Introduction: Re-purposing an Air Wick Freshmatic Compact I-Motion

Picture of Re-purposing an Air Wick Freshmatic Compact I-Motion

The Air Wick Freshmatic Compact i-Motion air freshener is an intriguing target for re-purposing. It uses a passive infrared (PIR) sensor to detect motion in a room and then increases the rate that it dispenses air freshener. This air freshener sells for $8, but you can sometimes get it cheaper with coupons.

Radio Shack carries the Parallax PIR module for $10. So the question is why bother re-purposing the Air Wick air freshener?

If you just want to replicate the Parallax PIR module, you can modify the air freshener by drilling 2 holes, adding a wire, and cutting a trace. Stopping here, you end up with a can of air freshener, 3 batteries, 2 slide and 1 push button switches, a cool aerosol valve, a medium power PNP transistor, a two wire connector with leads, and a LED.  I will show you two ways to do this; the simplest way, and a way to make the module the smallest.

However, If you want to go a bit farther, you can access the amplified analog sensor output as well as the digital signal, and have an externally accessible relay driver, and LED. I describe how all of these features are brought out to an easy to interface connector. You still end up with the air freshener, batteries, switches, and cool aerosol valve.

This last approach is a little more complicated.


Step 1: Avoid the Competition

Picture of Avoid the Competition

Make sure that you start with the right product. Glade also makes a motion detector air freshener. It uses considerably different technology.

The Air Wick air freshener uses a PIR sensor. The fragrance canister nozzle is depressed when it is inserted into the air freshener. The fragrance is dispensed by a valve in the air freshener that is activated by a relay driver type circuit. The PIR will detect large movements to about 15 feet with the Fresnel lens attached.

The Glade air freshener uses a light level (shadow) detector and a motor and gear train to depress the canister nozzle and dispense the fragrance. The motion detection on this product has much shorter range than the Air Wick air freshener. It generally sells for $5. It has a nice Sanyo motor that runs on 3 volts.

Step 2: Opening It Up

Picture of Opening It Up

The photo below shows the parts of the air freshener after you defeat the security screws.

To defeat the security screws, make a driver from a piece of 1/8" steel rod. Grind one end to a triangular shape that fits the screws. The secondary photos below show the driver I made and one of the security screws.

There are 4 security screws holding the case together; 2 that can be seen from the back of the case and 2 inside the battery compartment.

Step 3: Approach 1: Digitized Sensor Output - Simplest Way

Picture of Approach 1: Digitized Sensor Output - Simplest Way

To just access the sensor's conditioned digital output, follow the steps below:

    1.  Using a #62 drill bit drill a hole through the circuit board from the copper side at
         the locations marked Sd and Jmp1 in the photo. The locations are indicated
         by a yellow dot. Both locations have a convenient little circular pad that
         we can use. If you can not find a #62 drill bit, see if your hardware store
         carries a #60, this will work. A drill bit especially made for PCB drilling
         works the best.

    2.  Cut the trace that is next to Jmp 1. You might have to click the "i" at the corner 
          of the photo to see the location clearly. 

    3.  Place a wire jumper on the non-copper side of the PCB between Sd and
         Jmp1 and solder.

    4.   Remove the switch from the black female connector's wires. The black
          male connector now has the conditioned digital sensor signal and ground.

Step 4: Aproach 1B: Digitized Sensor Output - Small Module

Picture of Aproach 1B: Digitized Sensor Output - Small Module

This approach is a little more complex than the previous one. We will cut the board to reduce the size of the module. We will have access to just the digitized sensor output.

   Note: If you cut the board down, you can not do the modifications to add external
              control to the relay driver and LED described later.

The Steps:

   1.   Flip the capacitor marked C11 so that it points towards the sensor. We are going to
         cut near where it originally lays.

   2.  Strip off the LED, medium power transistor, the large diode, switch SW2 next to 
        C11, and the black connector.

   3.  Drill a hole at the location Sd shown in the previous step's photo.

   4.  Add the two jumpers seen below in the photo.

   5.  Cut the board a little below the red connector. Sand the cut to make your cut
        smooth and straighten any woobles in your cut. You can sand right up to the
        edge of the red connector.

You now have access to the digitized sensor output at the outer pin of the white connector and a smaller module.         

