# Aristo passenger car conversion to DCC



## CliffyJ (Apr 29, 2009)

I have some Aristo passenger cars, each with 6 incandescent bulbs, ~12v type. When I was using DC, I switched the bulbs to 28v, to shine less brightly and make the bulbs last longer.

Specifically, the bulbs are 28v, .04A, made by Eiko: http://1000bulbs.com/product/8322/I...4Aodh24A0w

The lights seem to run fine on DCC, but these 28v bulbs are now seeing ~21v, correct? So they're pretty bright again, and I'd like to knock that down. I should have put out an alert that I'm electronically challenged, but most of you know that already. Anyway, a single diode across either feed to the car gets the brightness down, I'm guessing because it's chopping out half the DCC's power. And is that all I need to do for incandescents? I've got plenty of these 3A diodes, and would rather not use bridge rectifiers, nor do I see a reason to convert to DC. Please correct me if/where I'm wrong!

BTW these Aristo cars are tough to rewire (the circuit board is sandwiched between the floor and the undercarraige), but there seems to be an opportunity to add diodes in each truck, at the pickup. I tried to find a thread on the topic, no joy. Any links to share on this?

Thanks,
===>Cliffy


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## chuck n (Jan 2, 2008)

Cliff, I am more electronically challenged, you have added DCC. Couldn't you use a resister rather than a diode in the circuit? They have the advantage of allowing current to go in both directions as apposed to one way. No bridge rectifier needed. Chuck


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## Greg Elmassian (Jan 3, 2008)

since incandescent bulbs run on voltage, not current like leds, you want to drop the voltage. 

Diodes would work, but you would be getting 1/2 wave DC... try this circuit: (the one on the right... a full wave bridge with one or more diodes in the middle... you can construct this whole thing from individual diodes)

see my page: *http://elmassian.com/tra...trong>**









*


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## chuck n (Jan 2, 2008)

Greg, in his original post Cliff mentioned adding a diode to the wiring on each truck. Couldn't a small resistor be added to one of the wires in each truck, from the same side, and reduce the voltage, without building a diode bridge? I use a 10 ohm resistor a couple of feet in front of the diode I use to,stop my train on a point to point track. Rather than have the train come to a sudden stop it slows down by about half before it stops. It is visually a little less jarring. A resistor in a wire coming from each truck should have the same effect on the bulbs. Chuck


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## Greg Elmassian (Jan 3, 2008)

Yes, but it would not work as well.... diodes have a constant voltage drop irrespective of current. 

Resistors vary and he would have to measure the current of the lights at the desired voltage and then calculate the appropriate resistor, and also double check the wattage. 

Again, incandescents are really "controlled" by voltage, so you want a voltage dropper that works irrespective of load. 

If these were LEDs, then the recommendation would be resistors. 

Also, variations in voltage on the rails would have a greater effect on the lamps using resistors, while diodes will, again provide a constant and consistent voltage drop. 

The output of a lamp is nonlinear, light vs. voltage, so you really want to control voltage, current will not be an indicator of brightness... 

Regards, Greg


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## chuck n (Jan 2, 2008)

But doesn't DCC supply a constant voltage to the track?

Chuck


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## Greg Elmassian (Jan 3, 2008)

The answer to the question is yes... but when I do electronics, I try to make them operate in different environments, different track voltage, etc. 

Only DCC systems that supply a regulated output have really constant voltage. 

But the question is more of how easy it would be to drop the voltage... In this case it's even easier since Cliff has lots of the building blocks, diodes. 

In the circuit I have shown, the lights will work on DC and DCC and just adding or subtracting diodes from the center "chain" makes for easy fine tuning. 

With resistors you will have to calculate and find the right resistor... 

Greg


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## Dan Pierce (Jan 2, 2008)

Even though DCC supplies a constant voltage to the track, my system has a voltage control adjustment and my track voltage can be set from 14 volts (think HO here or even N scale) to over 24 volts (I could use 28 VAC input, but I have 25.2). 

