Subject:
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Re: Electrical Things (was: Railroad Dilemma)
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Newsgroups:
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lugnet.trains
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Date:
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Mon, 8 Mar 1999 16:52:06 GMT
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Viewed:
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4635 times
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Simon Robinson writes:
> I finally got round to having a play with my controllers and my
> multimeter.
>
> PUTTING TWO CONTROLLERS ON THE SAME TRACK
> -----------------------------------------
> Firstly, apologies to Ben, who suggested if you connect two
> controllers to the same track, then they'd short only if the
> controllers had opposite polarities. Ben was actually correct.
>
> What I actually found was the voltage on the track is the BIGGER
> of the two voltages that the two controllers puts out, if they
> have the same polarity. If they have opposite polarities, then they
> always short out and there's a small residual voltage (about 0.3V)
> on the track. I'm a bit puzzled as to what can be going on in
> the controllers to cause this behaviour.
That is because there is a diode to protect from reverse voltage and the
voltage drop is about 0.3V
>
> Incidently there doesn't seem to be any effect on the speed the train
> goes at if you put an extra controller on the track. (I wondered if
> there might have been because the controllers could supply more current)
>
> CHARACTERISTICS OF ONE CONTROLLER
> ---------------------------------
> As I suspected the controller supplies a variable voltage. As you move the
> speed regulater from zero to the first of the 6 marks the voltage suddenly
> jumps up to about 3V. It then increases linearly up to about 9V for the
> maximum speed. I say roughly because my controllers, both newish, differ
> by 0.2V, so I guess Lego's quality control for this stuff isn't too exact (it
> doesn't really need to be).
>
> The motor power unit has a resistance of 8.7 ohms, so at max. speed, it's
> eating up about an amp. (or about 9 watts of power).
The maximum current is about 0.7A MAXIMUM ( maximum voltage and whell not
turning) with one controller
> In more detail, for one of my controllers, the readings were
>
> open circuit voltage with which means
> voltage train running internal resistance is
> Full power 9.24V 9.04V 0.09ohms
> Minimum speed 3.04V 2.99V 0.02ohms
>
> I'm surprised that the internal resistance varies with voltage. I guess
> I'll have to go and read up on my basic electronics again to figure out
> what's going on.
the internal resistance will vary with voltage apply ( or will look to) because
at full speed the voltage is not realy constant there is a little variation
(ripple) du to the voltage regulator (the box you plug into the wall) that
is near is maximum capacity, and because there is a semiconductor voltage
regulator inside the controller.
> Simon
> http://www.SimonRobinson.com
<snip>
if there is two controller, then you will be able to draw about twice the
current of a single controller or about 1.4A
Martin
Electronic technitian
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Message is in Reply To:
 | | Electrical Things (was: Railroad Dilemma)
|
| I finally got round to having a play with my controllers and my multimeter. PUTTING TWO CONTROLLERS ON THE SAME TRACK ---...--- Firstly, apologies to Ben, who suggested if you connect two controllers to the same track, then they'd short only if the (...) (28 years ago, 8-Mar-99, to lugnet.trains)
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