The picture shows how I trimmed and attached the lens to the module with hot glue.

Step 5: Approach 2: Getting It All - Drilling the Holes

Picture of Approach 2: Getting It All - Drilling the Holes

In this approach, we will:

   1.  Add access to the amplified analog output to the PIR sensor.
   2.  Have external control to a relay driver.
   3.  Have external control to a green LED mounted on the module.
   4.  Bundle all the above into a nice 2x3 connector suitable for 
        easy interfacing to a microcontroller.

Drilling the holes for the additional access points:

   1.  Remove the multi-position switch (SW1) located in the lower right
        corner when the PCB is viewed from the non-copper side. If you
        want to salvage the other switch, remove it also at this time.

   2.  Using a #62 drill bit, drill holes at the locations shown in the secondary
        photo below. There are 11 holes. The spots are marked with yellow dots 
        in the photo. Take special care at the locations marked LED, R, c1
        and c2.
These locations do not have a circular pad that we can use.
       When drilling these locations, do not drill into the trace, but rather 
       next to the trace

  3.  At LED and R use a dental pick to scrape down to the trace through the
       protective overcoat. This overcoat will re-flow with the heat of the solder gun.
       Try to use the minimum amount of heat possible to make the connections.
       Always be aware of the surface mount components near where you are soldering.
       You need to approach the location so as not to accidentally heat them.      

Step 6: Cutting the Traces

Picture of Cutting the Traces

Cut the traces marked by the 5 yellow lines in the photo below. I used a dremel tool with a pointed bit. Cut into the epoxy for the cut near the hole marked "R".

Step 7: Bypassing C15

Picture of Bypassing C15

To gain the access to the medium power transistor's pre-amp we need to bypass the capacitor marked C15 on the PCB.

Place a piece of wire along the edge of C15 and use it to glob solder across the capacitor.

If the connection is correct you should see 10k ohms between the end of R10 closest to the drilled hole R and the base of the pre-amp transistor. You should also see 100k between the base and the emitter of the transistor (make sure to put the positive lead on the emitter).

Step 8: Preparing the Interface Connector

Picture of Preparing the Interface Connector

Our goal is to use the removed switch's contact pads to put in a 3x2 connector that will allow easy access to the module.

In the picture below you can see that all the holes are drilled and all the trace cuts have been made. If you look at the removed switch's pads you can see that 6 have been selected and the outer 4 of the six enlarged. This is because the switches pad to pad spacing is not the same as the connector. I used an #50 drill to enlarge these holes and you can see that I destroyed the pads. I should have used a smaller drill. If you can retain some portion of the pads, the soldering work is much easier. 

Step 9: Adding Jumpers and Soldering the Connections

Picture of Adding Jumpers and Soldering the Connections

On the traces next to the holes that are not on circular pads (R and LED) you need to expose the trace by scratching off the protective overcoat. I used a dental pick.

Next install jumpers across the non-copper side of the PCB jumpers as shown in the picture below. You can see my pin-out for the 2x3 connector drawn on the board. 
       A   =  PIR ampified analog sensor output
       D   =  Digitized PIR sensor output
       R   =  Input of relay driver pre-amp
       L   =   LED cathode through resistor (connect to gnd to light LED)
       V   =   Vcc
       G  =    gnd

Use your multimeter to make continuity checks as you go along. Mine actually went together quite easily. Remember to try to use the minimum of heat and keep away from the surface mounted components and you should have no problems.


Step 10: Testing

Picture of Testing

When you are finished you can make a few tests to make sure that everything is ok.

Connect Vcc and gnd either through the red connector or on the Vcc/gnd
pins of the 2x3 connector.


1. Insert a female connector with wires into the black socket. Touch the two
    wires together. The green LED on the module should light up. Touch the L
    pin of the 2x3 connector to the gnd pin and the LED should light up again.

2. Insert a female connector with wires into the white socket. Connect a LED and
    series resistor between the two wires. Make sure the LED has its cathode
    towards ground. Short the Sd and R connection points in the 2x3 connector.
    Now the LED should be on whenever the sensor is not detecting motion.

