Found Collection

Just bought two brand new Proto 1000 F3's.  Ran into the following
operating issue and I wonder who has solved the problem......?

If I run the both units cab forward they ae perfectly matched in
running speed and run very quietly.  Similarly both units running
backwards run perfectly.

However if I couple both units back to back (one cab in each direction)
they run but the unit with the cab facing the direction of travel is
pushed by the following unit -- so much so that the wheels on the lead
unit skid slightly on the track producing significant operating noise.

Since the couplers do not conduct electricity I have concluded (perhaps
incorrectly) that this problem is caused by the directional lighting
system.  It's "on" in one unit but "off" in the other when the two
units are coupled back to back.  I think the current taken by the light
in the unit that is on is making that unit run slower than the
following unit with its light "off".

Has anyone else noticed this and if so what have you done to remedy the
problem.  I'd like to keep the directional lighting functional.  Is
there a resistor or a light bulb or something we can add to the circuit
to make the units equivalent in each direction.....?

Please post resposne to this group or directly to:

with my thanks in advance.

PS: Is there an email address at Life-Like that I could contact?

Locos that have constant/directional lighting often have a set of diodes in
series with the motor.  These diodes cause a voltage drop, and the drop is
used to drive constant brightness bulbs.  This means that, if they are
connected to provide a bright headlight forward, but no light going
backwards, the motor loses about 1.2 volts in the forward direction compared
to the reverse.  So of course, the one running in reverse will run faster
than the one running forward.

It's possible to design circuitry that doesn't have this problem, and many
builders use it, but the diodes in series with the motor are dirt cheap and
simple to wire, and that's what we're stuck with.

Trace the wires to the motor and to the trucks.  You should find a circuit
board or just a diode or so between one side of the motor and one side of
the rail/ truck wiring.  If the headlights aren't important, remove the
diodes or just place a jumper around them.  If they are important, add
another set of diodes in parallel to the first, but oriented in reverse.
This will slow the engine down the same in both directions.  In order to get
any random selection of engines to run together you'll need to add a set of
diodes in series with every motor, but diodes are cheap- a few bucks will
buy hundreds from the surplus electronics places.  Diodes in the 1n4000
family work well and are common.

Fred Dabney, watching the action from BNSF MP 1112, El Paso sub.

--
Dave

 It's all an illusion!    (Henning)

...everytime i run the train around and around, i think of the
hamster...

...the trains are alive, you know...

...big john...   :))

--
Dave

 It's all an illusion!    (Henning)

...big john...   :))

This is a good point except, as I've said before I have built a few
directional lighting sets using Mark Rollins' diagrams. They use the same
diode matrix as in the P2K units I've seen, except I have a light for both the
foward and reverse directions. After installing these in Athearn units I have
experienced the same effect of the rear unit starting before the leading one.
There is no loss of 1.2V as you descrided above so what could be causing this
problem?

I've had all manner of locomotives, steam and diesel that simply ran better
in one direction than the other.  It /can/ be a matter of the worm shaft
binding as the slack runs out in the worm/spur interface, and if so often
thrust bearings can help.  I had one which drove me nuts until I found that
the motor itself was the culprit- it ran faster in one direction.  ????  I
did have one where it didn't even run at all in one direction, but that was
simple.  It had picked up a stray spike which was clinging to the magnet,
ratcheting on the armature.  One way, no problme.  Other way, instant lock.

If thrust washers are needed, NWSL has them in many sizes and incude both
SAE and Metric sizes.  They seem to be bearing bronze and are precision
parts.

As long as we're on the topic of diodes, though, let's consider the most
basic approach.  Take a standard bulb, place one end on the most convinient
ground, place the other lead on one end of a diode, and the other end of the
diode to the motor's "hot" brush.  The bulb will light when the motor is
running in one direction, not the other.   If for your purposes, the bulb
lights in the wrong direction, just reverse the diode.  But the bulb's
brightness will track the motor's speed- it won't be a constant brightness.

So, next we take into consideration one of intrinsic characteristics of a
semi-conductor junction:  It is not a dead short, but rather it is a very
high resistance in one direction of electron flow, and a low but finite
resistance to opposite electron flow.  Therefore, when a current is passed
through the diode in what is called the "forward" direction, there is a
small voltage developed across the junction.  The exact voltage depends on
the nature of the semiconductor, but for most common silicon diodes it runs
about .6 volts.  This voltage remains constant across a fairly wide ranges
of applied voltage to the diode as a whole.

