Tilt Sensor Tutorial

What is a tilt sensor?

Tilt sensors allow you to detect orientation or inclination. They are small, inexpensive, low-power and easy-to-use. If used properly, they will not wear out. Their simplicity makes them popular for toys, gadgets and appliances. Sometimes they are referred to as "mercury switches", "tilt switches" or "rolling ball sensors" for obvious reasons.

They are usually made by a cavity of some sort (cylindrical is popular, although not always) and a conductive free mass inside, such as a blob of mercury or rolling ball. One end of the cavity has two conductive elements (poles). When the sensor is oriented so that that end is downwards, the mass rolls onto the poles and shorts them, acting as a switch throw.

Tilt switches used to be made exclusively of mercury, but are rarer now since they are recognized as being extremely toxic. The benefits of mercury is that the blob is dense enough that it doesn't bounce and so the switch isn't susceptible to vibrations. On the other hand, ball-type sensors are easy to make, wont shatter, and pose no risk of pollution.

While not as precise or flexible as a full accelerometer, tilt switches can detect motion or orientation simply. Another benefit to them is that the big ones can switch power on their own. Accelerometers, on the other hand, output digital or analog voltage that must then be analyzed with extra circuitry.

Basic Stats

These stats are for the tilt sensor in the Adafruit shop which is very much like the 107-2006-EV. Nearly all will have slightly different sizes & specifications, although they all pretty much work the same. If there's a datasheet, you'll want to refer to it

Size: Cylindrical, 4mm (0.16") diameter & 12mm (0.45") long.
Price: $2.00 at the Adafruit shop
Sensitivity range: > +-15 degrees
Lifetime: 50,000+ cycles (switches)
Power supply: Up to 24V, switching less than 5mA
Datasheet

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Step 1: Testing your tilt

Testing your sensor is simple. Put your multimeter into continuity-test mode and touch the probes to the two leads. Then tilt to determine the angle at which the switch opens and closes.

vincentmcmurray says: Oct 7, 2012. 2:32 PM

If i stick one of those tiny buzzers and a secret switch in series instead of the Led i'd have a great alarm system for the bike. It would have to be on its side stand though ?

Vick Jr says: Jan 16, 2011. 10:46 AM

Can this internal pull-up resistor trick be used for other sensors, such as the PIR motion sensor?

thedod says: Dec 5, 2010. 9:21 PM

Me again. Tried the internal pul-up resistor trick (on a freeduino) and it didn't work :(
I wonder: does it work on specific Arduini?

thedod says: Nov 30, 2010. 11:35 AM

Thanks. Especially for the tip about the internal pull-up resistor.
Off topic: the wave shield video is brilliant.

duxes says: Jul 7, 2010. 7:39 AM

Any one has got idea about mechanical tilt sensor which can be used in outdoor?? I need some info for my antenna tilt sensor project.. plz help me....