3. If you have a oscilloscope, you can connect a probe to Sa or Sd and watch
    the sensor react to motion. Sa will drift to ~Vcc/2 if there is no motion for  a
    period of time. Motion will drive it off that bias point either in the positive or
    negative direction depending on which way the PIR is upset.

If you pass these 3 tests you are good to go. This project turned out to be a lot of fun.

Do not forget to keep the Fresnel lens to cover the sensor, it improves the sensor's sight. Position the lens over the sensor. You will find that it fits one way very well. To keep it in place, hot glue the tab that sticks over the PCB to the board. You might want to trim the long part that fits over the top of the board.


khammond4 (author)2013-05-16

Any chance theres a part number on the solenoid valve? I need a way to control the flow of butane electronically and the part needs to be as small as possible, and I also need several of them, but I don't want to have to purchase several air fresheners for the part... Thanks for this though! I'll probably buy one to prototype. :)

Smitho (author)2013-03-17

HI, this hack is great. Thanks. I want to add upstaris-light to sd, how can i do this? i haven't idea. Thanks

Doug Paradis (author)Smitho2013-03-18

You have to be real careful when building a circuit that will be interfacing with a home's mains power.

You could use this module with a triac (with opto-isolation) or a relay to power a lamp. However, I believe that hacking an outside security lamp with a motion detector would be easier and safer.

These types of lights use the same type of PIR sensor.

You might be interested in

Johnh368 (author)2013-02-17

I would like to attach a simple 4.5v load this project. I don't have any training in electronics but am capable of performing the approaches above. Which is the appropriate approach and how do I connect the load in the end? Thanks in advance for any advice.

Doug Paradis (author)Johnh3682013-02-18

If you have kept the full circuit board and modified it as shown in step 9, you should be able to connect your load as described in test 2 on step 10 (testing the white socket).

You should keep your load's current requirements at 200 mA or less. If you need more current than that you might try a small relay.

Please note that this module doesn't latch, so your load will switch as people come and go.

3gen (author)2012-08-01

Can i use this to light up some leds i want it to turn on when i drive up to driveway where there is no 120volt power available

Doug Paradis (author)3gen2012-08-02

This hack could be used as the sensor for the system that you describe. However, I would suggest that you look at Harbor Freight's 36 LED solar security light (item: 98085). This item is ~$20 when you use a 20% coupon and seems to be a good fit for your purpose.

It uses a similar PIR sensor to detect movement.

3gen (author)Doug Paradis2012-08-03

Thanks for your help that is just what i needed

cmacdonald3 (author)2012-06-19

Great instructable!
I want to add a motion sensor to an artwork to simply switch on a large LED powered at 5v, when there's motion this seems like a easy access and low cost solution.

legoman44 (author)2011-06-15


Not exactly sure why you drilled holes through the PCB for the jumpers. Could you not jumper the points from the other side of the board and not drill?

R.A.T.M (author)legoman442011-06-16

ya i dont see the point to drill other than neat ness

DIY-Guy (author)R.A.T.M2011-11-21

I like neatness, but my worktable is a pile of projects without visible order to the untrained eye.

Doug Paradis (author)legoman442011-07-04

     There is no requirement to drill the holes, however I believe there are a few benefits.

      Usually when first trying to understand the circuit, I drill locations that appear to be manufacturing test points or where blocks of circuitry seem to end. I then solder a small piece of wire into each hole and use them as test points while determining what the circuit is doing. The wires make it easy to make measurements with either meters or oscilloscope. I also found that when I drill the holes, I reduce my chance of disturbing surrounding surface mounted devices or lifting a solder lead. I'm not the most skilled person with a solder gun. As R.A.T.M mentioned I also find it a little neater and stronger.

Robot Lover (author)2011-10-16

Great hack! I personally would have just soldered the coil in a relay to the leads that would go to the motor. That way whenever someone walks by, it energizes the coil in the relay instead of the motor.

skylen (author)2010-09-25

I have to ask, Air Wick: What is the point of the "security screw" in this instance? I understand the use in public places to help impede theft/vandalism, but for an air freshner... really? Anyone who actually would be interested in re-purposing (hacking) the internals would laugh in the face of this silly fastener as an impedance to entry.

iectyx3c (author)skylen2010-09-30

Good question. I thought about why they would put these TP3 tamper-proof screws throughout the gadget.

