N scale "What's on your workbench?"

Mark Watson Oct 28, 2009

  1. Inkaneer

    Inkaneer TrainBoard Member

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    Three projects on my short term TTD list. First, adding number boards to two Atlas SD35's. These were unnumbered units I bought along with two numbered units. Second is adding decoders to two Model Power FP&'s. This will be my first hard wire installation. Fortunately Mosel Power left a space for a generic decoder in the rear of the units. Third is to install decoders in two LifeLike C Liners. Awaiting replacement decoders from Digitrax. I fried two decoders on my first attempt at installing them. I wrote up what I did wrong in the DCC and Electronics forum here on Trainboard.
     
  2. TrinityJay

    TrinityJay TrainBoard Member

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    Sad news for me too. As of last night my Arduino servo + relay turnout system (that I thought was mostly finished...) is back on the work bench after I discovered a fundamental flaw. For context, a recent video of the system and a brief rundown in text form-

    Now, it would be near impossible to perfectly synchronize the switchover of both the frog relay AND the servo, which means there will always be a brief short (eg- frog relay switches from +ve to -ve but the point is still in the position that needs +ve until servo moves), and the point of the Block Master relay was to cut the frog bus during this time so that the short didn't matter (circuit not powered).

    What I somehow neglected to consider is that the point blade is still routing power 'backwards' from where it contacts the rails, so the frog relays are still live even with the Block Master disconnecting the frog bus. With the current setup of 2 interlocked points this is probably not an issue, but as soon as I add more to the Block Master relay I am going to briefly short out the mainline on every single throw due to all the +ve and -ve feeds to the frog relays being connected at the Block Master relay. The way I see it, there are 2 possible solutions-

    1. Each point gets its own Block Master. This would completely remove the chance of a short as the frog relays would all be electrically independent. It also means that I would need 3 relays and 2 input pins for every single point, which is what the Block Master relay system was trying to cut down on in the first place. Not ideal, very wasteful.

    2. Purposely insulate the electrical contact between point blades and the rails by painting or adding a clearcoat. This would mean that there's no actual connectivity between the frog and the rails, so it would be impossible to cause a short. As such there would be no need for a Block Master relay, so only 1 relay and 1 pin would be required per point. The downside is the very final tip of the point blade may become an issue due to the small moving joints, should they stop transferring electricity. Also, the point would start shorting on every throw if the paint managed to wear off.

    Thoughts? I'm thinking option 2 is the best bet, as the required resources (and code) are far simpler. Also, it's likely that in time the point blades will lose electrical contact with the rails on their own anyway, rendering the Block Master concept redundant. Note that any solution has to use the relays (I've already bought a lot of them :whistle:) and I'm trying to stay clear of commercial solutions ie- T.V. frog juicers.
     
    tonkphilip likes this.
  3. tonkphilip

    tonkphilip TrainBoard Member

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    TrinityJay - I think that you may be over complicating your issue. If these are Peco turnouts, then you probably have the most reliable turnout in the hobby provided that you do not modify it. I have been using Peco55 Electrofrog for probably 30 years without reliability issues. The switch point blades are very reliable as they flex and mold themselves to the stockrails to ensure good contact on each movement. The secret is to keep paint and ballast off the electrical contact areas. Can you keep your electronics to just switching the turnout positions but ignore the frogs. If you need help wiring the turnouts and inserting insulated joiners, I can help with that. - Tonkphilip
     
  4. tonkphilip

    tonkphilip TrainBoard Member

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    Are you using the new Peco55 Medium turnouts with UniFrog or the traditional Peco Code55 turnouts?
     
  5. Kurt Moose

    Kurt Moose TrainBoard Member

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    That's too bad, I was really liking your build on this. :(
     
  6. CedarCreek

    CedarCreek TrainBoard Member

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    YHrRuVzgTMSi9BusxoXWSQ.jpg I3A1llo+TGCTsmI+HmXKWQ.jpg
    These days the layout is the workbench! Greening up nicely.
     
  7. TrinityJay

    TrinityJay TrainBoard Member

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    Yes, you are right. When you mentioned unifrogs I remembered I didn't make the standard modifications to the electrofrogs I am using because they are borrowed, serves me right for having 'revelations' several hours after bedtime :sleep: Done properly the Block Master relays are completely unnecessary. Thanks for steering me back on course there!

    I understand your view on frog power given your experiences, however mine have been the opposite! We have had endless issues at my club due to people trying to help with scenery and not realising they are ruining the continuity of unpowered frogs. I intend for my own layout to be heavily scenicked and it would only take one slip-up to repeat these mistakes, so I would rather just power the frogs from the outset.

    As for the unifrogs, I would like to use them but space requirements dictate I mostly need the short radius. I would've hoped they were available by now but with the way things are I think it could be some time off yet. I may just end up using electrofrogs if there's no word by the time I'm ready to lay track.
     
    tonkphilip likes this.
  8. jhn_plsn

    jhn_plsn TrainBoard Supporter

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    I sure like this thread. Imagine a thread with a title "What's on your N scale to do list?" Yikes.
     

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