Introduction: A Wireless Version of ... Is My Garage Door Open or Closed?
We wanted a simple, cheap and reliable indication system which showed us if our garage doors were open or closed.
There are plenty of "Is my garage door open" projects. The largest majority of these projects are hard wired. In my case running wires between the sensors and the receivers was not possible. It's only 25 metres about 80 feet, between the garage and the house but we don't fancy digging up concrete to place wires and anyway, we expect others who share a common space with us would like it even less.
Our problem is we don't have a line of sight from the house to the garage door. The garage is a separate building.
Sometimes we have left either or even both doors open over night and as we don't want tools to go missing from the workshop or have our car disappear so we thought something which shows the door status is a good idea.
We already have a wireless remote control opening and closing system installed. It is a rolling code system and the 433 Mhz signal is very difficult to duplicate so that part of the system is safe and reliable. The problem is when we use this system from inside the house we never know if a door is open or closed. We have actually pressed the garage button on the remote and locked up the house thinking the garage door was OPEN when in fact we had closed it. That is annoying especially if it is raining.
I can't stress this enough...
If you are going to build this project there is a warning. Closing garage doors without being able to see what is happening can be costly even dangerous to others who may be unaware that a door is closing. You might want to add lock out sensors just in case the car or something or someone else gets in the way of the closing door. Many garage door varieties have safety reverse mechanisms built in but...most only reverse after a substantial force is exerted on something that has been left in the way and we suspect your car may look better without a long dent across the body or worse an emergency trip to a hospital.
Skills needed to build this project
Mechanically minded and basic electrical or electronic skills
Ability to solder reasonably well
Ability to look at a circuit board and identify switches and connection terminals
Ability to do basic work with sheet steel or tin plate such as cutting and bending
Tin plate cutters
Small screw drivers
A medium hand file or sand paper (to remove sharp edges)
Soldering iron and solder
A bench vice (to bend tin plate)
Raw Materials (depends on positioning of sensors, transmitters and receivers)
Good quality double sided tape a few metres
Sheet steel or tin plate roughly 150mm x 100mm or 6 in x 4 in
Small cable ties at least 20
About 6 metres or 20 ft of figure 8 cable or speaker wire
About 6 metres or 20 ft of Cat 5 cable or something similar
Parts needed for the build
Remote and Receiver. Search Ebay for 12VDC 433MHz, 2 Button Wireless RF Relay Remote Control Switch Receiver Transmitter Kit. Match the one in the photo.
An illuminated Momentary 16mm Push Button Dash 12V. Search Ebay or substitute to whatever meets your needs
2 Micro switches
a LED light
A 560 Ohm resistor
2 x 12 DC volt power supplies - current max 200mA only 1 needed if you use the transmitter batteries
You may also need a mounting box or other method to make the indicator buttons look good
The cost to build this is about $A25 but we did have both 12VDC plug packs in our junk box, as well as wire and other common bits lying around. We built 2 units and integrated this into our wireless remote door opening system installed about 12 months before
Step 1: About This Project
My garage doors are roller doors or in some counties they are called roll up doors. They are called roll up doors because this is exactly what they do. They have a guide track attached to the wall on both sides of the opening. As the door moves down the roll unwinds into the vertical guide. The door is constructed of ribbed sheet steel or often aluminium. We will be using the vertical guide and the base of the door on one side to position the sensors. This project will work with just about any variety of door. It is more about finding a suitable switching mechanism and a place to mount the sensors.
We have 2 doors that require a monitoring system. We will build two units, one of these for each door. For no particular reason we chose a Frequency of 433 MHz. We chose to build the product from easily purchased complete working units on eBay as we don't see the point spending the time building something when the time and cost will greatly exceed a simple PayPal spend of a few dollars for each door. Maybe we are just lazy. To keep this project simple we will only consider 1 door. The second door is simply a repeat of the project using an additional separate transmitter and receiver.
Step 2: Security
As this system is only a status reporting circuit, we used a learning remote system. Yes, we know these are easy to copy or duplicate but in this case there is little value in building this system using high security rolling code device if the system we are building can't open or close the doors.
