The Best Magnetic Driveway Alarm With No False Alarms

If you are wondering what is the best magnetic driveway alarm for the money, let me offer my years of experience having installed and used all sorts of different wireless devices for my own home security.

I have installed what I believe is the best value magnetic driveway alarm.

Actually there are two. I have both systems installed. However this review covers my installation experience with the first one, the Mighty Mule FM231. (I’ll review the other more expensive one, the Dakota Alert, later on).

1. Mighty Mule (FM231)
2. Dakota Alert

(view on amzn)

The Mighty Mule is comparatively the most affordable magnetic driveway alarm, and doesn’t require a professional installer (neither dose the Dakota Alert).

Briefly stated, it’s a vehicle sensing driveway alarm. It uses a metal sensing probe. It only detects moving metal. You can bury the probe, or simply place the probe near the area to be monitored (that’s what I did with one of mine on the edge of the driveway, which works fine).

It will alert when a VEHICLE is approaching – without false alarms (see below for what to do if this happens).

Know when vehicles approach your home, property entrances, business, or farm. 

(UPDATE 1 year later – read at end of post)
(UPDATE 2 years later – read at end of post)

#1 Reason Why I like This Magnetic Driveway Alarm:

Security. It does not issue false alarms for animals, blowing tree branches, or other non-metal objects that move past it. I only want to be alerted of VEHICLES approaching on my long driveway road.


The ‘Mighty Mule’ company (no affiliation with this blog) designs devices for automatic gate openers. They also design a driveway alarm using their same electromagnetic sensor technology.

Why the Mighty Mule Magnetic Driveway Alarm is the Best for the Money

No False Alarms

The reason why most ordinary motion sensor alarms issue false alarms (animals passing by or the wind blowing tree branches or bushes, etc..) is because of the type of sensor that’s used. Such as those which throw an interruptible ‘beam’ or the type that senses IR (infrared) thermal heat signature. The Mighty Mule uses another type of sensor…

Sensor Detects Surrounding Magnetic Field

Some might call this a magnetic driveway alarm. The Mighty Mule utilizes a sensor ‘wand’ specially designed to ‘sense’ its surrounding magnetic field and any disturbances to that magnetic field in the driveway. It senses metal.

The sensor wand is designed to be buried out of sight – several inches deep, up to 12 inches deep – along side the roadway or driveway. It is connected by way of a weatherproof cable to a transmitter device which is also weather proof.


Driveway Alarm Transmitter

The driveway alarm transmitter uses two ‘AA’ batteries (use these Lithium batteries for best performance!) to send its signal to the receiver which is located inside the home.

How It Works

When a vehicle passes by within 3 – 12 feet of the electromagnetic sensor, the disturbance in the magnetic field (via the metal of the vehicle) triggers the transmitter to send an alert / alarm back to the receiver.

Driveway Alarm Indoor Receiver

An alarm sounds from the indoor receiver which has an adjustable volume control – letting you know that a vehicle has passed by the sensor.

There is also a low-battery indicator on the indoor receiver which lets you know when the transmitter batteries need to be replaced (a nice feature!).

The receiver also has an LED that lets you know that the device has been triggered (in case you missed the audible alarm due to being somewhere else), and it will remain lit until you press a ‘reset’ button. This is another nice feature letting you know that a vehicle has passed by the sensor when you were away.

Great Security For Private Driveway Or Private Road

I happen to live at the end of a private road. It’s nice to know when a vehicle is coming down the road. Having this driveway alarm is especially comforting for ‘the middle of the night’ when there certainly should be no vehicle approaching. If the alarm is ever triggered in the wee hours of the morning, it will ‘buy time’ to get prepared for whatever may be heading this way…

Driveway Alarm Transmit Distance

The ‘Mighty Mule’ specification indicates that this magnetic driveway alarm will transmit up to 400 feet (ideal conditions). My testing reveals closer to 300 feet in general.

(If you need more range, see the alternative equivalent product at end of article – the Dakota Alert)

My own installation is at a distance of 330 feet line-of-sight to the receiver. There are a number of trees in the way, and it works solid from there. I tried further out, but the road dips down and becomes out of ‘the line of sight’ with the receiver (and there are lots more trees in the way) at the 400 foot mark.

When I tested the distances (do this before digging the trench!) the 400 foot distance was marginal for me so I brought it in closer to be assured of a consistent signal.

For a longer distance (sooner driveway alert), I also installed the “Dakota Alert” which transmits a lot further. But it costs more (another review for later).

Mighty Mule Magnetic Driveway Alarm Installation Tips

Sensor on the Right Side of the Road

Given it’s sensitivity radius, install the magnetic sensor wand on the right side of the road. This will better detect vehicles driving “in” to your property.

Magnetic Sensor Orientation With The Road

Orient the sensor wand parallel with (in line with) the driveway.

Best Line Of Sight

Try to get best ‘line of sight’ between the transmitter location and the receiver. The more trees, buildings, walls, the less effective distance. For example, my receiver is setting on the bedroom window sill which faces the general direction of the transmitter.

