Electrofrog points wiring

Discussion in 'RTR Trackwork' started by Bear, Jan 14, 2017.

  1. Bear

    Bear Full Member

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    Gday folks.With regard to the electrofrog points, I have designed a little circuit that allows the frog to be powered from a relay, without having to cut the little wires.

    It always bugged me that even though the frog gets powered, there is a small section of track (the moving blades of the points) that still relied on the side contact with the rails for power and needed cleaning. The reason you normally have to cut the wires is the timing of the blades moving and the frog polarity switching is nearly impossible to coordinate successfully and will always end up with a dead short. My design cuts the power to the frog, switches the blades, then re applies the frog power with the opposite polarity. This should make shorts impossible and the entire length of the blade will be powered from the frog.What I intend to use is a Gaugemaster GM500 latching relay and 2 DPDT 12V relays. The frog power runs through normally closed contacts of the relays in series.. The power for the switch motor runs through a normally open contact of each relay and is also connected to the coil of each relay. When you switch the points, the relay opens the NC, closes the NO (solenoid for points operates as well as the GM500) .When the pulse from the Ecos is finished, the DPDT relay de-energises, closing the NC frog power contact, with the changed polarity courtesy of the GM500.

    Hope this makes sense, I will draw a schematic up and post, but electrically, I know it will work. I am just waiting on delivery of the GM500s from England. One GM500 relay will be able to do a crossover as they have 2 sets of contacts. The frog polarity is opposite on each turn out.The only limitation I can think of is that you CANNOT operate the points manually. As the latching relay would be in the wrong position, it would be an instant dead short.
     
  2. Ron

    Ron Full Member

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    Looking forward to seeing the diagrams, sounds as though it will be a great idea :)
     
  3. Bear

    Bear Full Member

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    No worries Ron. It is all in my head at the moment. I think I will just draw it on a piece of paper and take a photo :)
    As the guys from work often tell me , "you have created a solution for a problem which didn't exist"

    Just found my first flaw. The relays will need to be 4 pole DT as they need to break the frog power to 2 points, not just one. No big deal as the relays I have are 4PDT anyway ($2 specials from china)
     
  4. Bear

    Bear Full Member

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    This should work. In the past, I have operated 2 point solenoids and a 12V auto relay from one output of a Hornby Acc decoder with 100ms pulse with ease. The stock pulse from my Ecos is 250ms so should work even better. It all depends on if the accessory decoder can supply enough juice for the 4PDT relay, the GM500 and 2 point motor solenoids all at the same time. I think they can. I will find out in a couple of weeks when the GM500s turn up.
    [​IMG][​IMG]
     
  5. Dave C

    Dave C Full Member

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    Hi Bear.
    This seems remarkably complicated, but given I've returned to railway modelling after decades I may be missing something obvious having previously only been exposed to Hornby Dublo track.
    I made a decision to go with Peco electrofrog points for enhanced running powered by PM1 point motors to switch the frog. Following the instructions I cut the 2 joining wires, then soldered a link between the outer rails and the switch blades.
    Am I missing something (and I'm 12v DC operation so perhaps its a DCC thing?).
    Drc
     
  6. Bear

    Bear Full Member

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    Hi Dave. I guess I am just used to looking at schematics all day but it is fairly simple. The 2 4PDT relays are sort of "control" relays that kill the power to the frog, switch it, then power it up again. This is so you don't have to cut the little wires.
    The design can be used for both DC and DCC equally. It keeps polarities separated, whether they be DC or AC.
     
  7. Dave C

    Dave C Full Member

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    Ahh. This presumably allows you to dispense with the point motor and combined accessory switch as well and use a simple solenoid?

    Drc
     
  8. Bear

    Bear Full Member

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    Yes, certainly can, but if you already have the combined units, you can use the contacts of the accessory switch in place of the GM500.
     

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