If someone with far too much time on their hands wants to copy the transmitter signal they will soon find that the door will not open and whilst a copied signal may give me a false positive on the status of the door if it is hacked over a single opening or closing cycle the sequence will self correct.
Step 3: Schematics
There is 1 remote, which we will call the transmitter from this point forward, and 1 receiver. The transmitter is installed in the garage. It is powered by 1 x 12 Volt battery a 27A. A battery comes with the transmitter and replacement batteries are easy to buy. It is quite OK to use a battery to operate the transmitter as there is no standby power drain. The battery is only connected when one of the buttons on the remote are pressed most of the time the transmitter it is OFF. For this project we will be connecting the battery terminals to a 12 Volt DC supply so we don't need to worry about replacing batteries in the future.
The receiver is installed inside the home. It is also connected to a 12 Volt DC supply. The receiver has a small power drain when it is busy receiving signals. This is only a short time period about 1 second then the receiver reverts to standby which uses 30mA. If the door is open the standby 30mA in creases to 50 mA as a relay is held closed and a LED light remains ON.
The receiver will be hidden somewhere out of sight connected to a control panel near the front door. We will fit a button to open the door which will have an inbuilt light, like the completed in house indicator and switch plate system above. For our project there will be a button to open each door and a light that remains ON if that door is open.
The Ebay transmitter and receiver
The transmitter came matched with the receiver so we did not have to program the transmitter to match the receiver. If the transmitter needs to be matched to the receiver it is a simple matter to power up both bits and press the program key on the receiver circuit board, the power LED will go off. Next press any button on the transmitter. The receiver power LED will flash a few times. Then press any key on the transmitter and its done.
The only other connection is to connect a LED between the normally open contacts of relay on the receiver circuit board in series we used a 560 Ohm resister. If the ON button is pressed the transmitter will light up the LED on the receiver. If we press the OFF button the light goes out. An important feature of this system is it only changes state if the other button is pressed. In other words if we press the ON switch of the transmitter the receiver LED switches ON. if we press the ON button again the LED light remains ON any further ON signals are ignored by the receiver. It is the same with the OFF button. If the transmitter sends an OFF signal the LED will go out on the receiver. Any further OFF signals will be ignored. This change of state sequence will ensure the opening and closing signals do not get cross up and provided the sensors are working properly the system is self correcting if it does get out of sequence.
Step 4: Modifying and Building
The first step is to modify the transmitter. This is removed from the 2 button remote enclosure. Next we locate push button switches on the transmitters and solder a good length of figure 8 cable across the both sides of open side each switch. Now we have 2 x figure 8 cable connected to the remote switches. Next we connect each wire to a micro switch. At this point all we have done is made it possible to operate the switches on the transmitter by activating the micro switches.
Positioning the sensor switched
Every door will be a bit different but choosing a place to mount the micro switches on the garage door guide is an important step. This is best done near ground level. The OFF micro switch is attached to the garage door track roughly 40 mm or about 1 and 1/2 inches from the floor, just above this sensor we position the ON or the OPEN micro switch. To finalise the sensors we attach an aluminium leg to the bottom of the garage door and bend this at 90 degrees so we can add a short piece to the vertical part of the leg filed with a nice lead in so it gently activates the micro switches as the leg moves past the switch assembly. See the video.
Proof of Concept and Testing
The Up and the Down videos shows an initial mock up of the concept. (We really did install it properly later) In both videos you will see the Switch Activation Plate slide past the switches and depress each one. What is harder to see is the indicator light on the transmitter which is precariously mounted on a roll of duct tape. Each time a switch is activated this indicator light is switched on momentarily indicating a signal is sent to the receiver. The receiver is carelessly resting on the floor supported also by a roll of duct tape.
Now let us see what happens when you close the door. As the door closes the Switch Activation Plate passes the ON or OPEN sensor first. This will momentarily activate the LED on the receiver signalling the door is OPEN but this immediately changes state as the door passes by the OFF or CLOSED micro switch before the door stops at the floor. The absence of any indicator light means the door is closed.
