Adding LED lights to older Bachmann plus dc locomotives Issue

[electrical whiz kid]

For those of you following this thread and aren't all too familiar with what is being discussed. Len meant that the cheapo xformers lack a lot of parts necessary to rectify and smoothly filter down AC to get a good DC current flow.  How this is accomplished is analogous to water flowing in a tube.  If you have variations in pressure and volume, and want constant pressure (DC ), you would install devices to make volume and pressure constant. 
In electricity, volume is equivalent to current (amps), and pressure is EMF (a fancy way to say voltage)...  In electricity, AC would look like a standard sine wave on a chart.  If you take out-say-the bottom half of that wave, you have half-wave voltage-or rectification, if you will.  Now, there are ways to use that negative component.  One would use capacitance, which would act like a pump in our water analogy.  This, combined with some one-way valves (diodes), and some resistance-and if you want to get fancy, inductors (coils) would give you a fairly smooth-acting appliance.  Now, all of this would be done on a high-grade transformer , and it would (supposedly) leave you alone.  As Garfield said; if you want to have class, you gotta spend money...  This was a pretty basic explanation, but using it, I tried to convey some basics just to get you the idea.

Rich C.

[jbrock27]

...check out this page: http://sumidacrossing.org/LayoutElectricity/ModelTrainPower/PowerPackTesting/
Len

Len, I have been reading this.  If refers a lot to "modern DC motors" and the ones that are not as being ones that are impacted.  So, it begs the question, what defines a "modern DC motor"?  Gotta think Bachmann Plus motors fall into the "modern" category.  Agree?

[Len]

jb - Agreed.

I wasn't too concerned with the motor discussion on that page. I was mainly interested in the O-scope pictures showing the transients and overshoots that can do "not good" things to LEDs if not dealt with properly.

Len

[electrical whiz kid]

Len;
I am the first guy to say I know diddly about LEDs, but would an inductor and a cap in that LED/resistor circuit, if used right, tend to smooth out the voltage, and restrict the transients to a minimum?  I find similar problems in dealing with the new lighting systems out there.  As you know, the emphasis today is on using LEDs to replace other forms of lighting; but, there are load considerations, effects like 3rd harmonics, etc to deal with.  In industry, one would approach this differently than a modeler, but it is essentially the same thing; AC being rectified to DC.
Rich C

[Len]

The .5uf cap in the diagram I posted earlier eliminates, or at least cuts to to a reasonable level, the transients that would damage an LED used by modelers.

I don't know enough about the new LED bulbs for household use to comment on them. Except to say my electric bill went way down when I switched to LED bulbs throughout the house.

Len

[electrical whiz kid]

Len;
I didn't catch that post.  OK.   We are thinking along the same lines.  The scope would show a sine wave (AC), and transients as well.  I learned the basics of the scope in Air Force tech school at Chanute; Having done so, I have only had occasion to use one twice-in fifty years...   Boy...am I an expert, eh?
Actually, I have in my collection, a myriad ménage of gauges, meters, et al that would work for me probably for another hundred years...  Actually, this field is constantly morphing at an exponential rate.  The 2014 NEC/NFP70 is bigger and better than ever...
even with those thinner pages...  There is now stuff on generators, PV systems, that was never in there until now.  The hard-cover issue costs around 100 dollars.  I am glad I am "retiring"...ANd I do not envy the "young'ns".

(tired old) Rich C.

[jbrock27]

I was mainly interested in the O-scope pictures showing the transients and overshoots that can do "not good" things to LEDs if not dealt with properly.

Len

This is not addressed in the findings/report, correct? You are drawing this inference from this guy's readings on his O-Scope, correct?

[Len]

I was mainly interested in the O-scope pictures showing the transients and overshoots that can do "not good" things to LEDs if not dealt with properly.

Len

This is not addressed in the findings/report, correct? You are drawing this inference from this guy's readings on his O-Scope, correct?

Yes, as I explained above, I pointed to the page because of the O-scope pictures showing the transients. They are very similar to the O-scope pics I tood several years ago. Pointing to them saved me the hassle of digging mine out, scanning them, and posting them here to show what I meant by 'transients' and 'overshoot' on power pack outputs.

Len

[jbrock27]

Does it provide any explanation then, to why I don't have the problems the OP (JA) is experiencing, since I am using a "modern" motor and have my LEDs (with resistors inline) connected directly to the contacts on the "modern" motor?  Another way of saying it, does the modern motor being used in conjunction with the LEDs reduce the impact of these transients and overshoots?

[Len]

If the LEDs and resisters are wired in parallel with, and directly to, the motor it will reduce the current, and spikes, getting to the LEDs. The inductive load of the motor may do some smoothing, but not as much as a capacitor would. It's still definately better than going directly from one rail pickup, through the resistor to LED1, directly to LED2, then back to the other rail pickup with no capacitor.

Best scenario, wire them in parallel with the motor and use a capacitor.

Len

[jbrock27]

If the LEDs and resisters are wired in parallel with, and directly to, the motor it will reduce the current, and spikes, getting to the LEDs. The inductive load of the motor may do some smoothing...

Len

Thanks Len, this would explain why I am not having problems.

[electrical whiz kid]

Len;
What type of DC  motors is Bachmann using in their product?  I know there is a variation in design per model requirements, but the type should be essentially the same, no?  Using an ammeter and running [them up] under no load, they seem to be nice and smooth, no sudden drops, spikes, etc.

Rich C.

[jbrock27]

Modern, can.

[electrical whiz kid]

Jim;
I guess I didn't make myself clear.  Was this a standard construction-EG:  Commutator, brushes, etc-or was it something on the order of brushless motors.  Brush-less motors are a pretty good proposition.  The less parts, generally the better off you are.  OH, BTW:  Bowser and Precision Scale both have those tender trucks I was looking for. 

Rich C. 

[jbrock27]

Ahhh.  Sorry Rich, can't help there.  If I had to guess and this is just a guess, I would say no, they are not brushless.