I am currently collecting stuff for a track inspection car I plan on building. I am going to use some old mercury switches (yew I am aware of the taboos) to light indicator lights for side to side out of level and grade percentage in 1/2 degree increments.
My question is: Is there a digital equivalent to an old time thermostat mercury switch? And can it be had for less than an arm or leg?
Bob C.
I-phone. I bet there’s an app for use as a carpenter’s level.
Bob - you can use a pendulum hanging from the shaft of a potentiometer that will swing from side to side or front to back based on level.
I have built such sensors but would suggest a digital level - here is a list from Google
I have several, including one from MicroMart and one from Harbor Freight, and they work very well.
dave
But a digital level wont give an indication that can seen from a distance. The problem with a pendulum, is that movement of the train could give a false indication of out of level.
The digital level I use beeps when out of level and beeps more frequently when getting closer to level and goes to a continuous tone when level.
Should work.
Greg
From the replies I see I have not been clear in what I am looking for. I have considered the level, but am not (hopefully) looking to spend that much. More what I am looking for is a digital component that would effectively replace a mercury switch. Something that in the future I could replace the mercury switches to remove that particular hazard.
The intent is to be able to as slow speed, push the car around the layout (club’s layout is something in the order of 1200 feet) and be able to mark the bad spots as we go. The current method of eyeball and torpedo level is awfully time consuming, and does not get all the spots, or the duration of the location. I guess the intent is to make the car a dynamic rather than static device.
I am sure the iPhone has a device that is being read and the software within provides the reading. As for cost effectiveness, several iPhones would absolutely break the budget for this project.
Greg, is your level less than 3.50 inches in length? I am trying to keep this within or less than car width.
Bob C.
Modern trailer brake controllers contain a component that senses vehicle attitude; acceleration and deceleration rates. I don’t recall what it is called; maybe an accelerometer? In any case; its a small digital device that can be used by software to determine attitude. - So yes; the part you seek is out there, but you’ll need someone more in tune with modern electronics than me to help you make it work 
Here is a low cost digital solution. You still need to process the data and display the results.
http://www.pololu.com/product/2129
Here is a high cost digital solution that does all of the complex processing for you. You still need to display the results.
http://www.pololu.com/product/2723
Bob
Bob Cope said:
My question is: Is there a digital equivalent to an old time thermostat mercury switch? And can it be had for less than an arm or leg?
Bob C.
They have 15, 30, and 45 degrees for under $2.
http://www.goldmine-elec-products.com/prodinfo.asp?number=G16882
Bob and Jon,
Thanks, that is what I was looking for in function. Way over the price point I am looking at this time. I will bookmark the page though for future reference. I have sufficient mercury switches to build a couple of the cars if I wanted to, so I will keep them for spares (hope I never need them).
Twenty bucks for the basic chip isn’t bed, but by the time I get it finished it will be way over budget.
Bob C.
Bob, I think mine is 10" but the guts are in the center, saw the ends off and put it crosswise for side to side level.
Greg