Now we open the door. When the door begins to open, the first sensor it passes is the OFF or door closed sensor. As the OFF micro switch was passed when the door last closed the receiver will not change state. Yes we agree the door is open about 40 mm and we are not going to worry about this, but as the door continues to go up just a little further the ON or OPEN micro switch is activated this sends the signal to the transmitter closing the contacts on the relay and switching on the LED indicating the door is OPEN.
Step 5: Mounting the Transmitter and Receiver
In our project we removed the 12 volt battery and connected a 12 volt supply directly to the battery terminals. We needed to find a dry place to mount the transmitter. In testing we found the transmitter worked even if it was placed near the aluminium garage door but experience tells us the position of the transmitter should be high above the garage door. We chose to put the transmitter into a simple plastic box and screwed it to a wall batten about 300mm or 12 inches above the garage door out of the way.
The receiver was taken inside the house and mounted inside the roof cavity near a gable that faces the garage. We put the receiver it in a small plastic box and ran a 12 volt DC supply to the power terminals. Lastly we used figure 8 cable from the relay contacts and ran this down the wall cavity to an existing modified light switch plate.
The mounted receivers shown. There are two receivers. The other module is the previously installed garage door opener. This was modified some time ago. Basically the same attach wires to exiting switches and run the wires down the wall to a button.
The light switch plate is a larger type and only had one light switch so after we had carefully insulated all mains cabling behind the wall plate we modified the light switch plate to accept 2 momentary switch with a built in indicator light was connected to the receiver relay. See video.
The Micro Switches
Rather than mounting the micro switches to the door guides we bent a piece thin piece of steel sheet to match the profile of the garage door guides. This meant we were able to raise of lower the sensors to an optimum position before using double sided tape to finally place the sensor block in it's final position. We also bent another thin sheet of steel to cover and protect the micro switches from damage or being displaced. The connecting wires were cable tied and tucked out of the way. We used good quality double sided tap to mount the sensor block switches. We stress good quality tape is important as it will allow a certain amount of micro switch movement without falling off or coming apart yet this tape it is firm and reliable. The tape we used is automotive quality meaning it is resistant to water an temperature changes and it does stay stuck. It's been 3 months since this was installed with approximately 300 - 400 cycles during that time and the tape has not showed any signs of giving in.
Now we needed a way to open the doors from inside.
Up until now we have been using a rolling code remote to open the garage door. This has been reliable but it also brought the problem that we have set out to solve. We decided to continue using the rolling code remote to open and close the door but we integrated this into the new system. We modified this remote the same way as the transmitter for the project. The remote was opened and removed from the enclosure. We found the corresponding door open button on the circuit board and soldered a figure 8 cable across the open switch contacts. This cable was run down inside the wall cavity along with the indicator wire from the receiver and soldered to the open terminals of the momentary switch on the wall plate. Now if we press the momentary switch the rolling code system opens the door but the receiver from the project indicates that the door is open.
Step 6: Positioning Testing and Aerials?
So this is what it looks like.
See the video. We have a wall plate with a standard light switch and have added a new momentary push button switch which has a built in indicator led light. The momentary switch is separate to the led light so if we activate the momentary switch it does not activate the led indicator. When we push the momentary switch it sends a signal using the existing rolling code remote control which was installed a few years ago and it opens the garage door. We know it is opening the door as about 1 second after we push the momentary button the indicator light from our project turns ON confirming the door is open.
If we push the momentary button again the door will close however the light will remain ON until the door has almost fully closed. This takes about 8 seconds on my slowest door.
Testing, Results and some good thought
Positioning both the transmitter and the receiver is the key to reliability. We have a distance of 25 metres and a line of sight to the garage but can't see the garage door. We had no problem with reliability and there was no problem with changes in temperature however in Australia where we live a low temperature would be 6 - 8 degrees Celsius and high temperature can be 45 Celsius. So far the testing range has been between 12 and 34 Celsius we are unlikely to get any more cold days and it will be February before the hot days arrive. We also live in an area with no street wires no high tension wires and no public wireless WiFi or Internet. We also have a poor mobile (cell phone) signal strength and whilst we would not expect any of these things to impact on the 433 MHz signal the many and various signals in our airways can have very unpredictable effects and can cause properly constructed circuits to simply not work or fail to achieve a suitable signal strength reducing the communication distance.