The other method would have been a bridge rectifier and a LM338 regulator set to 20 volts for the 28 volt bulbs. 

Myself, I would have rewired the 12 volt bulbs in series for 2 at 24 volts and use a regulator to lower the voltage or use leds in series and then just use 1 resistor. Both of these methods need the bridge rectifier, and a capacitor would help the leds on intermittent track power contact.


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## CliffyJ (Apr 29, 2009)

Thanks Chuck and Greg, you've given me more to think about.

Greg, for the record, this was one of those times I DID go to your site before posting here. So thanks for that link... I missed it!

Not that you guys need it, but here's the area of my interest:










The black deck won't pull off, because it, the trucks, the body (with floor, walls, lights) and circuit board all all hard-wired together, with no service loops. 

These pickups are on each truck, and the (hidden) board is already doing the distribution. That's why it would be nice to do something simple, small and cheap to both trucks; and I have 6 cars. 

Greg, I've yet to get a really-bulk pack of diodes, but I do have at least 12 rectifier-type @3A, and about 90 non-rectifier-type @1A. Would the latter work for a home made rectifier? (I should just so see...)

Anyway, if this is going to work on DC and DCC, I see why the bridge rectifier. On DC, a single diode would cut the lights, depending on direction of train; and a resistor would not have the desired effect, with variable DC. 

So, two ways to go: 

If I never run on DC, or sell these cars to anyone, what's the simplest mod here? 1 diode, half-wave DC? Is there a down-side in reliability, heat buildup, or...?

Or, if DC/DCC op is best (and I get it), can I get away with a 4-diode rectifier? Do I have to have the 4 across the middle... oh, wait, that's how you're tuning the voltage drop. Huh... 

Well, to get the same effect as chopping the wave in half, I suppose I'd need to drop from 21v to 12v, which (at .7v / diode) means ~13 diodes, plus 2 more for the bridge... x 2 trucks, x 6 cars... 180 diodes... mebbe that's not the best approach either.

To recap the problem: voltage reduction to all those bulbs, to reduce draw, increase life, and get brightness down to something believable. With DC (0-18vdc), swapping out my 14v bulbs for 28v did that. Now, at 21v, should regulated to DC, and somehow whack the volts down. Or chop the wave in half, and go DCC-only. 

Huh... sorry, my mind just boggled, need to re-set...

But thanks for helping me think this through guys!

===>Cliffy


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## CliffyJ (Apr 29, 2009)

There's a lighting switch on the underside, it would be nice if it were for DC vs. DCC op... Well, it's just on/off. A DPDT could be used to go either straight from rails (DC), or with a diode between (DCC). Big hassle to install that though. 

Back to Chuck's resistor idea for a moment, I was just messing with the calcs:

Bulbs 6 6 6 Amps (ea) 0.04 0.04 0.04 Amps (total) (I) 0.24 0.24 0.24 Input volts 21 21 12 Bulb max volts 28 28 28 Desired op volts 40% 42% 9% Desired op volts 11.2 11.64 2.64 Voltage drop (V) 9.8 9.36 9.36 Ohms (R = V / I) 41 39 39 Watts (W = V * A) 2.7 2.2 0.6 

The power would be coming coming through 2 trucks, i.e., 2 resistors; so maybe a 39 ohm / 2 watt resistor at each truck might work? 

So when put on DC track, say, at 12VDC (column 3), the bulbs would be a lot dimmer (9% of bulb max). But, they'd come on. Of course, they'd vary w/ track voltage, but they already do that. 

Still, I have those 3A diodes... 

===>Cliffy


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## Greg Elmassian (Jan 3, 2008)

you want a bunch of 1 amp diodes, 1n4001 or above. 

radio shack has a 25 pack of assorted ones, $3.50, that's 14 cents each.... clearly less than 2 watt resistors. 

so you can afford the circuit that works all the time in all environments.. I would not mess with half wave vs. full wave... 

Also you need to test the bulbs and see what voltage gives you the desired brightness... 40% voltage will not give 40% light. 

