# Electronic Spirit Level for 5th wheel

#### RobbJohnson

Joined Dec 15, 2009
76
I am looking to replace my large bubble level on the front of my fifth wheel trailer. It is large so you can see it in the rear view mirror. It is calibrated to show if the wheels (left and right) which are 96" apart are out of level by 1-1/2" or 3", this is so you know how many 2*4's to put under the low wheel.

I would like to use LEDs and a micro-controller to do this. my concern is what to use for the leveling I.C.
it seems to me it should be a single axis gyro, but I see that 3 axis accelerometers will do this to, (must have a static mode)?

Would appreciate any help or comments.
Thanks, Robb

#### KMoffett

Joined Dec 19, 2007
2,765
I don't think electronic gyro or accelerometers will do what you want. Maybe a potentiometer with a pendulum arm, feeding an LM3914 LED bar/dot display or a microcontroller to an LED display.

Ken

#### KMoffett

Joined Dec 19, 2007
2,765
Then you want to search for "inclinometer"...generally not cheap.

Ken

#### ifixit

Joined Nov 20, 2008
650
My iphone 4s has a compass app that does a levelling function when you put the phone on its edge. Maybe you could somehow use that for levelling your trailer... if you have an extra iphone.

What device are they using in a phone for levelling? The things they put in phones today.

Ifixit

#### DNA Robotics

Joined Jun 13, 2014
494

#### jpanhalt

Joined Jan 18, 2008
7,691
Sears sells a torpedo level for $32 list (http://www.sears.com/craftsman-digital-torpedo-level/p-00948295000P?sid=IDx01192011x000001&kpid=00948295000&kispla=00948295000P&kpid=00948295000&mktRedirect=y ) I got one of those for about$25 without the laser a few years back. It is quite sensitive. I harvested the accelerator from it (Memsic MXD2020). It is quite sensitive and ±0.5° around level is easy to attain. Noise at rest is less than ±0.2°. I am currently using that sensor in a remote leveling device, which uses an XBee transmitter/receiver for a serial link.

The MXD2020 (100 Hz version) is a bit difficult to source, but it has nice specifications.

John

#### Lestraveled

Joined May 19, 2014
1,943
I like KMoffetts suggestion of a potentiometer and a pendulum. You can easily scale the output to display inches. You could use a DVM or put in a digital panel meter to display your info.

#### RobbJohnson

Joined Dec 15, 2009
76
I have ordered some mma7361 3 axis accel. I will post my results.

#### RobbJohnson

Joined Dec 15, 2009
76
prototype is working well. simple circuit. just used the a to d converter in the micro and turned on leds.
working on the packaging now.

#### Bernard

Joined Aug 7, 2008
5,227
Thanks for your report, we'r looking forward to final prt.