Discussion in 'DCC & Electronics' started by lester perry, Jan 7, 2008.

  1. lester perry

    lester perry Active Member

    I have a problem with locos stopping because of momentery break in power due to dirt or loss of contact or gremilins or whatever. Ihave heard that a capacitor put in line will solve this problem. Does any one know any thing about this?
  2. Jim Krause

    Jim Krause Active Member

    It might work, but shouldn't be necessary for the conditions you describe. The capacitor will give an initial burst of current when it discharges but wouldn't help if the loco didn't clear the bad spot in the track. You would still get jerky operation. My thought is that it would be easier to correct the basic problem.
  3. rogerw

    rogerw Active Member

    I would think you would need a good size capacitor to make a difference.
  4. pgandw

    pgandw Active Member

    There are some decoders designed to accept "keep alive" capacitors. In most cases, the capacitor prevents the decoder from resetting itself when there is a momentary power interruption. The decoder must have a way to tap into the circuits behind the bridge rectifier input.

    I believe the Lenz Gold decoder has an option for a "keep alive" capacitor to help keep the motor turning as well. Capacitors to power both motor and decoder for even a second or two are not small, and must be wired to the decoder correctly.

    Note that a big keep alive capacitor may experience some of the same inrush current problems as QSI and other sound decoders, where the inrush current is big enough to trip the DCC system circuit breaker. And the inrush currents are additive - each inrush current adds to the total load when the DCC system is turned on or reset.

    Before DCC, flywheels were the accepted way of providing stored energy to get past a momentary power interruption. Flywheels also have the benefit of resisting changes in motor speed, causing smoother running, especially during starting, stopping, and at slow speeds. And they add weight to the locomotive, which is good for traction. If the flywheel(s) is big enough, the model locomotive can actually coast a few inches when the power is shut off. Note that a flywheel does nothing to prevent a decoder reset during loss of power. It may help the engine coast past the dirty spot on the track to where it receives power again.
  5. lester perry

    lester perry Active Member

    I am aware of flywheel keeping loco moving, I have some that will move about 6 inches after loss of power I have not put decoders in them yet.
    all of my power have flywheels but most will not coast. and cleaning the track is very temporary sollution. this is a problem I have brought up many times here and it appears that I have triedevery thing I can to eleviate the problem with no success
  6. woodone

    woodone Member

    Yes a capacitor will help. Are you a N scaler or HO ?
    I have installed some sound units into N scale and found that a 200 uF helped very much. If you can install a larger value all the better. In N scale I just ran out of room for anything larger. I had to use (2) 100 uF surface mount capacitors that I wired up in parallel. With HO you can use somthing much larger if you have the room, like 2200 uF.
    One of the sound manufactures furnishes a capacitor with there decoder.
    The decoder has wires to hook up the capacitor, so you get it hooked up right. The larger capacitor will allow for a longer none contact interuption of power.
  7. MasonJar

    MasonJar It's not rocket surgery

    I have seen a Lambert Mack RailBus with the Lenz set-up that is mentioned above. It performed flawlessly over insulated frogs. In fact, it could not cross insulted frogs without it, as the bus only picks up power on the (two) rear wheels. I'll have to look at doing this to mine at some point in the future...

    A Lenz Gold decoder is required to do this, plus their "USP" unit - Uninterruptable Signal Processing (I think that's what they called it).

  8. Dansco

    Dansco Member

    Man I love this forum! I had no idea such a thing existed. I had a neat little engine with only 4 wheels that would stop in most all my snap switches, had I known about this I might not have sold it!

  9. MasonJar

    MasonJar It's not rocket surgery


    Bear in mind that the Lenz "solution" costs upward of $75, more if you want to have someone install it for you...

  10. gcodori

    gcodori Member

    Ask and ye shall receive...

    Seeing a demonstration of the Lenz Uninterruptable Signal Programmer that cost about A$70 that has to be connected to a Lenz Gold decoder about A$70 I was very impessed with how good it works

    How to build your own "stay alive" circuits to many brands of decoders, and how to adapt them to work with yours. You just need to identify the rectifier that takes track power on the decoder. Many decoders are listed on the page to get you started.

    The site also has some nice NCE mods you can do as well.
  11. woodone

    woodone Member

    Hay! what a neat link- some very good information on that site.
    I have it bookmarked so I can use it again.
  12. woodone

    woodone Member

    Yes it will, and you will have to find room ( empty car ) to put it into.
    You might find room in HO, but with N your going to be pulling a car behind the locomotive with the Lenz set up, hooked up inside the car.
  13. 60103

    60103 Pooh Bah

    One of our dealers used to demonstrate the Lenz system by running a loco over a sheet of paper over the rails.
  14. MasonJar

    MasonJar It's not rocket surgery

    The Lambert Mack Railbus was an HO model, and the decoder and USP unit fit in its baggage compartment, allowing a fully detailed passenger compartment.

    The baggage compartment on the bus is les than <1x<1x~1/2", so it may be doable in Nscale steamers with roomy tenders. Diesels - maybe not...!

  15. railwaybob

    railwaybob Member

    Before installing capacitors onto decoders, make sure you have power pickup on all wheels. It's a lot cheaper to install pickups than to fool around with capacitors on decoders.

    Clean tracks are even more essential with DCC as DCC is not as forgiving as DC when it comes to dirty tracks. A "bright boy" or sanding sponge will do the job if used on a regular basis.

    Bob M.
  16. woodone

    woodone Member

    With N scale, by the time you get the decoder and speaker installed there is very room left, you have the strugle to fit the wires into the small space left. Most N scale tenders are no where near 1"x1"X 1/2"inside. :eek:
  17. woodone

    woodone Member

    Sanding sponge? I would stay away from any sand paper in any form. Bright boys, Humm- you might leave scratches in the rail- better place for the dirt to hang on to. Try to polish the rail, and not scratch it. The more scraches the better the dirt will stick to the rail.
  18. lester perry

    lester perry Active Member

    thanks to everyone for the tips. I have been looking at all of them and I think the capacitor idea has merrit. an I am going to try it . the only problem is I need to find someone to install it as I can't solder very well since the stroke but I will find someone to help out. Will let you know results when done. it may take a little time
  19. Harold Cole

    Harold Cole Member

    Les, i would be more than glad to help you out,just let me know.
  20. woodone

    woodone Member

    A helping hand

    Hi Harold,:wave:
    Good to see someone offer a helping hand to Lester.
    I think that is what the hobby is all about- helping each other. :thumb:

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