Introduction: How to Make Simple "motion" Sensors

Picture of How to Make Simple "motion" Sensors

Well, sometimes we need to switch something by position change or movement... It is easier than you thought!!!! I am going to cover 2 kinds of "motion" sensors in this instructable.

The first one is a ball-based vibration detector. It detects any kind of movement. It's only disadvantage is that the contact time is really short at this sensor, so you have to connect it to a very sensitive circuit or prolong the signal length by a programmed PIC, somehow like Xyzzy did in his DIY RumblePak for Nintendo DS.

The second one is a tilt sensor (well, it is ball-based, too). This is the sensor used in my other project, home-made Guitar Hero controller. It is very simple and still quite effective!!!

Step 1: First Type - Components Needed

Picture of First Type - Components Needed

So you gonna' need the following components:

- a piece of thicker and harder copper wire
- a spring (e.g. from a pen)
- an iron ball (e.g. from a ball bearing system) - of course proportional to the other components
- soldering-iron and some solder
- and of course a bit of hot glue

So here it is how it worx:

The spring starts to move (or rather vibrate) because of the mass of the ball (you know, the friggin' inertial force _). If the movement is big enough, the ball makes contact with the copper wire (both physically and electrically).

Step 2: First Type - Construction

Picture of First Type - Construction

You need to solder the ball and the spring together like you can see it on the picture. Then solder a piece of the hard copper wire (from the mentioned one) to the other side of the spring. Next you need to make a circle at the end of the remaining wire - the bigger the circle the less sensitive will the sensor be (but maintain the proportions - or position the spring correctly). You can also set the sensitivity of the sensor by shortening the spring (or by stabilizing the root of the spring - e.g. by soldering). I know it is a little bit hard to tune it properly for your needs, but it is possible.

Step 3: First Type - Done!!

Picture of First Type - Done!!

Now you need to solder 2 wires to the 2 separate parts of the sensor. After that glue them together as seen on the picture. Warning! Don't let the two wires make contact nowhere - the only place where it can make contact is the upper part - the ball and the copper circle!

And voila, it's done! Enjoy! For the next one go to the next step!

Step 4: Second Type - Components Needed

Picture of Second Type - Components Needed

You need the following components:

- 2 pieces of thick copper wire
- copper tube (our tube was chromed - harder to solder)
- an iron ball (e.g. from a ball bearing system) - of course it must fit to the tube
- soldering-iron and some solder
- a bit of hot glue

How it worx?

As you change the position of the sensor (a few degrees from horizontal) the ball rolls to one side of the tube (that damned gravity... _) and if it's the side where the central contact is (made from the wire), the ball makes electrical contact between the tube and the wire - and that's it!

Step 5: Second Type - Construction

Picture of Second Type - Construction

Place the ball to the tube and make sure it won't fall out from on side of it (glue, solder or plug there something - or hit it with a smaller hammer). My tube was cut in a way that it wasn't an issue. Remove the insulation from the ends of the 1st wire then make small circle on one end. Then make a shape from the whole wire according to the shape of the tube (as seen on the 2nd pic). It will hold itself in place. Place it on the tube (like on the 3rd pic) - you know, the small circle must be on the side which is not plugged... Make sure there is no el. contact between the copper wire and the tube. Glue it the wire to the tube as it is now.

Step 6: Second Type - Done!!

Picture of Second Type - Done!!

Wrap the second copper wire around the tube (see the pic). To make a better el. contact, solder it to the tube. If yours is chromed too, scratch the soldering place of the tube a little bit with a Stanley knife and try to solder it after that. In the end, hot-glue it a bit and it's done! Enjoy! it works very well as the sensor of the Guitar Hero controller.


TamilHagilan (author)2017-08-08

How does i supposed to connect it with my arduino board.... The normal one have 3 pins but this one have 2 pins only..... If anyone have any idea...pls email me on Thank you....

Anisya (author)2016-10-21

hi there, school project is my project gonna be a math mechanical compasses where they can draw and measure the angle at once.. can I use sensor? how can I do it?