Greg


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## CliffyJ (Apr 29, 2009)

Posted By Dan Pierce on 01 Sep 2013 05:29 AM 
Even though DCC supplies a constant voltage to the track, my system has a voltage control adjustment and my track voltage can be set from 14 volts (think HO here or even N scale) to over 24 volts (I could use 28 VAC input, but I have 25.2). 

The other method would have been a bridge rectifier and a LM338 regulator set to 20 volts for the 28 volt bulbs. 

Myself, I would have rewired the 12 volt bulbs in series for 2 at 24 volts and use a regulator to lower the voltage or use leds in series and then just use 1 resistor. Both of these methods need the bridge rectifier, and a capacitor would help the leds on intermittent track power contact. 
Thanks for your ideas Dan. 

My original move from 14v bulbs (I'd said earlier 12v, I think they were 14 now) to 28v didn't require rewire, and the bulbs were cheap. But point taken, I should just do it right at some point.


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## CliffyJ (Apr 29, 2009)

Posted By Greg Elmassian on 01 Sep 2013 08:55 AM 
you want a bunch of 1 amp diodes, 1n4001 or above. 

radio shack has a 25 pack of assorted ones, $3.50, that's 14 cents each.... clearly less than 2 watt resistors. 

so you can afford the circuit that works all the time in all environments.. I would not mess with half wave vs. full wave... 

Also you need to test the bulbs and see what voltage gives you the desired brightness... 40% voltage will not give 40% light. 

Greg Those 80 or 90 1A diodes I have are 1N4007 I believe. What's the significance of the last digit?

Right on about the 40% thing, as I discovered a couple hours ago. Here's a very rough comparison, the only quick one I could think of. 

Setup 1: 28v bulbs on the 21v DCC rails, no diodes or anything: 75%.
Setup 2: stock 14v bulbs on full DC power (for my MRC throttle, 18v): 125%.

#1 was a LOT dimmer, maybe 1/4 the brightness of #2 if that.

So maybe I'm not too far off, like dropping the 21v to ~18. 

Anyway, this is sounding like I need to dig into the buried board, and modify it:
- preserve 2-truck pickup
- rectify downstream of the dual pickup combining
- add dropping diodes a/r 
- add capacitance for flicker reduction (more research needed...)
- add JST jacks to get the undercarriage off in the future 
- maybe re-introduce smoke stack capability (I've just got them switched off for now), for that once-in-a-while photo op...

At the moment, I think I'm safe in running the cars on the layout without mod's. Which I just did for the first time, a half hour ago, woo hoo! But what what I've seen so far, the above mod's seem reasonable. I'm sure someone's done it already though... 


Thanks again Greg,
===>Cliffy


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## Dan Pierce (Jan 2, 2008)

The last digit of the 400x and 540z is a voltage rating 
1=50v 
2=100v 
3=200v 
7=1000v. 

his is the reverse v rating. 
If you use a diode to charge a capacitor on A/C, you need to figure out the total voltage taht could be across a diode feed ing the cap. 
Lets take a 24 volt transformer as an example. 
To start, many transformers are 25.2 volts, not 24 volts A/C. 
Peak waveform is 25.2 times the square root of 2 (1.414) which is ......35.6328. 
This means in theory a capacitor can be charged to 35.6 volts (of course there is a small voltage drop across the diode. 
Now look at the opposite cycle where the input AA/C goes to negative 36.628 volts and you now have 72.2 volts across the diode and if it is a 1N4001, you have greately exceeded its 50 volt rating!!!!!! 

So, in large scale 100 volt rated diodes are a must and I prefer a much higher rating as the power line can have spikes and these power spikes could make the transformer output exceed even the 100 volt rated diodes. 

Your 1N4007 is a great choice with 1000 piv rating (Peak Inverse Voltage which is what my rant is addressing).


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## CliffyJ (Apr 29, 2009)

That's very informative Dan, thanks very much!


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## CliffyJ (Apr 29, 2009)

I ran the train some last night, my first night run. 

I still think the bulbs might be too bright, but maybe I was too hasty. The problem is that the yellow plastic castings of the car bodies light up like a lampshade. The 28v bulbs definitely help, but it still looks weird.