@ First idea was to prevent kids (ages 8-108) from tampering with it.

@ Then it might be to keep smarty-pants from repairing it so ya have to buy a new one.

@ But finally the true (!) reason hit me: it's a failed preemptive strike against I'ble makers from buying the unit for parts!

RichardBronosky (author)iectyx3c2010-11-26

#3 is TOTALLY TRUE. They often sell these kinds of things for a loss so that you will by the refills and they can make the real money. It's the same thing they do with razors and printers.

#2 is definitely not it. They don't want you to buy replacements units that they make no money on. They want you buying the refills that are very profitable.

thines2 (author)RichardBronosky2011-06-17

Often the security type screws are used in robotic assembly type constuction, because the heads tend not to strip out, and the bits tend to last longer because of the larger surface area in contact with the fastener.

Doug Paradis (author)thines22011-07-04

Good point.


DIY-Guy (author)Doug Paradis2011-10-09

I noticed after using square drive screws (for decking) that the star or "Torx" tip pattern almost never strips out. How do the triangle head screws compare to others? Can someone comment on the quality of the triangle head screws please?

lferrier (author)2011-10-09

This is a very useful hack as PIRs can be used for lots of things. I found it incredibly easy to do and use. Thanks so much.

ross_valusoft (author)2011-10-09

I took the simple approach; just connected the led of a cheap optocoupler (CNY 17-3) in parallel with the Wick unit's green LED. Ten minutes and done ...


Ross McKenzie
Melbourne Australia

asorton (author)2011-07-24

I want to hack the unit so it works with the PIR but does not spray eery half hour when nobody is about, can this be done?

Doug Paradis (author)asorton2011-07-24

If you cut the trace near node "R" in the picture on step 6 and step 7, you disconnect the controller under the epoxy from the preamp of the power transistor that drives the spray solenoid.

If you jumper between nodes "Sd" and "R", the air freshener should spray every time the PIR is tripped. This could be a lot of spraying in a short time. You most likely would prefer to have a delay after spraying before spraying again.

One thought would be to rig up a 555 timer circuit on a small piece of perfboard, with node "Sd" as the input and node "R" as the output.

Please note that I haven't actually tried this particular modification. You should also read the comments below discussing adding a small reed relay.

R.A.T.M (author)2011-06-15

could you hook the black one to a mortor and whit to power sours and can you chang the timming so it go off evrtime that it senses moten

PatYoungers (author)2011-03-15

I put this small circuit to use as an IR activated nightlight.

legoman44 (author)PatYoungers2011-06-08

Regarding your circuit, can you be more specific on the mosfets you used (depletion zone/enhancment zone). Why are you using a pfet and nfet? could you not use two nfets?

PatYoungers (author)legoman442011-06-09

The P-channel is a Vishay Si4413ADY power FET enhancement mode device.
The N-channel is a Supertex TD9944 dual FET enhancement mode device.
This circuit does not require special FETs to work, just some that are good enough since this is not a power amp or a radio. I had "easy access" to these so I used them.
Both are surface mount packages and require good eyes or a microscope to handle. At 50+ yrs old, I had to use a microscope. I'll use vacuum tubes next time.
Have a look at the schematic at the link in my original post above to go with this explanation.
An N-Channel FET would not work for the first stage when driven by the SD signal because the logic is inverted. That is, the SD signal is at 4.5v when not activated. So you need a transistor that will be off when the gate and source are at 4.5v. So I used a P-channel FET. When iMotion circuit is activated, the SD signal drops to about zero volts, turning on the P-Channel FET. That charges the capacitor up to 4.5v, which in then turns on the N-channel FET, lighting up the LEDs. When the iMotion stops sensing the IR disturbances, the SD signal returns to 4.5v and the N-Channel FET turns off. This allows the 100K resistor to slowly discharge the capacitor which slowly turns off the N-channel FET reducing the current through the LEDs and making them slowly fade out. When the voltage on the capacitor reaches something less than 0.5 volts, the N-channel FET and the LEDs are basically off.
That's a bit more than what you asked, but I was on a roll so I kept typing. I really need to turn this into an instructable.

hoonflap (author)2011-05-26

just to verify, the digital signal available after completing step 3 is a solid 5v, correct? or 4.5ish, i see 3 AA's? i want to trigger a 5v reed relay. would i need any additional steps?

