Tilt/movement switch question

B

Bob

Guest
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.
 
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.
"Bob" <noemail@noemail.com> wrote in message
news:Xns94CDD1FF3AF29p34208fsd442@204.127.199.17...
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.
Click to expand...
 
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...
--
Paul Honigmann
 
Accelerometers are popular with microcontroller crowds...but definately not
cheaper than $2!

Analog devices is one company

Do a google for MEMSIC
"Nemo" <Paul@nospam.nospam.nospam.nospam.co.uk> wrote in message
news:WhflJxAxqSgAFwaY@furfur.demon.co.uk...
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...
--
Paul Honigmann
Click to expand...
 
"Bob" <noemail@noemail.com> wrote in message
news:Xns94CDD1FF3AF29p34208fsd442@204.127.199.17...
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.
Click to expand...
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
 
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

"Robert C Monsen" <rcsurname@comcast.net> wrote in message
news:DWcgc.159341$K91.412211@attbi_s02...
"Bob" <noemail@noemail.com> wrote in message
news:Xns94CDD1FF3AF29p34208fsd442@204.127.199.17...
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
Click to expand...
 
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.

The other requirement, it's gotta be cheap, hopefully under $2 even
as a onesy twosey.
Click to expand...
Use a spring from an used up ball point pen or something similar.

Solder (or better bolt) one end to a PCB and put a small nut in the free
end to make it more sensitive to motion.

A metalcylinder or -ring of sorts, eg. a piece of brass tubing or some
tinned copper wire should encircle the nut with some free play.


| PCB
|
|
|\
_|-------------_---
|_| |_| Nut
Bolt |_|/////(((((((|_|(() Spring
|_| |_|
|-----------------
|/
| \
| Solder the tube

Remember to isolate the tube from the spring :)

To increase sensitivity, stretch the spring (a bit at a time, don't
overdo it).

Price: Some rubbish from the junkbox.


--
Regards,
Soeren

* If it puzzles you dear... Reverse engineer *
 
On Sat, 17 Apr 2004 20:58:13 +0000 (UTC), Soeren
<Look@iNO-SPAMt.dk.invalid> wrote:

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.

The other requirement, it's gotta be cheap, hopefully under $2 even
as a onesy twosey.

Use a spring from an used up ball point pen or something similar.

Solder (or better bolt) one end to a PCB and put a small nut in the free
end to make it more sensitive to motion.

A metalcylinder or -ring of sorts, eg. a piece of brass tubing or some
tinned copper wire should encircle the nut with some free play.


| PCB
|
|
|\
_|-------------_---
|_| |_| Nut
Bolt |_|/////(((((((|_|(() Spring
|_| |_|
|-----------------
|/
| \
| Solder the tube

Remember to isolate the tube from the spring :)

To increase sensitivity, stretch the spring (a bit at a time, don't
overdo it).

Price: Some rubbish from the junkbox.
Click to expand...
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.
 
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.
 
Hi,

shb*NO*SPAM*@comporium.net (Si Ballenger) wrote in
news:4081c076.536616744@news.comporium.net:

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.
Click to expand...
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).


--
Regards,
Soeren

* If it puzzles you dear... Reverse engineer *
 
You must log in or register to reply here.

Welcome to EDABoard.com

Sponsor

Back
Top