So I need to paint the interiors. After that, maybe 21v DCC is OK. But for bulb life, maybe bringing it down 2 or 3 volts is still a good idea.

The main issue learned from last night is the flickering; it's far worse than I'd imagined. So if I fix anything, it needs to include that. Here's a stinky video:





There's many continuity and cleanliness issues (wheels and track), so I'll focus on those. But if anyone can think of the simplest constant voltage circuit, without changing to LED, I'm all ears.

BTW, there is an LED replacement bulb for the tiny E5 bulb sockets, but they cost about $11 each -- gulp!

Thanks, 
===>Cliffy


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## chuck n (Jan 2, 2008)

Flickering is a fact of life with track powered car lights. I think that some have build a capacitor circuit that stops the flicker. The other option which a number of people have done is to go to battery with bulbs or LEDs.


Chuck


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## Greg Elmassian (Jan 3, 2008)

Please keep in mind when Dan mentions AC, he really means sinusoidal AC like you find in your house. 

DCC is AC also, but a square wave, not a sinusoidal one, so the calculations he shows (multiplying by the square root of 2) have NO application to DCC... 

24 volts DCC is 24 volts DC when rectified by a full wave bridge. 

1000 volts is way overkill for a 24 volt situation, won't hurt but way overkill. 

Greg


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## CliffyJ (Apr 29, 2009)

Greg, I'm reading your write-up under "Add a capacitor for uninterrupted power" 
http://elmassian.com/trains/dcc-battery-rc-electronics/misc-electronics 

Are there only the rectifier, cap, and resistor involved? If so, it sounds like four 1N4007's would work (got plenty), a couple more for V-drop. Or maybe the resistor is instead, and maybe I have those. That leaves the cap. 

Because of size constraints, can I use 2 or more caps of lesser value, and are their mfd's additive? 

True, the flickering isn't nearly as bad, now that I've cleaned all the rails this morning. So I might not take on this modification right now. But still, it's nice to become familiarized with the factors for later on. 

Thanks, 
===>Cliffy


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## Greg Elmassian (Jan 3, 2008)

That's kind of an old part of my site. 

Actually I would use a negative coefficient thermistor, which basically would be low resistance to run the leds, and high resistance when charging from cold, or I would use the time honored method of a diode to feed the leds and a resistor for the inrush. 

The thermistor is probably the simplest and most elegant solution... 

If you look at the capacitor bank that Aristo sells, there's a thermistor on it. 

Greg


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## CliffyJ (Apr 29, 2009)

Would that work with my incandescents?


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## Greg Elmassian (Jan 3, 2008)

Sure but what are you trying to accomplish, constant voltage, reduction of flickering, elimination of flickering... 

There's all kinds of stuff you can do, but I thought the priorities were cost then simplicity 

If the priority s no flickering, then you will have a more costly circuit 

The question is sort of turning into "what is the best car made"with no priority on cost, handling, passenger carrying, etc. 

Let's tie the requirements down rather than go through every possible solution 

Greg


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## CliffyJ (Apr 29, 2009)

Posted By Greg Elmassian on 02 Sep 2013 06:25 PM 
Sure but what are you trying to accomplish, constant voltage, reduction of flickering, elimination of flickering... 

There's all kinds of stuff you can do, but I thought the priorities were cost then simplicity 

If the priority s no flickering, then you will have a more costly circuit 

The question is sort of turning into "what is the best car made"with no priority on cost, handling, passenger carrying, etc. 

Let's tie the requirements down rather than go through every possible solution 

Greg 
I was close to understanding your capacitor circuit, but you mentioned thermistors, in conjunction with LED's, for this incandescent application. 

Mainly I would like a smoothing out of abrupt on/off voltage to the bulbs. Some variation is fine, because these lamps represent kerosene lamps. 

Thanks Greg,

Cliff


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## Dan Pierce (Jan 2, 2008)

To reduce flicker on one of my passenger car consists, I wired all my cars together and all the cars have track power pickups. 
I even added the engine to all this. Of course I now have wires that show, but no batteries to charge/replace.