Doug Paradis (author)hoonflap2011-06-01

       I believe that your question has 4 parts:

O1:  Can the Vcc for the module be 5V?
 A1:  Yes, I have used the module in circuits from 3V to 6V. I do not know
         the BVCDO of the transistors or the BV rating of the capacitors
         in the module, but they are greater than 6V.

Q2:  Can I drive a 5V reed relay directly from the Sd node on the
   I am going to make 2 assumptions here;
                1. You are using a reed relay similar to Radio Shack part
                     275-232 (i.e., 5V, 250 ohm coil). So you are asking
                     can the Sd node source 20 mA.
                2.  Since the Sd node goes low when the PIR is upset,
                     the coil would be energized most of the time.
        The Sd node is the collector of transistor Q4, which is connected
        to Vcc through resistor R14. R14 is ~100 ohms. At 20 mA, the
       voltage at Sd would be 3V (i.e., Vsd = 5V - (100 ohms * 20 mA)).
       I do not know if this is enough to energize the relay's coil. I would 
       have to try it to find out. If you use the diode protection I mention
       below,  I do not think that you will damage the module.

Q3:  Would I need to do anything else to the circuit?
A3:   You need to put a reverse diode across the relay coil to
         handle the inductive kick when the relay switches.

Q4:  What if that doesn't work?
  I would go through the Instructible a little farther and make the 
        power transistor and its pre-amp accessible (node R). It was
        designed for this type of purpose and has the necessary diode
        in place.  It would also have the additional advantage of inverting 
        the signal so that the relay coil would not be energized except
        when the PIR sensor was upset. 


BVCEO not BVCDO..... dang typos

    I just rethought my answer a bit. If you...

1. Connect one end of the relay coil to Vcc and the other end to the SD 

2. Put in the reverse biased diode to handle the inductive kick across
     the coil.

3.  Disconnect or remove R14.

Q4 should be able to handle a small reed relay directly. It would also
only be activated when a disturbance occurred.

Hope this helps.

One last thing, just to make sure you are aware...

     The PIR will give multiple trips as someone moves or walks across its path. It will detect movement or sudden changes in IR radiation (i.e., an object in shade suddenly becomes an object in direct sun light or a warm object, say leaves on a  tree in sunlight, start to wave with the wind).

    The Sd node doesn't latch or lock itself out for a delay. It wil report the continous status of the PIR sensor. When the sensor is unbalanced, the node will go from Vcc to ~gnd. See the last photo
on step 3.

You might be interested in for some ideas how to handle these issues. 

Annoymous (author)2011-01-31

They Suck i know people that have them. Not this type but they have the Freshmatic and Straight Freshmatic Mini and they get sprayed in the face all day.

kelceysyoung (author)2010-11-04

What is the point of this? I mean it looks really neat but i'm not sure if i understand the point.

sillywilly (author)kelceysyoung2011-01-30

Sorry someone didn't respond to your question sooner kelceysyoung! You can use this modified/repurposed PIR to trigger several projects but the best one is one member KipKay did with another PIR and a miniture DVR camera to take pictures when warm body moves into view i.e. as a game camera, snoop on a unknown nanny, (or any other person who deserves it), use it to catch that bad neighbor in the act, or perhaps to find out info on who has been breaking in?

Callum Snowden (author)2010-09-30

You can just use a small flat-headed screwdriver (the ones that look like this "--" on the end") and just wedge it in between the two points of the triangle on the screw :)

I've found that the tip of one side of a pair of needle nose pliers sometimes works as well

I suppose it would work quite well if the head is quite large

Computothought (author)2010-10-29

Hmm mine looked complete different inside, but it did have the pir. Mine was wall powered and had two boards. The board with the pir had 3 wires coming off of it. the power supply was in the other board. There was no motor inside also. Maybe I can get a schematic from the fcc if I can numbers off the board. I am amateur at this.

If it is wall powered, you picked up theAir Wick i-Motion Scented oil warmer instead of the Air Wick Freshmatic Compact i-Motion air freshener. It is a different product. I chose the air freshener, because I thought that it might have more usable parts.