Inserting the Transmitter Batteries

The moment when you insert the ‘AA’ batteries into the transmitter, it ‘takes a snapshot’ of the surrounding magnetic field via the sensor wand’s current position.

It uses this reference ‘snapshot’ to detect subsequent differences in the magnetic field which will trigger the alarm.

So, when inserting the batteries for testing (and when inserting the batteries for the last time after you’ve completed the installation) be sure that the environment within at least a 15 foot radius does not include ‘non-typical’ metal objects. For example, a shovel setting nearby, etc…). Just make sure the area is clear when you insert the batteries.

Transmitter Support Post

Once I had determined the location for the transmitter and after I dug the trench for the wand, cable, and support post, I set the plastic support post (of the transmitter) in a shallow dug hole and added a puddle of ready-mix concrete for longevity and support. Then I covered the concrete with some dirt on top for the grass to grow.

Paint the support post and the transmitter cover to match your surroundings. I used a ‘forest green’ spray paint.

Mighty Mule Driveway Alarm False Alarms?

If your Mighty Mule keeps giving you false alarms, it is most likely because someone else within range has one too. Or there’s some form of radio frequency interference with another device using the same frequency. It’s easily fixed. All you need to do is change the little micro-switches on the transmitter AND the base unit to something else. Just make sure they match each other.

Mighty Mule FM231 Manual

( Here’s a link to the manual )


An important aspect of overall preparedness is security. Depending on where you live and the layout of your property, the Mighty Mule Driveway Alarm might be just the thing you need for your own security.

 UPDATE 1: My magnetic driveway alarm has been installed for more than a year and I felt compelled to followup with how it has been working out for me:

The driveway alarm has been working great! The performance of the product has been flawless and I continue to strongly recommend it.

It has been very beneficial to be notified of a vehicle approaching on our private road – no surprises when a visitor shows up…

UPDATE 2: I now have had the Mighty Mule FM231 magnetic driveway alarm installed for several years. I simply replace the batteries once a year and it keeps on working!

I have also installed a Dakota Alert further down the road (it has longer range, but it costs a lot more). So now I have a double alert. It’s nice because if the 2nd alarm doesn’t go off, I know they’ve turned around (usually after the ‘Private Drive’ sign).

I’ve also replaced the batteries with these – better for cold weather performance: Lithium AA Batteries

For your interest, here’s an alternative driveway alarm which is specified for up to 1/2 mile away. It’s more expensive, but if you’re looking for distance beyond 400 feet (the Mighty Mule), then this one’s for you:

Dakota Alert DCPA-4000
(view on amzn)

[ Read: Security Tips For Rural Property ]


  1. Ken,

    I’ve seen that system and consider purchasing it. But speaking for myself… I want to know if I have non-vehicular traffic on my property, especially at night. I don’t care if it’s a crackhead or a coyote, I want to know they are there. Mostly because it’s only about 50 feet from the edge of my driveway, to where I lay my head down at night.

    For the expressly stated purpose, I have to agree that you made the best choice.

    For my purposes, I use Skylink PIR at home and Chamberlain narrow beam, focused PIR heads at work. Those are staggered across four points, so we can tell by the number of beeps, how far they have progressed into the property. Sometimes we have corporate espionage concerns. They have been known to arrive both on foot and in a vehicle. In either case the number of beeps tells me which door to go to inside the building, to intercept and greet them.

    1. I too have a set of Chamberlain heads (and the base station). They do serve their purpose as well. Problem though with where I currently live – is that they will often be triggered by deer, bears, coyotes. Unfortunately it can’t distinguish a human from the rest ;)

      Chamberlain Wireless Motion Alarm and Alert System

      But if SHTF, I will have these enabled in strategic locations anyway – better safe than sorry…

      1. Several people I know use heavy steel sheet metal, 1/2″, cut in rectangular strips about 4 inches wide and 6 feet long installed on each inside of entrance doors bolted from the inside to the outside of the house using heavy threaded rod.(from the outside all one sees is a few paint matched washers, bolts, with nuts – like hurricane hardware.)

        On the inside are welded to strips 4-6 inch wide rings of heavy pipe though which heavy pipe can be slid across behind the door. Three or four heavy pipes slide across in a row spaced from top to bottom behind the entrance door and you have a lot of security no one can come through. This allows the door to be very slightly breached to dissipate direct or indirect force but still not entered through.

      2. Ken, What are Chamberlain heads? I like the system you mentioned for vechicles,but want to know about foot traffic as well.

      3. Also, is there a water proof Motion sensor that detects foot traffic that you know of? I can place around my property?

        1. The Chamberlain alarm system (detectors) are waterproof (from rain, etc..). I’ve used them for years without issue.

  2. We had a driveway alarm many years ago that also would only detect vehicles not critters. One day the alarm went off and I went into the kitchen to see who was coming down the driveway. Well there was no one there, so I went back to what I was doing. A couple of minutes later the alarm went off again, back to the kitchen, again no one there. After a third false alarm, I stood there waiting. It turned out that DH was driving the riding lawn mower too close to the sensor setting off the alarm. It was good to see that even a small vehicle set it off, however I learned to turn off the alarm every time he went out to mow.

