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Discussion Starter #1
Has anyone ever installed a large capacitor into a DC track-powered loco along with some circuitry that (a) maintains correct polarity on the cap, and (b) automatically discharges the cap across the main loco power buss (but isolated from the track pickups)  if the track power fails momentarily such as when encountering dirty track, a dead track section, or the problematic frog of some mass-mfrd switches?   A challenge would be to have the circuitry "remember" the track voltage level at the time it dropped and limit the capacitor discharge voltage to that same potential until track power was restored.

The benefit of this over DCC would be no requirement to buy controllers or do any programming to gain smoother performance using traditional track power on electrically less-than-perfect track.
 
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Posted By Al McEvoy on 02/27/2008 7:41 AM


 if the track power fails momentarily such as when encountering dirty track, a dead track section, or the problematic frog of some mass-mfrd switches?  

Hey Al, With a Battery and RC setup all of those above problems would not exist!...just a thought:)
 

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Posted By calenelson on 02/27/2008 7:58 AM
Posted By Al McEvoy on 02/27/2008 7:41 AM


 if the track power fails momentarily such as when encountering dirty track, a dead track section, or the problematic frog of some mass-mfrd switches?  

Hey Al, With a Battery and RC setup all of those above problems would not exist!...just a thought:)


Your point is well-made Cale, but my objective here is dirt cheap improvement.  I'm not advocating any particular power source - that is best left to other discussions.  But for those with very limited funds - and there are plenty of them - this could ease some of the running problems that DCC power mostly resolves and battery power completely bypasses - at a fraction of the cost.
 
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RE: "Hybrid" Power?

Understood, Al...

"for those with very limited funds - and there are plenty of them"


Yessir-I am one of those! With 3.5 kids, and I beleive simple battery power is a "dirt cheap improvement" over traditional track power on "electrically less-than-perfect track" for those on ltd budgets.

example: I have a HLW Mack Switcher with 9.6v inside (RC car battery pack) and a DPDT switch for direction...once charged it runs for about 5/6+ hours up/downgrade with consist. One could simply add Del's "Critter Control" for less than $75 and have speed and direction...for a little more they could do the RCS/EVO control with a 2 stick transmitter.

Please don't think I am discounting your idea or trying to steer the discussion away from your original post, rather trying to shed light on the "Cheap" "fixes" that are already avail!-

Good Luck!

cale
 

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RE: "Hybrid" Power?

Al, I don't know how to do this, wish I knew more about electronics so I could. But I know manufacturers do this. My LGB Mike has this built into it and I believe my Bachmann K-27 does also as it seems to handle dirty track very well.

A fella named Stan Ames was working on a hyrid drive for DCC:
dcc hybrid drive
 

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Al, There are many problems to consider.

First, the capcaitor must be HUGE!. To get 1 second or run time from the capacitor, it would have to be close to the size of your engine.

Next, when you first turn on your track power, the capacitor would appear as a short circuit for a short period of time until it charged.

Last but not least, you would have to maintain correct polarity on the capactor at all times. If you ever get the power reversed, it would short out your power pack and release the insides of the capacitor all over the place.
 

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RE: "Hybrid" Power?

Bill, I have no electronic background at all, and I'm clueless about it, but I know some manufacturers must do something like this. My LGB for example will handle dirty sections of track and keep on going, and it also still plays sounds (maybe 20 seconds or so) after the power is turned off. Is this another technology that is used? Do you know?
 

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David Bodnar does exactly what you are asking and uses two big caps with appropriate electricity routing.  He is a member on this site, but a regular at the "other" site and I believe the "other" site has his plans and schematics of what you are requesting to do in archive.
 

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RE: "Hybrid" Power?

Gentlemen, Bill Swindell is quite correct. You can think what you will, but capacitors have been around for a long time; they ain't rocket science and very little math is needed to understand them.

What is important is the RC Time Constant: Resistor value multiplied by Capacitor value gives Time in seconds. If a resistor (or resistor equivalent) is placed across a charged capacitor, it discharges to 37 percent of original value in one RC time value.

The RC time constant is in seconds if the capacitor is in farads and resistor is in ohms. So a 1 farad capacitor and a 20 ohm resistor has an RC Time Constant of 20 seconds. And of course if the capacitor value is in microfarads and the resistor value is in megohms, the time constant is still in seconds. And 37 percent of 20 volts is 7.4 volts.

A 1000 microfarrad capacitor and a 20 ohm resistor has a time constant of 0.02 seconds. One half cycle of the AC voltage is 0.0083 seconds long.

A 20 ohm resistor across a 20 volt source draws one amp. So you can approximate the equivalent drain of an engine. And a one farad capacitor is huge.

The inductance of a motor will have an effect on the RC Time Constant, but only if it is high and if there was circuit continuity.

The reason music will last a bit longer is because the circuitry's resistance is high.

Art
 

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RE: "Hybrid" Power?

Thanks for the lesson Art, it still seems like rocket science to me :) I've vowed to learn more about electronics because I'd love to do some of this stuff.

Maybe instead of capacitors use a few rechargeable batteries then?
 

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RE: "Hybrid" Power?

Had to learn this stuff back when the Navy got me in 1945, jimtyp; I think it's easier to learn when you're young. Neither batteries or large capacitors come in 'AC', so backing up presents an additional problem. This can be solved by rectifiers but the hazards of exploding capacitors - or batteries - are really not good.

