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Grounding Smail switch machines

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  • Member since
    August, 2017
  • 3 posts
Grounding Smail switch machines
Posted by Gary Morton on Thursday, August 03, 2017 9:23 AM

Hi folks . . .

Newbie here, to the forum and the hobby (actually I'm belatedly reviving a childhood hobby). 

I've purchased some Smail switch machines. As most of you probably know, these are basically Tortoise machines win onboard DCC decoders. They can be operated from the cab, but they also have connections for manual operation via panel switches, which I'd like to install.

There are three solder pads on the Smail board labeled C1, GND, and C2. Wires are run from C1 and C2 to the two sides of a ON-OFF-ON momentary toggle switch, which connects one lead or the other to ground. The GND pad on the Smail is wired to the center terminal on the 3-pin switch, according to the diagram on the Smail instruction sheet.

My question is, Does the GND wire need to connect somewhere to actual earth ground? If it does, where and how is that connection made? If it does not, in what sense is it grounded?

I'm using a Digitrax Evolution DCC system. The DCS210 command station has a front panel terminal for GND, but it is not clear to me to what THAT should be connected. Should the ground wire from the Smail and toggle continue on and connect to that terminal? That terminal, however, is not connected to earth ground either --- the barrel plug from the PS615 LOOKS like it has only 2 conductors.

???

Thanks for any help!

 

  • Member since
    February, 2002
  • From: Reading, PA
  • 23,094 posts
Posted by rrinker on Thursday, August 03, 2017 11:12 AM

 No, the only connectiosn to the Smail would be the momentary toggle (or pushbuttons) between the C1, C2, and GND. Nothing else needs to connect to the GND terminal.

 More of confusing arising from the somewhat generic use of GND or Ground in the US - it is in this case not earth ground, it is COMMON. Internally in the circuit of the Smail it's probably just the same as the - side of the power supply. So one side of your switch to C1, the other side to C2, and the center common terminal to the GND pad.

                   --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
    August, 2017
  • 3 posts
Posted by Gary Morton on Thursday, August 03, 2017 9:40 PM

Thx Randy. That helps!

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