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## Greg Elmassian (Jan 3, 2008)

If I was to go to a lot of effort to reduce flicker, which I am going to, and cost no object... then I will put regulated power supplies in each car like 12v and enough storage capacitors to handle the brief interruptions of power. 

One thing that people often forget when trying to eliminate flicker, if you are running right from rectified track power, then when there is an interruption, you MUST have some voltage loss. If you have a power supply that is regulated "down" from the track power, then you can avoid this... but again, it's more expensive and complex. 

So this is what I may wind up doing: 

DCC track power >> rectified and filtered (BIG capacitor) >> DC to DC converter (any voltage to 12v dc) >> a little noise filtering (just old school) >> 12 led strips 

IF you look around, you can find these DC to DC converters cheap, they don't need a lot of current capability. The big capacitor will take space. 

But if you do something like this, and you have like 20-24 volts on the rails, you can clearly get flicker free lighting.. I don't want the wires between cars, mostly appearance, though Dan's method is very inexpensive and works great. 

Greg


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## CliffyJ (Apr 29, 2009)

From what you guys are saying, this is probably way off target, but here goes.









Since I have only 6 cars, I don't mind spending a few bucks on each. But for simplicity's sake, I'd like to keep the "existing" features unchanged, as indicated above. 

The multiple cap's are only to save space. But if that doesn't work, so be it, the cap will have to go up in the car interior. Maybe in the bathroom. 

As I've said elsewhere, the anti-flicker was been helped a lot by just cleaning the rails. So the cap only needs to give some smoothing. 

These lights emulate ~1890's kerosene (or oil?), not electric, so some flicker is fine. Actually, it would be cool to have independent flicker in all 6 bulbs, but I'm not going there at this point.









Questions:

1. Given this info, what's a reasonable way to bring the voltage down to ~14v? Resistor, a few more dropping diodes, thermistor, DC-DC converter, voltage regulator...? I have a few of the latter, and they're cheap enough.
2. With the bulbs at ~14v, they're only drawing .02A, correct? So, .12A per car?
3. With the bulbs at ~14v, and feeding them for, say, 250ms, what would be a good mfd value for a single-solution cap?
4. And can you split the caps as shown above, and expect their values and effect to add up?

===>Cliffy


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## Greg Elmassian (Jan 3, 2008)

dropping diodes as per the circuit I gave... the "voltage dropper" made from a full wave bridge. 

If you were using LEDs, you would need a full wave bridge AND a properly calculated current limiting resistor 

Since you are using incandescents, you need just the voltage dropper... it passes AC... but it only goes on one "leg" of the power from the trucks, so run the blue wire ONLY to the switches. 

run the green wire ONLY to the voltage dropper and then on to the lights, caps, etc. 

Greg


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## CliffyJ (Apr 29, 2009)

Closer?










I don't think I interpreted correctly, but I couldn't see how else to wire in the rectifier...?


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## Greg Elmassian (Jan 3, 2008)

"run the blue wire ONLY to the switches" 

so blue goes to to purple 

purple only to switches 

purple not to dropper 

go back the circuit I provided above... the dropper is the right hand circuit. Notice it has ONLY 2 connections to the world? Green wire to one.. yellow to other.. 

You don't need the full wave bridge function to rectify the track voltage, the smoker and the lights are analog... polarity insensitive.. 

Greg


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## CliffyJ (Apr 29, 2009)

OK, the dropper is an in-line thing, on only one of the DCC legs. 
So I read that part of your article again, now I understand better. 
Still, I expected that you had to fully rectify it, so the caps wouldn't melt down. But I don't know nuthin about capacitors.
I'll use your right hand circuit, and give it one more whirl.


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## CliffyJ (Apr 29, 2009)

Speaking of bridge rectifiers, here's some $1 ones: 
http://www.amazon.com/AmplifiedPart...46&sr=8-7&keywords=full+wave+bridge+rectifier 
(edit) 
Well, these are $.55, free shipping w/ Prime. Not sure if it's full or half wave though. 
http://www.amazon.com/Sunkee-Bridge...+rectifier 
(another edit)
Yes, the above are full wave, I was just notified. Ordering some now...


