How to Install a "garage Door Open" Indicator




Introduction: How to Install a "garage Door Open" Indicator

About: Experienced marketer with over 30 years in consumer durables and industrial products marketing. Writer, blogger, patent holder, avid golfer, committed DIY-er. Check my blog for more DIY projects.

Ever left your garage door open overnight? In addition to being a terrible energy waster, all the tools, bikes, and other stuff are available to thieves - who might even enter your home via the door from your garage to your living quarters.

Install a simple indicator which will alert you if you've left the garage door open. Total cost is less than $30-$40, and you can determine exactly where the indicator will be located.

What you'll need:

-A 24 volt doorbell transformer
-1 push button "normally open/momentarily closed" switch
-1 red LED - 2.8 volts
-1 4.7k-Ohm resistor (specific part numbers for the electrical components are provided in Step 2)
-2 strand bell wire
-Electrical tape and/or heat shrink tubing

-Wire strippers
-Soldering iron + solder
-Electric drill
-Misc. hand tools - wrenches, etc. - depending upon the specifics of your installation

Let's get started...

Step 1: Identify a Switch Location

Your first step will be to determine where you can put a switch to close the indicator LED circuit.

When I looked at my garage door, I noticed that a piece of galvanized trim on the top of the door stopped right next to the angle iron used to hang the door tracks when the door was in the fully opened position.

I bought a simple corner or "L" bracket and mounted it from the bolt that connected the wheel track of the door to the vertical angle iron bracket. A simple Radio Shack "normally open/momentary close" push button then mounted on the other side of the corner bracket, with the switch of course facing the top of the door.

By bending the bracket slightly, I was able to ensure that the switch was fully depressed every time the door was fully opened.

This arrangement might work for you, or you might have to improvise a bit. You of course want to mount the switch in a manner that it's in the "closed" position when the door is open.

NOTE: in the image below, I stopped the door's movement before it reached the fully open position so you could see the orientation of the switch in relation to the top of the door. When the door is fully open, the red push button is fully depressed, and the circuit is closed. (See 2nd picture below.)

Step 2: Wiring Diagram

Before we go any further, a simple wiring diagram.

The system uses a 24 volt doorbell transformer as the power source; a 4.7k-Ohm resistor knocks the voltage down to that required by the LED (~2.8 volts.)

All of the electrical components are available at Radio Shack and will cost approximately $6.

In addition, you'll need some 2 strand bell wire; how much depends upon where you plan to put the LED. More on this later.

All of the Rat Shack part numbers are indicated in the diagram.

Let's take a look at how I mounted the doorbell transformer in the next step...

Step 3: Wiring the Transformer

I used a variable voltage (8-16-24 volt) doorbell transformer made by Heath/Zenith. It cost about $15 at my local home center. You need a transformer that produces 24 volts.

I direct wired the transformer to a grounded, 3 prong plug and mounted it directly above a power strip near my workbench. The 4.7k-Ohm resistor was soldered in place and then secured with a piece of heat shrink tubing I had on hand; it's directly beneath the transformer in this picture.

If you wish, you could cover the wiring with plastic channel for a neater appearance; I simply chose to use insulated staples.

One other thing I did later on was to plug the power strip into a lamp timer, and set the timer so the strip is on only between 8pm and midnight. There's no reason to power the transformer 24/7, as the only critical time is at night when we're going to bed and (presumably) have forgotten to close the garage door. Which leads us to the final step...

Step 4: Install the Red LED Indicator

After thinking about this for a bit, I figured that the absolute best location for the "door open" indicator was in the master bedroom.

It could have gone in the kitchen, or mud room (whose door connects to the garage) but my logic was "if I could remember to look at an indicator in one of those rooms, I could just as easily remember to open the mud room door and check the garage door."

To be absolutely foolproof, I thought it had to be in the master bedroom. Looking around the room, I thought of getting at the ceiling light fixture via the attic, and perhaps placing the LED inside the light's frosted globe.

In the end, I decided to drill a small hole in the decorative trim on the light, oriented so it faces the head of our bed. That way, if the LED was illuminated, you couldn't help but notice it when you went to bed.

I was able to route the wire from the garage all the way through the attic to the location of the master's ceiling light. (NOTE: this was the most time consuming step in this project.) Working from the bedroom, I drilled a small hole next to the light's electrical box, within the diameter of the light itself. I then fished the wire through from the attic, and made the connections to the LED. (As with the resistor, the wires were soldered to the LED's leads, and everything secured with heat shrink tubing. You could use electrical tape for this; just make certain everything is sealed really well.)

And that's it. As mentioned earlier, I put the system on a lamp timer so it's operational only in the evening.

