how much distance can a switch be to the prop 1

[werf]

I am doing some planning for next year, I want to trigger a prop1 with an industrial style limit switch. I am wondering how far away I can be before I need to run the trigger through a relay. Any idea in feet, 10, 50 100? I guess I could do a voltage drop calculation for wire size but thought a general answer may be out there.

[bsnut]

To answer your question,18 gauge you may get 50 feet. But its hard to say for sure without a little experimentation with some wire or doing the calculation for voltage drop. But your best bet is to use a relay as the trigger, that way you can go the extra 50 feet and don't have to worry about the wire size at all.

[JonnyMac]

As you correctly point out you can calculate the voltage drop (2x the distance between the controller and the switch). Good design suggests not dropping more that 10% so you'd want to calculate the size for no more than a 0.5v drop to the controller. 

Here's the rub: If you're going to use a long wire like this it is going to become an antenna connected to the controller and you will be subjecting your trigger code to all sorts of noise created by nearby RF sources. I was helping a haunt in NY a few years ago that was having all sort of self-starting problems.  They were using trigger code like this:

Main:
  IF Trigger = IsOff THEN Main

...which is okay for a button on the board, but no with a connection through wires.  This is why we developed the standard code we use today which looks like this:

Main:
  timer = 0                                     ' reset debounce timer

Check_Trigger:
  PAUSE 5                                       ' scan delay
  IF Trigger = TrOff THEN Main                  ' check trigger input
    timer = timer + 5                           ' update timer
  IF timer < 100 THEN Check_Trigger             ' check timer

This will prevent spurious inputs from RF sources (radios and cell phones) from creating false positives.

[JonnyMac]

BTW... I was working with a haunt all weekend ("The House of Restless Spirits" in Santa Monica) and we needed to to a quick check on voltage drop. I have an Android phone and one of my favorite apps is called ElectroDroid. If you have an Android phone it's a great app for it.

https://play.google.com/store/apps/details?id=it.android.demi.elettronica&hl=en

I have no affiliation with the creator of this app -- I downloaded it, tried it, and like it.