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## Greg Elmassian (Jan 3, 2008)

whups... forgot the capacitors.... dang! looks like there needs to be a full wave bridge too... can't believe I screwed this up... you can put them across the plus and minus terminals on the bridge, then you can save adding another full wave bridge... 

only the caps need to be moved to the plus and minus... 

might be hard to draw... but it's the least components and cost and size... 

sorry, 

Greg


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## CliffyJ (Apr 29, 2009)

No sweat, and good catch.

How's this:










Thanks Greg,

Cliff


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## Greg Elmassian (Jan 3, 2008)

Yeah, I did screw up... the caps don't filter the entire voltage, just part of it.... cute, but wrong. 

Sigh... we will have to add a full wave bridge to convert track power to DC. 

Then, just a single string of diodes to drop to the lights and caps... you can put the caps on "either side" of the "dropping" diodes. 

I am sorry to mess this up for you Cliff... 

Well, at least you are having fun making pretty pictures (yeah yeah don't hit me!) 

Greg


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## CliffyJ (Apr 29, 2009)

No problem at all Greg, I'm the one benefiting here, so thanks! 

Is the schematic of 04 Sep 2013 03:33 PM the best one to date, but (if I read you correctly) with the 4 center diodes located on one of the outputs?


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## Greg Elmassian (Jan 3, 2008)

Use this one and put the voltage dropper in where the resistor is. You could also move it to be between the caps and the lights, have to consider which is best, maybe make no difference. Posted By CliffyJ on 04 Sep 2013 02:22 PM 









Regards, Greg


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## CliffyJ (Apr 29, 2009)

OK, can do. 

Did I mention I have 40 of these coming? They should work for both the dropper and the full wave bridge, right? 
http://www.amazon.com/gp/product/B00D3IWL8K/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1 

Wait a mo', only a string of diodes are needed after the full rectifying, right? Because the dropper would otherwise only be seeing one polarity.


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## CliffyJ (Apr 29, 2009)

I'll put in the "full dropper" if you say so, but here it is with only a diode string:










Betcher gettin sick of this diagram...


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## Greg Elmassian (Jan 3, 2008)

That is exactly what I meant, the "dropper" works with any polarity and/or AC 

Since you are past the bridge, it just takes a single string of diodes since the polarity never varies. 

Greg


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## Dan Pierce (Jan 2, 2008)

I would add a diode to keep the caps away from the smoke unit as the heater element would not care about intermittent power and the element does take a lot of current thus making you need a very large amount of capacitor storage. I see elements up to an amp in some engines, and there are probably units that draw more than that.


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## CliffyJ (Apr 29, 2009)

Posted By Dan Pierce on 06 Sep 2013 05:23 AM 
I would add a diode to keep the caps away from the smoke unit as the heater element would not care about intermittent power and the element does take a lot of current thus making you need a very large amount of capacitor storage. I see elements up to an amp in some engines, and there are probably units that draw more than that. Where would you put it, Dan?


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## CliffyJ (Apr 29, 2009)

Posted By Greg Elmassian on 05 Sep 2013 09:36 PM 
That is exactly what I meant, the "dropper" works with any polarity and/or AC 

Since you are past the bridge, it just takes a single string of diodes since the polarity never varies. 

Greg Cool! 

So I think all I need are the caps. 

1. Voltage. Been some discussion earlier, but these cap's are downstream of ~21v rectifier output, which will be further reduced to ~18 to 14, not sure. How about 25v? Or is that cutting too close?

2. Mfd. Couldn't find a calculation I could understand; so I read your article again, you mention 3k to 50k. Say, for a 1 second power loss, ~18v, .25A in bulbs, how many 1000uf caps would I need in the "mini bank"?