So, if you place that same diode between the engine frame, and the other end
to the brush that used to be connected to ground, you can now place a small
bulb across the diode.  The motor current will pass through the diode, and
also through the bulb, lighting it.  As soon as you try to reverse the
motor, the voltage drop across the diode goes to the full applied track
voltage, and your little, low voltage bulb will pop.  NOt terribly useful,
and the small bulbs are normally rated at 1.2- 1.5 volts while you're only
providing them with .6 volts.  They'll be pretty dim.

NOw is where the wiring gets a bit complex.  First, take a pair of diodes.
Wire them with the little band on one end attached to the diode with the
band away from the first.  When you pass current through this pair, in the
forward direction the voltage drop is a nice, useful 1.2 volts.  But we
still have the one-way only problem.  So, take another pair of diodes wired
the same way as the first, but then connect them in reverse to the first
pair.  At one end, you have leads going to /two/ diodes, one to the band,
the other the end away from the band.  Each of the first diodes connects to
the other in each pair as above, then the leads at the other ends come
together again and connect to the opposite side of the power distribution
system.

By playing with the makeup of these diodes, leaving one off or adding more
you can get headlights that brighten in one direction and go off in the
other, or just go dim in the other.  But for a simple, constant brightness
in both directions setup, you can use just a simple plastic encapsulated
diode "bridge" from Rat Shack or whomever.  Run one of the leads intended to
connect to AC to the ground, the other AC lead to the motor or pickup
bracket.  Connect the - and + wires together, and connect your light
directly to the two AC leads.  Then find a good place to put the plastic
doo-hickus.

This basic system has limitations- it's quick, and cheap, but it's also
limited.  First, if you want to use it to light cabooses, passenger cars
etc, you need to place something for a "ballast", a current limiter in
series with the diode/bulb setup.  If you just use the diodes, and apply the
full 12-18 volts, the current through the diodes will heat them and they'll
self destruct. Luckily, the most common failure mode of the diodes is to
short, so the bulbs won't also be fried.

The most common ballast is a small light bulb, rated for the full voltage
and with a high enough current rating that it will pass enough current for
the target bulbs to light as well.  In many cases, a common auto dash light
bulb will work.

Of course, now you have a big bulb, generating heat and light you need to
get rid of, but no one said it was all easy.

Finally, if you are using one of the many new, high efficiency motors common
in the hobby, the motor won't let you use this series circuit.  All the
current required to light the bulb has to pass though the motor, and the
motor might not draw enough current, even at stall, to light them.  So for
these, you need the ballast, or some sort of "active" electronic package.

Let's get back to the original topic.  LL engines are a maze of hardware
with wires going every way.  But see if you can find the wires that go to
the truck pickups, and to the motor brushes.

Temporarily disconnect all of them.  Use clip leads or wet noodles,
whatever, to connect one motor brush directly to one truck pickup.  The do
the same for the other motor lead and a truck pickup on the other side of
the engine.

Test it.  If it still runs faster in one direction than the other, it's a
mechanical problem.  Note: For this test to mean anything, you should really
make sure the electronics board is /not/ in the circuit.  One end can still
be connected, but the bulbs should not light, etc.

I've got four LL E8 units to trouble shoot.  None of them run the same
speed, and including the forwards and reverse speeds, nothing runs together.
They're pretty far down on my priority list, though.

Fred Dabney, watching the action from BNSF MP 1112, El Paso sub.

It was me who started this thread and I'd like to thank those who
responded with technical fixes to this problem.

Just to bring you up to date I found the Life-Like web site and sent
them a "Feedback" email describing the issue.  I received a reply that
indicates they do not give technical support via email however they do
have a technical support phone line which is:

1-800-638-1470

So I am going to give them a call -- I'll post a note to this group to
let you know of their response -- in the meantime if any of the rest of
you folks want to call them --- go for it.

Thanks again to those who responded and if anyone else has a simple
wiring fix to this problem please post it so the rest of us can benefit
from you expertise.

Best Regards,

...interesting problem...anybody have any thoughts on all this ?...

...big john...   :))

...big john...   :))