It works perfectly, and we're now assured that if we forget to close the garage door before retiring, the LED will bring us back to our senses.

Total cost of this project was around $40, and that included 120 feet of bell wire. YMMV; bell wire costs about $ .20 per foot.

If you've read this far and enjoyed this project, please consider visiting my blog - Practical Hacks - at

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    Tip 1 year ago on Step 4

    Very nice, but If I may be so bold: :D
    The opener already has 2 reed status switches - one to tell the microprocessor the door is up, and one for down. They run on 5 volts. Use one (or both) as the signal AND the power source!! See my Instructable on how. Note - you will need an 800 ohm resistor on the LED as to not load down the signal to the microprocessor.

    You had me going with your description of the hassle of running a wire to the Bedroom light - I could'a sworn you were going to say you ran a wire to an easy location and connected to a laser pointer, which you then pointed at the ceiling light (or anything else you wanted to!!)


    4 years ago on Introduction

    I enjoyed reviewing your garage door open/close sensor design. Thanks for the input. Where in your schematic is the sensor wiring indicated? Did I miss something?

    Thank you. Doug


    5 years ago

    Is the white bell wire connected to the transformer? So, it seems like I
    need to run the bell wires from the push button switch, with the white
    going directly to the LED and red heading INTO the transformer and then
    another red segment heading OUT OF the transformer, with the resistor
    soldered in-line, and going to the other connector on the LED. Is this
    correct? Additionally, if I were to modify this design for a 2-door application, I would need a separate resistor for the 2nd door correct? Or not?


    6 years ago

    The mission objective and notification LED is brilliant! As I understand it the way the switch is mounted: it senses that door is either fully-open or not fully-open. I would be interested in photos of sensors that confirm that the door is fully-closed or not fully-closed. The distinction is that in the photographed configuration, there is the possibility that the door is partially open, which would not trip the switch (LED notification). Again, this would be perfect reminder for renters that leave the door open.


    8 years ago on Introduction

    I need something like this (or this exactly, in fact) because I have backed into my garage door too often, in too big a hurry to back out. This last time I backed out so quickly that we had to replace the door. I am going to install this to fully indicate that the door has opened, so it is clear for me to back out (No comments about women drivers, please!).

    I have a commercial position indicator, but that won't quite work. The sensor detects whether it is vertical (door supposedly closed) or horizontal (mostly open). It does not indicate whether it is 100% fully open or closed.

    So I will install this and put the LED (green for my installation) in my line of sight right there in the garage. Maybe I'll even get creative and make a sign that lights up that says "OK" or something.


    Reply 7 years ago on Introduction

    Never backed into my garage door like this. Just wait for the door to open, then back out, not hard to do. Really, wth? Backing into your garage door is a normal occurrence? lol


    Reply 7 years ago on Introduction

    I have three dogs that get rather chaotic when it's time to go for a "R-I-D-E." And one dog needs help getting in the car. Usually I open the door when we go into the garage, but if they are super chaotic for some reason, it has happened a couple of times that I think I opened it, but didn't. Our biggest is a Great Pyrenees, and if he gets in the way of the rear view mirror, I can't see a thing out the back.

    Sh*t happens, what can I say?

    I would think a better way to do this is to use a normally closed switch and mount it so it is pressed when the door is in a fully closed position. That way if the garage door is partially open the switch would be pressed.


    7 years ago on Introduction

    Thanks Journeymanjoe for pointing out code violations. You are right the average DIY homeowner might not know these things. (Unless that person is also a Electrician) None of us would like a house fire...that would be way more costly then hiring a qualified repair person. I did find a helpful site if you all want to fix some other things...some of our rollers got unscrewed and fell the whole attachment came off.


    Step #3 is a National Electrical Code violation and a hazard to anyone that comes near it! You can't have exposed energized parts over 50V (should be installed mounted to a box with the 120V wires inside the box), that is why they make these transformers (primary side is 120V and the secondary is 24V). It is a violation to use single conductors with this plug (the plug is made for use with a cable).

    Step #4 is a National Electrical Code violation also, you can't modify a listed luminaire (drilling the hole in it); you can't mix the low voltage with the 120V power in the luminaire.

    This is why homeowners shouldn't be doing electrical work, too often we hear about residential fires blamed on bad electrical wiring (would be nice to know how many were wired by the homeowner)! Please hire a professional, licensed electrician to do any wiring. The money you save by doing it yourself is not worth the risk to your life and property.