While working for IBM back in the 50's, I had the end covers off a big power supply, larger that a side-by-side freezer/refrigerator, when one in a bunch of capacitors blew. Fortunately, the plastic shield held; I just aged a few months. These 'safety-covers' had just been recently installed as several employees had been injured by exploding caps.

Art
 

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Posted By calenelson on 02/27/2008 7:58 AM
Posted By Al McEvoy on 02/27/2008 7:41 AM


 if the track power fails momentarily such as when encountering dirty track, a dead track section, or the problematic frog of some mass-mfrd switches?  

Hey Al, With a Battery and RC setup all of those above problems would not exist!...just a thought:)




 
Even after we split power up into distinct sections, the battery people keep propagandizing in non-battery sections.

Please, Cale, respect the people who post here and keep your propaganda in your own sphere. We do not want to have the nonproductive power arguments restarted.

Mark


 
 

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RE: "Hybrid" Power?

I think I would have aged more than a few months! Good thing for the covers, and just in time! I assume that would have been as much fun as poring acid on your face?

I don't want to hijack Al's thread so ... any suggestions for Al's hybrid drive?
 

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I actually tried what you want to do with an HO streetcar. I wanted an electronic flywheel. I tried hooking capacitors in the range of 1000 mfd across the motor. I saw no change from the motor without the capacitor.

Batteries are a good idea except the really don't like to be discharged to 0 volts.

As for the sound, I just took the electronics out of an LGB locomotive. They have a bank of 10 farad, low voltage capacitors in there. That is how they keep the sound going for a short time after the track power is turned off. Four of thos capacitors inn series would give you 2.5 farads @ 10 volts. You would probably want 16 of these capacitors in series/parallel to give you 2.5 farads @ 20 volts. With that much capacitance, you would probably see some coasting effect on your engine. I never figured out how to handle the reversed polarity when you want to back up.
 

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Posted By Schlosser on 02/27/2008 2:39 PM
Had to learn this stuff back when the Navy got me in 1945, jimtyp; I think it's easier to learn when you're young. Neither batteries or large capacitors come in 'AC', so backing up presents an additional problem. This can be solved by rectifiers but the hazards of exploding capacitors - or batteries - are really not good.

While working for IBM back in the 50's, I had the end covers off a big power supply, larger that a side-by-side freezer/refrigerator, when one in a bunch of capacitors blew. Fortunately, the plastic shield held; I just aged a few months. These 'safety-covers' had just been recently installed as several employees had been injured by exploding caps.

Art


First mainframe computer I worked on had several 48V 5000 uF electrolytic capacitors in it (6" long, 3" diameter). One of the first test steps was to get on a ladder to physically look at them to verify they were installed correctly (little molded in "+" sign on the "right" bus bar).  

Measuring them with a VOM was iffy at best.  Sometimes you just could not tell which pole was the positive, especially because there were so many in parallel on the power bus bars

One day. Day shift claimed to have verified a new computer chassis and yet one "blew" when they applied power.  The guy was in big trouble for allegedly "not checking".

When I came in for Night shift I was admonished THREE times (my Shift Foreman, the Department Supervisor and THE Corporate Director of Safety) to be sure I checked them.  I DID, under the supervision of the foreman, even!  BUT... Mine sounded like a cherry bomb in a trashcan when it went!  Blew brown/black sticky foil and paper all over the place!  I pulled a dozen caps from stock and found the manufacturer had assembled about 1/2 of them with the end plate 180-deg out, which could not have been easy since the connections inside were not symmetrical.


As to the question here.  A cap could hold power for a sound card or a low current lamp for very minor power interruptions, but not a power hog like a motor.  This would require a high current capacity battery and if you are going that far, get rid of the track power and just run from the battery.  Or go Live Steam and forget electricity all together!
 
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Careful Charles....Mentioning batteries or even live steam here could get you burned!..

Al, I am sorry to have muddied the waters for you and those responding to your post...

Good Luck with your endeavor!

cale
 

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Posted By Bill Swindell on 02/27/2008 3:25 PM
 I never figured out how to handle the reversed polarity when you want to back up.


I told you guys that Dave Bodnar has already figured all of this out and it is included at the "other" site.  He did an article in Feb 2006 Give Your Engine the Capacity to Ignore Dirty Track.  No sense in reinventing the wheel.
 

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Posted By toddalin on 02/27/2008 3:59 PM
Posted By Bill Swindell on 02/27/2008 3:25 PM
 I never figured out how to handle the reversed polarity when you want to back up.

I told you guys that Dave Bodnar has already figured all of this out and it is included at the "other" site.  He did an article in Feb 2006 Give Your Engine the Capacity to Ignore Dirty Track.  No sense in reinventing the wheel.
You mean this one Todd?

Give Your Engines the "Capacity" to Ignore Dirty Track
 

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That would do it Steve.

I would have posted the schematics, but it's Dave's thing and it is on the other site which is pay for view.  I respected both parties by simply alluding to it.  Dave is a regular on this site and I figured that if he wanted it posted, he would post it here. 
 

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Hey, I run Live Steam... I am used to getting "burned"....  Besides, isn't this the "Traditional Power" forum?  Ain't steam the most traditional power for a train?

Yeah, I know, "Shut up, Charlie!"


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