G Ray Stilwell BCD Circuit 5.0

Ray Stilwell's Instant Charge Bipolar Switch Machine control circuit

  1. RBrodzinsky

    RBrodzinsky November 18, 2022 Staff Member TrainBoard Supporter In Memoriam

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    RBrodzinsky submitted a new resource:

    G Ray Stilwell BCD Circuit - Ray Stilwell's Instant Charge Bipolar Switch Machine control circuit

    Read more about this resource...
     
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  2. Pig Gap

    Pig Gap TrainBoard Member

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    This also works for Rokuhan switches in Z scale.
     
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  3. Jonas Grumby

    Jonas Grumby New Member

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    Did he use a maintained switch so that the capacitor will provide a momentary pulse to the turnout and the maintained switch keeps the LED lit?

    On page 1 he said "Although the position of the SPDT switch handle indicates the position of the turnout, a more visible LED indicator circuit is shown in Fig. 2." So it seems like it must be a maintained switch.

    I'm planning on doing this but I bought momentary (On)-Off-(On) switches. I think I should have bought maintained On-On switches. I don't see any reason for an Off position if it's a maintained switch because that would turn the LEDs off and defeat the purpose of using a maintained switch.

    I'm currently waiting for the capacitors to arrive and then I will be ready to test it.

    TIA for any advice.
     
    Last edited: May 1, 2020
  4. Jonas Grumby

    Jonas Grumby New Member

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    I have all of this working now. The maintained On-On switches are perfect. However when he mentions having a "Bicolored LED Indicator" with a SPDT switch in Fig 2 I think he meant that circuit to work with two LEDs of different colors rather than the 3-pin bi-color LEDs that are available now. I'm using one side of the DPDT switch to control the turnout and the other side to control the bi-color LEDs. Works great.
     
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  5. RBrodzinsky

    RBrodzinsky November 18, 2022 Staff Member TrainBoard Supporter In Memoriam

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    It is a two pin bi-color LED. By reversing the polarity, the opposite color illuminates
     
  6. SpacemanSpiff

    SpacemanSpiff New Member

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    Thank you for posting this. The circuit design is simple and elegant

    I wonder if anyone has tried using the circuit in a layout with lots of turnouts. Every time the circuit powers up it momentarily draws about 500 mA, just as if it was throwing the turnout. My concern is that if one now replicates the circuit say for 16 turnouts, all of a sudden the initial inrush would be about 8 Amps. One now needs a much heftier power supply than would be needed for normal operations, when it is unlikely that more than 4 turnouts would ever be activated simultaneously.
     
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  7. Hardcoaler

    Hardcoaler TrainBoard Member

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    I had the exact same concerns as you and all worked out fine with 22+ Kato turnouts on my railroad. I built a similar circuit (as shown below), adding a diode on the suggestion of someone to perhaps subdue a cascade of current that might accidentally throw additional turnouts after one is thrown. (There was uncertainty about the need for the diode; I added it as insurance). I drive the circuits with a simple solid state 12 VDC 3 Amp power supply, but I doubt that much amperage is needed. No capacitors show on the circuit photo because I was short of space inside my control panel. I mounted the caps near the turnouts.

    I apologize for the mess that you see here; please ignore my chicken scratch notes. I'm not an EE. :oops:

    DSN RR Kato Turnout Control Circuit - for upload.jpg
    2019-02-11 002 DS&N Turnout Control Panel - for upload.jpg

    2019-02-11 001 DS&N Turnout Control Panel - for upload.jpg
     
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  8. CSX Robert

    CSX Robert TrainBoard Member

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    While the initial current can be a concern with many turnouts, here are some things to consider: First of all, the initial surge is very brief and many power supplies will handle much more than their rated current for a brief period. Also, when first powered up, the circuit only draws that surge if the switch controlling it is switch to +V, if it is switched to ground, it won't draw a current until you throw that turnout. You can reduce the likely initial current draw by making sure any turnouts that have a "typical" setting use the ground side of the switch for that setting, increasing the likelihood those switches wouldn't draw current at power up. If it's still a concern, you could have a standard procedure of switching all switches to the ground position before powering up, or you could have additional power switches and power up the controls in banks.
     
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  9. Hardcoaler

    Hardcoaler TrainBoard Member

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    That's good information; something I never thought of before. I've seen some circuits for single-coil switch machines that have two capacitors, but I never messed with those. I now understand that they'd draw more current at start up. I suppose they're best when many quick throws are needed.

    While I'm thinking of it @SpacemanSpiff, if you install a Kato 20210 Double Crossover, it contains four turnouts and you'll need a 4700 MFD capacitor on its circuit.
     
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  10. SpacemanSpiff

    SpacemanSpiff New Member

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    I like your modification of using a DPDT so that the LEDs can use a single resistor. It's not much, but every bit helps. Sitwell's LED setup with a bipoloar LED is neat, but only if space on the control panel is at such a premium that one LED is better than two.

    It is good information to know that your setup works. Like @CSXRobert said, most power supplies probably can handle the initial surge; your experience serves as confirmation, which is what I was looking for. Yes, obviously if a particular switch is handling more than one turnout, like the Double Crossover, then the cap would have to be bigger.

    One other thing of note, in your setup, as well as Stilwell's non-LED setup, when power is shut down to the system the capacitors will retain charge. (In Stilwell's LED setup, the LEDs serve to bleed the charge I think) No harm in the charge retention, but something to be aware of, if servicing the system, as it could lead to a short and potentially damage the capacitor.

    Thank you for posting the pictures. They clearly show the advantage of this (and other) homegrown methods over the Kato controller. I can't imagine having a line of 22 Kato controllers. What a nightmare that would be.
     
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  11. SpacemanSpiff

    SpacemanSpiff New Member

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    @Hardcoaler, what is the power supply you are using?
     
  12. Hardcoaler

    Hardcoaler TrainBoard Member

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    I bought something that looks like the one here. I bought mine from All Electronics, but I just now find that they permanently closed up in late September. These should be easy to find elsewhere at ~ $10.

    upload_2024-1-22_18-20-7.png
     

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