Do we need additional aerials.
In testing we found the transmitter was able to send a message to the receiver every time a test was done. A little experience has shown us in hot or cold weather extremes there is a chance that the signal may not be received. If a signal is missed due to communication loss in this build it will self correct the next time the door goes up or down. If any signal fails to get through the worse thing that can happen is the led indicator may give switched values. i.e. indicate the doors is open when it is closed or visa versa.
To date this has not occurred but should we install Aerials as a pre-emptive strike? In this project both the transmitter and the receiver have terminals on the circuit board that can be harvested to attach Aerials and increase gain.
We can assure you one of the best ways to improve the reliability is by choosing the best position to place the transmitter and the receiver. Some examples keep them away from large metal surfaces, such as garage doors...or a least 2 metres or about 6 feet away. Also try not to install either the transmitter or receiver in a closely confined space such as a wall cavity and if possible position the transmitter and the sensor in a line of sight. They dont need to visually see each other just try to avoid obstacles such as buildings. At this point early in the project testing we have found no need for Aerials with this project.
Whilst Aerials can be both complex and simple we would recommend the simple and see if this helps before spending money. If we get enough comments we are willing to add aerials to this project which we claim can increase the range. There will be little to no cost to create these and anything you need is likely to be available from your wardrobe and your junk box.
Step 7: Things We Would Do Differently If We Did the Project Again.
A critical review
With each project you have to be self critical and look at what you could have done better. In our case we were happy with the result but all constructors should think how their designs could be improved.
One of the problems with roll up doors is the driving motor is only on one side of the door. This single side drive marginally pushes the base of the door on the non driving side harder into the guide but when the door is closing the drive causes the same base of the door to be pulled away for the guide. In my case on one door the guides needed to be tightened as in initial setups the door would make contact with the sensors on an opening cycle but on the closing cycle it would completely miss the sensors. The movement was only 3 mm or about 1/8th of an inch but this was enough to make the sensors unreliable. We corrected this by tightening the guides but this was not the end of the problem and over the next few weeks we randomly had a light "ON" when the door was closed.
You may remember in this project we focused on 1 installation but we stated that 2 units were being constructed. Whilst there is a slight differences between the garage doors both sensor and transmitter arrays used on each door are identical.
One door is about 10 years old the other is about 1 year old. The older door moves up and down much faster than the newer door. The older door has more end play which we have reduced to what is described as acceptable end play movement but this lateral end play has not been eliminated.
No issues have been noted in the newer door. It has performed flawlessly over the last 5 months but we did have a persistent problem in the older door. Inspection showed the sensors seemed to connect and actuate with the slider mechanism. I can hear both sensors click. If I manually activate the open and closed sensors they both work fine switching the indicator light "ON". and "OFF" as expected.
Could it be at times, the speed of the door is a little too quick to register the first sensor signal and then immediately change state to register the second one? I don't have a way to slow the door movement but I can increase the distance between the sensors which will allow more time between the "ON" and "OFF" signal and we can increase the length of the slider actuator which will hold the transmitter switch signals for a longer length of time.
We increased the distance between the sensors to 150mm from 100mm and we also increased the slider plate from 75mm to 100mm. That was 4 weeks ago. There has been roughly 75 cycles and the system has performed flawlessly.
What would we do differently
If we were doing this project again we would start by using a normally open inductive proximity sensor switches rather than micro switches.
Using proximity sensor switches gives a greater range of error or sideways movement as much as 10 mm and the sensor speed is at least 100 times faster. We think if we used proximity sensor switches in the first place we could have left the door guides a little more room for expansion and contraction of the 2.4 metre or the 8 foot wide door which may be kinder to the door and motor over a period of time. We think the speed of the door would also have less impact on the reliability.