Cboy1100 (author)2016-04-09

stupid question...I have a h20 dispenser and it's in a dark corner, I can't tell when my cup is full. I'm not blind and the finger in the cup sucks, well I'm visual. I need a small,tiny light that wakes up when I get to the handle and shuts of when I'm way. I think I can do this for under a 1$.... oh don't tell me to flip on the light switch,ill reach out...I'm in a dark room where my eyes,and others are adjusted to the movie,game etc..and when you look away your blind..having a light pop on at waist level would help stop stupid...and stop any problems in the dark. Thomas ty

ArifSae (author)2016-03-09

Thank you , helped me in making something similar, with slight different approach.

raralorgat04 (author)2016-01-10

do you know how to make a sensor that senses things coming close

ArifSae (author)raralorgat042016-03-09

this might be helpful to what you are asking

ArifSae (author)ArifSae2016-03-09

or better

raralorgat04 (author)2016-01-10

do you know how to make a sensor that senses things coming close

AshwinV4 (author)2015-11-12


ceasar.barrera (author)2014-11-19

Hey man, that's a cool tip thank you. Now is there anyway you can use this sensor to pick up wind speed and convert it to a digital relay? To show the wind speed digitally? Now we have a weather station with your standard anemometer, but it keeps breaking. I work in Prudhoe Bay, Alaska and the high wind speed tear the damn thing apart, do you have any solutions?

dentsinger (author)2014-05-22

Very nice. You can make the first switch more sensitive by stretching out the spring a little so the the mass of the ball reacts more. Kinda makes me think of a switch similar to a mercury switch whereby you don't need mercury. Using a drinking straw, and a bb. Insert your leads into the end of the drinking straw, melt with a lighter and then clamp the end with pliers. A clear drinking straw would be best. Insert your ball bearing into the other end and burn and clamp it in. You now have a switch like a mercury switch.

Bilal Cena (author)2013-09-20

I like the first sensor. Thought Ill like to know HOW it exactly works

Meaning like is this an alarm type of thingy? When there is a motion it (the spring and the ball) would make a buzzing kind of sound?

Also where does the two wires go?? Some information on this would be very very helpful. Thank You

ajanevski (author)2013-03-23

where we should put outlet wires ?? :D

joeny1980 (author)2012-11-26

perfect! I was looking for a way to make a motion sensitive switch for a bird toy. Your version 1 is perfect.

joeny1980 (author)joeny19802012-11-26

By the way I just found the ball bearing that is the perfect size and a nice weight, from the inside of a paint marker. Its a ball thats in the ink cavity to help mix when you shake the pen. Also, to adjust sensitivity, I suggest trying different pens. I was surprised that there was a nice range of spring sensitivity in all different pens I tried. I am going to likely further use the ballpoint pen to build the switch inside of it. This should work perfectly.

Aplonis (author)2011-11-13

Congratulations! You have almost exactly re-invented the firing switch for a US Navy Mk 37 electric torpedo.

smarterthanu (author)2007-07-27

You forgot the most important part of a sensor - its (digital computer) interface.

servant74 (author)smarterthanu2007-07-27

put a resister on the end of one of the wires, (try 220 ohm), and connect it to a data pin on your parallel port. the other end of the device needs to be connected to either ground or +5v depending on what you want to do. Or get a basic stamp, use the diagrams from Parallax on interfacing it, and the Stamp can do your de-bouncing and change it to a USB or serial device easily. Check your manufacturer for the specs on your parallel port. This kind of thing works well with my Altair8800 using my Processor Technology 3P+S board as the interface! :)

DIY-Guy (author)servant742011-10-22

Altair!? I acknowledge the superiority of your historical hardware collection!

