Kato Unitrack Turnout Control with Capacitive Discharge Power Supply Question

Hardcoaler Feb 21, 2018

  1. Hardcoaler

    Hardcoaler TrainBoard Member

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    I plan to build samples of both the George Stilwell BCD Circuit and the Rob Paisley Circuit to choose which I like best to control the Kato Unitrack (single coil) turnouts on the N Scale layout I am planning. These are capacitive discharge circuits, neither with transistors. I'll be driving 24 Turnouts.

    Both circuits require 12 VDC, but I have two choices for power sources and need help deciding which is best. Can someone help me decide?

    One option is a 12 VDC 500 mA "wall wart" transformer which I have. With no load, it produces 16 VDC. I'm thinking that it's probably unfiltered and will need an inexpensive 470uf electrolytic capacitor added to the output.

    The other option is a Hewlett-Packard printer 18 VDC 1.1 Amp power supply which I have. With no load, it produces 18.5 VDC and I assume it produces "clean", filtered power. I'd then connect its output to a "buck converter" that I'd need to buy to get the needed 12 VDC.

    Which is my best bet for circuit longevity and reliability? I know that when these two sources are connected to a load, the output voltage will drop. I'm thinking that the H-P/Buck Converter choice might be best, but it also might be overkill for such relatively simple circuits. Any advice is appreciated!
     
  2. wvgca

    wvgca TrainBoard Member

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    the cheaper option would rise [eventually] to 16v, so would there be much difference between the two ???
    just a little over two volts difference , either way is slightly overkill to my thinking
     
  3. Hardcoaler

    Hardcoaler TrainBoard Member

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    True. I'm just not sure if twice the amperage with the H-P/Buck Converter matters. Probably not.
     
  4. Jimbo20

    Jimbo20 TrainBoard Member

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    You could put the Buck convertor on the 12V wall wart, which would help regulate its output....
     
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  5. wvgca

    wvgca TrainBoard Member

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    an increase in current will speed up the cycle time, this can be monitored by a zener diode / led on the output of the capacitor, a higer voltage will give more 'snap' to the throw
     
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