    9 years ago on Step 4

    I have built a very similar setup for the same reason. I've used the doorbell itself as a "base station"; the LED is mounted inside the doorbell housing which is located in the main living area in a prominent position. The doorbell runs on four "D" cells, and I siphon off 3V from two of the batteries to power the indicator.
    I notice you say "You need a transformer that produces 24 volts." Is this to overcome the resistance in the wire over the long distance to the garage door? I found the 3V from the batteries works fine on mine, and the wire goes for about 20m (60ft). I think there is a loss over that distance but the LED draws so little current that it doesn't matter.
    Great instructable, kjc2010. We're obviously thinking along the same lines!


    9 years ago on Step 3

    You state that there is no reason to power the transformer 24/7 and I agree.

    Couldn't you wire this thing to power the transformer only when the door is open? The simplest way might require passing 120v thru your switch.

    Great project and well documented. I had a similar thoughts around this very same project idea. However I do have some concerns that may have already been stated or otherwise addressed within the threads of this conversation:
    • This project appears to address a garage door being in the "fully open" position rather than indicating that the door is "closed" (completely shut and secure).
    • The use of a push-button switch would lend itself over a period of time to be pushed out of range should the door or the switch be moved or otherwise become misaligned.
    • Use of a "leather finger" (mentioned earlier in the thread) might address the above alignment issue, however it might be subject to temperature or other physical factors requiring additional maintenance.
    • This solution might not address multiple garage doors that are more common place in today's homes. Likely this requires a slight modification to the project to address this situation.
    • This solution requires running wire back to the interior of the house (e.g. master bedroom)
    Having just begun tinkering with Arduino platform, I might suggest an alternative approach that might address these issues:
    • Single Arduino microprocessor plugged into garage wall-outlet and mounted near garage doors
    • Each garage door to be outfitted with window security-type magnets near top of interior door frame
    • Install sensor (Hall-Effect or Reed) aligned to magnets when door is in a fully-closed position
    • Each sensor is hard-wired to (separate pins of) the Arduino microprocessor
    • Appropriate Arduino code/logic is uploaded to monitor state of each sensor
    Once the Arduino remote monitoring device is installed, additional Arduino communication "shields" (extensions) could be installed to advise the homeowner on the current/changed state of each individual garage doors.

    My current thoughts include the following scenarios to exploit the logic programming and features of Arduino:
    • Wireless Ethernet to send email or SMS when a door is opened/closed during unscheduled period (e.g. work hours)
    • Update a website status when door is opened/closed (e.g. Ethernet wirshield)
    • Allow your cell to communicate back to Arduino for further action (e.g. close door)
    • Sound chime in house when doors are open longer than X minutes (use Arduino logic)
    • Sound alarm in house when doors are opened anytime from 12AM to 7AM (use Arduino logic)
    • Implement X-10 interface to light up a lamp or chime an alarm (alternative to tie into X10 automation)
    • Install RFID sensor on exterior of garage wall to allow for kids to use RFID style key-fob to enter house via garage.
    • Maintain a log of all openings/closings over period of time (e.g. write to internal or external log file)
    While not all of the above scenarios will be adopted by the reader, it just shows that you are only limited by your imaginations. I hope to begin work on this project and will promise to share/post my results in this forum.


    Reply 10 years ago on Introduction

    Great minds think alike as they say.I juat came across this post as I was curious if anyone else implemented what I put together. I built exactly what this person had suggested. I have a WiFi Arduino board connected to my 3 garage doors. I installed a door alarm magnetic reed switch on each door to determine its open/closed state. If any door is open for more than 5 minutes, a Tweet is sent to my wife's cell phone and an Email is sent to my Blackberry to tell us the state of all 3 garage doors. Only when all 3 doors are closed again do we get another message to tell us everything is back to normal.

    My wife is always concerned that she may have left the garage door open when she leaves and now she only needs to look at her mobile phone.


    Reply 9 years ago on Introduction

    instructable? I'm very interested in doing this, so please create one!


    10 years ago on Introduction

    Most garage doors already have a light on them indicating that it's open. Wouldn't it be much simpler to connect a socket receptacle to the existing light and just run the power to any light in the house? You may be over-thinking this one.


    11 years ago on Introduction

    It's been said already, but you could run 4 conductor wire (telephone or CAT3) and have the other 2 wires hooked up to the switch for the opener. Then you could close it from within your bedroom. I'd probably recommend a reed switch (switch activated by a magnet) inside that same light fixture, and then you could just wave a magnet by it. Wait 20 seconds, and when the light goes out, the door is closed. Either way, very nice project. Definitely going on my to do list.


    11 years ago on Introduction

    Nice idea, i believe with the proper calculations/components you can use 120vac, no need for a transformer. LEDs only drop 0.7v, so find the appropriate resistor value to limit the current. CAUTION: when working with 120VAC a certified electrician is required.