(Now where did I box up my Vic-20 with cassette tape storage and ... 300 baud modem?)

qwefad1453 (author)2011-05-08

would it be able to hook up to an alarm type thing?

lingeriliu (author)2009-12-02

 really do keep in mind the KISS engineering rule hehe

fisherblue23 (author)lingeriliu2010-12-30

Kiss= (K)eep (I)t (S)imple (S)tupid

wactac (author)2009-08-08

Simply genius!

osama_ (author)2009-04-20


canno (author)2009-04-12

this is just an idea off the top of my head: just put a piece of wire or conductive material on the bottom corner of the door like in this shape ] and have like 2 ends on the wall or frame so when the doors swings open, the 2 points will connect add a buzzer kinda thing so that when the two parts connect, it makes a short buzzer noise 4/5 good instructable didn't include the batteries nor what you put to know that the sensors worked

edfel01 (author)2008-02-16

looks awome i am going to try it if i have metal ball right now. do i have to solder? can i use electric tape?

gman2000watts (author)edfel012009-02-08

you don't wanna use electric tape because the circuit won't close, if you don't wanna solder try hot gluing the bottom of the ball, but not too much to where it covers up the sides.

bluestripe (author)2008-08-05

what would the motion sensors trigger

wolfy02 (author)bluestripe2009-01-29

at my previous job they triggered cores to run in and out on trim dies making cylinders for Poulan Chainsaws. Those "Go" switches as some called them, ranged anywhere from $70-130+ Could use this on a garage door so when it closes it turns on the garage light for you, or even turns on your house if you've got a smarthouse hooked up.

amando96 (author)bluestripe2009-01-29

what ever you want i guess...

looking4ideas (author)bluestripe2008-09-23

A bomb

omnibot (author)looking4ideas2009-01-28

What?!? NO!! They would trigger the apocalypse plain and simple.

godfreyandthandi (author)2008-08-28

great but these sense motion? or touch?

GalaxyX (author)godfreyandthandi2009-01-01

they would sense both although for motion there has to be either a giant motion sensor or a giant person in the room that is high on red bull and jumping like a maniac. but it would still work

robokid (author)2008-03-22

;o interesting kinda hard u need to Simplify it but iz realy good

MayolaTikaka2 (author)2008-02-03

great info I'd like to now you wats ur group

chacho5 (author)2008-01-14

so exactly where to the wires need to be soldered on? I know that one is soldered to the big wire but where does the other one go? maybe put another pic on there or somethin. And why the heck do you need glue?

Gmastefluffy (author)2007-08-01

You could probably do something similar to what you already have now but with mercury as a trigger

teebee918 (author)Gmastefluffy2007-08-02

I was thinking about that too, but you know the mercury is highly poisonous to inhale, and it evaporates, so it is really important to trap the mercury hermetically. Of course, it would be much more sensitive - much better working, but kinda dangerous.

dentsinger (author)teebee9182007-10-04

Radio Shack used to sell mercury switches. I guess increased paranoia has changed everything.

whiteoakart (author)2007-08-05

This is great. A nice simple device. I will use this on my Leprechaun Trap. Next March I expect to have a real leprechaun to show all of you, now that I have the trigger mech.

teebee918 (author)whiteoakart2007-08-06

I'm looking forward to it! Let me know about it, when it's done!

Bikemechanicwannabe (author)2007-08-03

would this work if i attached it to an alarm system? im trying to develop an alarm system for bikes (i know, i know.. it might be a tad be useless)

The first one would be ideal for that purpose, but you should make a good interface for that first.

Yerboogieman (author)2007-08-01

thats really kool, now make something that can shock someone, lol

dfc849 (author)2007-07-30

great instructable! i think the second type (or similar) is used in the Xbox 360 to tell it how to use the RoL controller setup

teebee918 (author)dfc8492007-07-30

Thanx! Maybe, i don't know. I guess you're right. I have used it as the tilt sensor in the GH controller for PS2 - you know, it activates star power... Check out my other instructable...

dfc849 (author)teebee9182007-07-30

I saw that. I have actually broken 2 GH2 controllers and just bought one wireless one, have four PS1 (1 with analog sticks 3 without) controllers that need salvaged. that will help for at least one more guitar. Kudos on both Instructables, teebee!!!

teebee918 (author)dfc8492007-07-30

Thanx! I was glad to help!

kreeningsons (author)2007-07-28

I used to make these sometimes, but I wouldn't say they sense motion, since they can't sense if another object is moving (but, for example, an infrared device could detect movement in this sense). I think it would be better to say they sense vibration.

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