lugnet.technic, Ross Crawford writes:

Brad Hamilton <bhamilto1@home.com> wrote in message
news:G1vvuq.9no@lugnet.com...
I saw some sort of diagram some place (I think in some sort of Dacta
documentation) stating that you could use a technic motor as a generator.

This makes sense, but I never tried it until today and I am utterly amazed
at how well it works!

I'm using the 2x2 motors that come in the Mindstorms set.  I hook two of
these together (without any power source), and hook up a gear to each. • Even
if I turn one motor the most minor amount, the other motor turns in
lock-step.  When I turn one motor one turn, the other one turns exactly • the
same amount!

I've never heard of a generator that was is so efficient!

Will this damage my motor??

I tried the same trick, but hooked up a micro-motor as the secondary.  It
turned as well, although at a much slower rate.

I also tried hooking up the "generator" to my aquazone train.  I had to
crank it up quite a bit to get the train to move, but I got it going at a
good clip using just my wrist power alone!

The only down side seems to be the limited load that the secondary motor • can
handle.  If I put even a moderate load on it, then it won't turn unless I
crank the other motor harder (presumably providing more voltage).


Basically motors & generators are pretty much interchangeable. You'll find
that if you gear the "generator" up to a higher speed (5:1 is good), it'll
be harder to turn, but you wont have to crank as fast. Also, if there's a
big load on the "motor", the "generator" will get harder to turn.

Regards,

ROSCO



Message is in Reply To:
  Re: technic motors as generators????
 
Brad Hamilton <bhamilto1@home.com> wrote in message news:G1vvuq.9no@lugnet.com... (...) Even (...) the (...) can (...) Basically motors & generators are pretty much interchangeable. You'll find that if you gear the "generator" up to a higher speed (...) (24 years ago, 4-Oct-00, to lugnet.technic)

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