# Tilt/movement switch question

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#### Bob

Jan 1, 1970
0
Looking for a small switch that will detect if the device it's mounted on
is tumbled. Not really a tilt, because the orientation after tumbling is
not anything I can count on, so if it's normally open, I need it to open
again after a momentary close (bouncing is ok). I'm thinking of some kind
of metal film connected as common that can bend back and forth between two
possible contacts.

The other requirement, it's gotta be cheap, hopefully under $2 even as a onesy twosey. Thanks. A #### Art Jan 1, 1970 0 Most I've seen are non-reset used to sense if an LCD or Plasma unit has been subjected to a non-upright position is shipping. These devices respond to a specific angle beyond horizontally plumb. The only thing that I could invision sensing that effect and resetting would be some type of liquid switch or maybe a microswtch with a "loaded" trigger arm attached to it. One that will react to gravity vs position. May want to search Google or Yahoo. N #### Nemo Jan 1, 1970 0 There are various tilt switches that may work. The old ones used a blob of mercury. Modern ones use a ball bearing inside. Just look for "tilt switches" in your favourite electronics supply catalogue... S #### SB Jan 1, 1970 0 Accelerometers are popular with microcontroller crowds...but definately not cheaper than$2!

Analog devices is one company

R

#### Robert C Monsen

Jan 1, 1970
0
Bob said:
Looking for a small switch that will detect if the device it's mounted on
is tumbled. Not really a tilt, because the orientation after tumbling is
not anything I can count on, so if it's normally open, I need it to open
again after a momentary close (bouncing is ok). I'm thinking of some kind
of metal film connected as common that can bend back and forth between two
possible contacts.

The other requirement, it's gotta be cheap, hopefully under $2 even as a onesy twosey. Thanks. I just bought some piezo-gyros from a guy on Ebay. They were$20 apiece, but
they might fit the bill. Any rotational acceleration along their main axis
will perturb a voltage output, one way it goes down, the other way it goes
up. I got a set of three for $60. If you hook up a couple of comparators as a window detection circuit, and it'll trigger if you tumble faster than a certain speed. You need three to get an accurate picture of three dimensional rotation, of course. They are used in camcorders, I believe, for stabilization. There are also accelerometer chips, which may not tell you when the rotation is occuring, but which can detect the direction of gravity when the system is motionless. I was just looking at a two axis one from analog for around$20 ( from digikey. ) Type 'accelerometer' into the digikey search page.

Regards,
Bob Monsen

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#### SB

Jan 1, 1970
0
The accelerometer chips indicate movement with respect to gravity.
The ADXL210 from Analog Devices outputs a 50% duty cycle square wave when
it's sitting still (at 1G). As it moves in either direction, the ducty
cycle changes (lessens for one direction and increases in the other). Their
devices max out for each model (the 210 is good up to 10G's).

I have one mounted on a radar dish and through mistakes of my own I didn't
get it square on the PCB or in the box or on the mounting strut! So I have
a constant offset from it's 50% duty cycle. Not a big deal to fix with
microprocessors!

You can get a measuring cycle of 1mS which is good for vibrations. You
could code your microprocessor to give velocity as well....since you are
moving at a constant speed, the accelerometer will show a likewise
deflection depending on your speed (faster you go...the more the
deflection).

Check out Basic Stamps for a really easy microprocessor to use!
www.parallax.com

sb

S

#### Soeren

Jan 1, 1970
0
Hi Bob,

Looking for a small switch that will detect if the device it's
mounted on is tumbled. Not really a tilt, because the orientation
after tumbling is not anything I can count on, so if it's normally
open, I need it to open again after a momentary close (bouncing is
ok). I'm thinking of some kind of metal film connected as common
that can bend back and forth between two possible contacts.

tilt situations.

M

#### Matt J. McCullar

Jan 1, 1970
0
For years pinball machines used a heavy plumb bob on the end of a long metal
rod; encircling that rod was a metal collar. During normal play the metal
rod would not touch the collar that surrounded it. But if somebody tilted
the machine, the rod would touch the collar, and the TILT circuit would
close.

S

#### Soeren

Jan 1, 1970
0
Hi,

shb*NO*SPAM*@comporium.net (Si Ballenger) wrote in
I got a couple of blinking LED toys (a ball and a dice) at the
DollarTree store that have the spring type of shock sensors in
them for \$1 each. Spring type of sensors work more on shock than
tilt situations.

Yes, they can be used that way too, it is all a matter of selecting the
right spring and weight.
I have med sensors so sensitive that you would trigger it by just thinking
about moving the pieces of equipment they are in

(That would be highly impractical in your ball and dice, so there it is
made much less sensitive of course).

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