If those val's are ok, how's this: http://www.amazon.com/Gino-Radial-A...1000uF+50V

Cliff


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## Greg Elmassian (Jan 3, 2008)

A diode on the yellow between the caps and the yellow wire from the smoke unit. 

The smoke unit will draw about 1/2 amp, your lights about 1/4 amp... adding the diode will make it so the caps are dedicated to the lights. 

Greg


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## CliffyJ (Apr 29, 2009)

Cool. Thanks Dan and Greg for pointing that out. 

Any thoughts about cap voltage & value & qty (see 06 Sep 2013 02:19 PM)? 

Referring to what you mentioned Greg on Sep 2:

24 volts DCC is 24 volts DC when rectified by a full wave bridge. 1000 volts is way overkill for a 24 volt situation, won't hurt but way overkill. 

After the dropping diodes, the cap's should be seeing about 18v or less. I just want to be sure that there's no other margin to consider, before I order the 25v caps. 

Here's some bargains I've seen so far:
1,000uf @ 25v, $.16, http://www.amazon.com/Gino-Radial-A...amp;sr=8-2
2,200uf @ 25v, $.31, http://www.amazon.com/Gino-12x25mm-...y_e_text_y
1,000uf @ 35v, $.36, http://www.amazon.com/Amico-Aluminu...amp;sr=1-1

As long as I don't screw up on the voltage, and *IF* the 1000uf is in the ballpark, I suppose I can experiment w/ the quantity.

Thanks again guys,
Cliff


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## Greg Elmassian (Jan 3, 2008)

There can be transients on DCC. 25 volts should be enough, but if you can get 35v ones at near the same size, I would do it. 

Electrolytic caps areo notorious for not liking over voltage. 

Just like 50 volt diodes were recommended... 

In terms of capacity, the more the better... but the only way to tell what works is experimentation. 

Greg


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## CliffyJ (Apr 29, 2009)

Roger that, Greg. I just put a couple bags of the 35v on order, should be enough to keep me out of trouble for a while. 
I'll be in a hotel all next week, meaning up later than normal; so maybe we'll say hi in the chat room at some point. 
Thanks again, 
Cliff

PS, here's where things stand. I put in two diodes to separate the smoke unit. Otherwise, just tweaks / notes to the diagram.


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## Greg Elmassian (Jan 3, 2008)

Good. You only need one diode and remember that it also counts in the voltage reduction to the lights


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## CliffyJ (Apr 29, 2009)

Excellent, thanks Greg.


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## Dan Pierce (Jan 2, 2008)

For large scale I go with 35 volt ratings when dealing with track power.


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## CliffyJ (Apr 29, 2009)

Posted By Dan Pierce on 08 Sep 2013 04:25 AM 
For large scale I go with 35 volt ratings when dealing with track power. Sounds like we're all in agreement. Thanks Dan.


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## CliffyJ (Apr 29, 2009)

Decided to tear into this today, in between some deck power washing thrills.

After separating the chassis from the body (which has the circuit board beneath it), and cutting the truck wires to do so, I installed JST jacks for each truck and enlarged the chassis holes to let them through. 










Here's that board. I wanted to reuse as much of the circuitry as possible. Note the 4-diode bridge rectifier, which is there to feed two led signal lamps at the rear of this observation car. Since the other models don't have those diodes, I'm proceeding with putting in my own rectifier for the main lighting, to make them all the same. 











The next mod was to cut the trace in the board (just to the right of the black clip), to insert new diode 1 there. Also in this pic are the breadboard, rectifier and dropping diode chain. 











Testing went surprisingly (for me) well. Messing with different quantities of diodes, it seemed like only two (in addition to D1) were needed for a reasonably realistic feel. 










Here's everything soldered up on the supply end, with everything (including the smoke unit) testing out nicely.

I updated the schematic, based on actually seeing the board, and findings here.











So now, here's where things went to crap.

After carefully checking the polarity, and setting up another breadboard, I hooked up one cap (in parallel with the lights, as shown).

Within 2 seconds, a burst of smoke came out of something, couldn't tell exactly what, but I think it was D1.