I would be interested in what you found inside of the oil warmer. Would you post some pictures of the insides? Does the power supply look like it might be something that could be used on other projects?  

I could not find the one you had. It said imotion on the box. There was a different one a another store but it was near $20 dollars. I passed on it.

The correct product is labeled "AIR WICK FRESHMATIC COMPACT i motion Air Freshener". It is readily available at Walmart, Target, and Walgreens for about $8. Walgreens has run a half price special several times in the recent past. I'm not sure what product you saw for 20 bucks, but that isnotthe right one or very over priced.

I have inserted apicture of the packaging into step 1 of the instructable. I hope that helps.

From your picture it looks like the oil heater version has a nice power supply. I will have to take a look the next time they go on sale.

I think I finally found the right one at Target. That product was not at Walmart or Walgreens when I first looked. I went over to Walmart for something else and saw they finally had it back in stock. Target was a dollar cheaper than Walmart. Thank you for your patience.

snander (author)2010-09-24

Woohoo! On sale right now for $3.99 each at Walgreens.

Sovereignty (author)snander2010-09-30

My wife comes home with the electric air-fresheners [all brands] for under a dollar each, sometimes free; sometimes the stores are paying her to leave with them. She's also been treating me to bottles and bottles of Scrubbing Bubbles with the auto-triggers, and a few other products [same manufacturer] that have the same 1.5v pumps; for pocket change! The battery included is worth more alone than what she ends up paying. Oh! And more recently, the bug repellent clip-ons. I've thought of a few clever uses for those, but this stuff is coming to me at exponential rates! I almost forgot to mention the free battery powered razors...with the cute little clippers on the end... ... ...and it's waterproof! Oh dear!

Them crazy couponing folk are real; and they ain't all that crazy. I'm married to one. Like the l337 to the n00bz, she scoffs when people mention their 25, 30, 50 percent savings. She's to the point where she spends very little time doing the prep-work. She has fun doing it, anyway-- 'cept when Walgreens gives her a hard time. She loathes Walgreens. Well, I'm sure there're more than one coupon -ibles out there.

Oh, thanks for the -ible, Doug.

tbcross (author)Sovereignty2010-09-30

you know I am a deal hound myself, I feed 3 very very tall teenagers and myself and all the scraps the dogs and cats munch on every month for less than $400, but oddly enough though I never use coupons! I would like to, but it just seems like too much. Maybe you could get your wife to part with her coupon-ing secrets for an ible??

Sovereignty (author)tbcross2010-10-01

No secret in it, really; she went to the Southern Savers website ['cause we're in Tampa] they had tutorials that she read through, and after a while she learned those basics by heart. She checks the fliers, collects the coupons, save the store 'rewards', etc. The only difference you'll have is by region [and I'm sure there're coupon sites dedicated to most popular regions in the US...or abroad] The entire process would be tedious but the lady on that website mentioned does alot of the footwork for you, finding the deals and such, so it'll only benefit those of us in the south-east region.

And of course, depending on an 'INDIVIDUAL' store policy [yeah, right], you may or may not have MMA matches with store managers, fist-a-cuffs with crotchitty old bats, or be incarcerated for putting your fist down an obnoxious teenie boppers throat. Prepare to be treated like a criminal when you leave some of these stores; but then you'll know you're doing it properly [and legally]. Here's a hint though, my wife always says she'll choose a teen boy cashier when in doubt. To quote her, "...they just don't give a crap..."

tbcross (author)Sovereignty2010-10-07

haha I have actually noticed the teen boy phenomenon after a Thanksgiving turkey markdown at wally world, the elderly lady that checked me out turned something that should have been a few seconds in duration, into an investigation that took half an hour despite the clear print on the flyer! I swore off any line at the Mega store that wasn't headed by someone who routinely used OMG and BFF in conversation!!

MRedmon (author)snander2010-09-26

I saw your comment around 10p on 9/25... just 3 hours before the sale you mention ended. I knew I wasn't going to be going by any Walgreens before midnight. Luckily, I happened to see the i-motion on sale at Walmart for $6. With 23 minutes to spare before midnight, I convinced them to pricematch Walgreens sale and got two units for $4 each. Thanks for the heads up!

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