I yanked that cap out, and boy, that baby was sizzling, and its ends were bulging out!

"Welcome to Cliffy's Smoke Shop. In this episode, we're smoking only a rectifier and a diode or two, but not a DCC or PSX board this time."









Anyway, diagnosing things, it turns out that the rectifier is toast. And people wonder why I try to get components in bulk on Ebay!









Joking aside, does this cap problem sound like an insufficient voltage rating? Because maybe I should have left in more dropping diodes.

Or, maybe there's a sneak circuit with the existing marker light rectifier...

Or, maybe, despite all my efforts, I succeeded in messing up the polarity (and yes, I did note that these caps are indicated with negative, not positive)... 

Or...?

===>Cliffy


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## BigRedOne (Dec 13, 2012)

Cliffy, 

How about wiring each pair of lights in series? This way you get half voltage to all lights.


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## Greg Elmassian (Jan 3, 2008)

You put the cap in backwards....


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## CliffyJ (Apr 29, 2009)

Posted By BigRedOne on 22 Sep 2013 03:56 PM 
Cliffy, 

How about wiring each pair of lights in series? This way you get half voltage to all lights. Good idea, Red. 

Kinda too late for me now, 'cause my bulbs have all been swapped (I did that over a year ago, before I started into this DCC "conversion"). So I'd be giving about 9v to 28v bulbs, too dim.

But seeing how the board is set up (now that I've torn it all open), I can see leaving the bulbs as-is (14v), and doing what you say. 

Thanks,

Cliff


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## CliffyJ (Apr 29, 2009)

Posted By Greg Elmassian on 22 Sep 2013 07:36 PM 
You put the cap in backwards....


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## Greg Elmassian (Jan 3, 2008)

I thought these were 28 volt lamps, per your first post.... did I miss something along the way? 

Greg


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## CliffyJ (Apr 29, 2009)

You're right Greg, 28v. Did I mis-state something?


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## Greg Elmassian (Jan 3, 2008)

No, just trying to figure out BigRedOnes comment: 

"How about wiring each pair of lights in series? This way you get half voltage to all lights." 

Putting two 28 volt lights in series and running from 20 volts would be REALLY dim, 10 volts to a 28 volt bulb. 


And your comment: "I can see leaving the bulbs as-is (14v)" 


Greg


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## CliffyJ (Apr 29, 2009)

Posted By Greg Elmassian on 24 Sep 2013 09:11 PM 
No, just trying to figure out BigRedOnes comment: 

"How about wiring each pair of lights in series? This way you get half voltage to all lights." 

Putting two 28 volt lights in series and running from 20 volts would be REALLY dim, 10 volts to a 28 volt bulb. 


And your comment: "I can see leaving the bulbs as-is (14v)" 


Greg Right, I wasn't clear. 

For my case, the "two 28 volt lights in series" would be, after the dropping diodes, running from 18 volts, 9v to each 28v bulb. We're in agreement, way too dim.

What I meant was that BigRedOne's idea might be just fine if one were to leave the stock bulbs as-is (which are 14v), and run them on 10v (or less, with dropping diodes). If I'd not already replaced the bulbs, and now that I see the board (you have to cut the pickup wires to do so), I'd probably have tried what Red said. Water under the bridge for me though. 

Thanks Greg,

Cliff


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## Greg Elmassian (Jan 3, 2008)

Ahh... got it, forgot the stock bulbs... 

Yeah, you are WAY beyond that bridge now, ha ha! 

Greg


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## CliffyJ (Apr 29, 2009)

Just a small update. Got back into this mini project today, and all went well with the capacitors. Didn't smoke anything, woo hoo! 

I used 1,000uf caps, and kept adding them... I guess I expected them to hold more charge. With 10, it sure evens things out, but won't power the 6 bulbs for even a half-second. 

Anyway, I put in an order for some cheap 3,300uf caps, and will probably use 4 or 5 per car, and call it a day.


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## Greg Elmassian (Jan 3, 2008)

Yeah, a lot more current than leds. 

I'd try about 10k mfd. 

Greg


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