  3. Ken, does the base station have the ability to be battery powered if the electricity goes out? Camberlain “CWA2000” has that feature.

    1. All of our Mighty Mule gear is solar to battery powered. Completely off grid.

    2. @Who Knows,

      That’s a negative. For me it’s a non-issue given that I am powered via solar and off-grid batteries w/ inverter.

      However, the ‘wall-wart’ secondary is 12 volts DC, and therefore could be rigged up to a 12-volt battery (which would probably run it nearly ‘forever’…)

      So for SHTF, it’ll work with that modification.

  4. As with McGyver, I am more concerned about foot traffic than vehicle traffic. Any vehicle coming into the community has to come down an 11 percent grade at the front of our property. Our property is the only fully fenced/cross fenced in the community. So, if they slip or slide on the grade for not knowing how long (and winding) it is, then we know they don’t live here! And if they go too fast and can’t hold the turn at the bottom, well, then they end up in our fencing!

    They still have another 1/2 mile back uphill to get to the driveway, which has a coded mighty mule on the gate, and a sensor that announces their welcome. The driveway is another 1/4 mile, also has sensors (thank you mighty mule) and when they actually pull in to park well, then they get the 4 Schnauzer welcome. HAHAHA

    Because of all the young bears this summer, we have just added two new family members….2 beautiful Great Pyrennes. Too young to be of great service this summer, but certain to assist in patrolling the poultry next summer. We have to be able to sleep. As pups, I am pleased to announce that they let us know first light when our OLDER bear stopped in for his usual hello. They will work out just fine!

    Good article Ken, as usual. Thank you for thinking of different ideas to assist in keeping us all thinking!

  5. I just got 3 door guards so even if they get in, I get a warning as they try to fanagle a way to overcome it.

    I am like most-what if they come through the field, the back way??

    The door guards were bought after we had the first burglar/assault in 30 years in this area. It was less than a 1/4 mile from our street. I read a review and the cop said the door guard was the only reason the burglar didn’t get in…so I bought 3.

  6. Thanks for the article on rural security Ken.

    It reminds me of the several times people have tried to rip off an old Willy’s jeep that was still running and used on the farm to pull the trailer for irrigation pipe. My uncle’s farm was close to a busy road so people used to pull in to do weird stuff. I remember greeting them with a 12 gauge pump gun.

    It was dove season so the would be thieves were horrified to see all the responding vehicles sprouting 12 gauge shotguns and 1 of the 4 vehicles had a cell phone.(many years ago and we were low tech.) My uncle did not have this gate system.

    A rural cattle ranch I hunted on had this type of gate. I thought they were cool. Great system and the owners were kind enough to grant me the access code.(conditional hunting there. No deer, only squirrels, leave everything else alone.)

  7. When the boys tried to TP more front trees, I woke. They did not know I knew they were trashing our front yard until I surprised them, chased them down, and retrieved a new sneaker off one foot from a nearby yard. Next, day they all came to apologize.

    When the high school druggies hit our neighborhood week after week sneaking through security guards and gates to break into community cars and garages I finally tracked them down after our GE wireless yard sensors kept being tripped.

    When the fed. alphabet soups came numerous times to try and falsely entrap a family member over prepping, knew they were at the door and remained silent. Bully and threats were minimized. Lawyers charge a lot just to tell you to remain silent. Don’t respond. Never. If you are charged, they will let you know. Otherwise it’s just fishing with lies and threats. Very evil.

    Each of these events ended in victory partly due to our sensors and monitor chimes. GE wireless, battery operated, plugin monitor chiming with battery backup. Highly, highly advise to own. We have them monitoring the side walks, front door, driveway, and a few extra areas. They’re highly dependable except for animal false alarms.

    There’s a huge advantage to know someone is coming but they don’t know you know. HUGE.

  8. The best pro-active anti-theft device I have ever used is the unmarked 2003 Ford Crown Vic P-71 parked outside my house. Money well spent. ;-)

    1. Love that, will be headed to the next Sheriff sale to see what I can do on a used patrol car.

  9. Luckily we still live in a small enough town/area not to have any problems. I do know there will come a day when people will get desperate. I am trying to decide on what is the best solution for our area (small subdivision, houses on 1 acre lots, pretty much on the edge of town.)

    There are so many noises, trains, Spacex, and Ft Hood booming all the time, it’s hard to discern threats sometimes.

    1. It sounds like we might be neighbors i think I’m a little north of you. just remember there are over 300,000 people on and around FT.Hood. killeen has a high crime rate already imagine if when it hits the fan. lucky for us we have a lot of like minded people around us. Stay safe

      1. Sounds like I’m near both of you. I’m a little west of Ft. Hood.

  10. I have 2 of these alarms and they have worked perfectly. I have 2 driveways into my place and it has never failed. It is important you don’t have obstructions between the transmitter and the alarm. I did have to set the codes differently or they would set each other off. For a longer drive way they could be set up in different distances to keep track of the intruders progress along the driveway.

  11. Y-all ever seen an “oil patch” road after a good rain? Ruts 12-14” deep, usually washed out in several places when the water builds up on one side to much, twisting and turning around trees (shrubs) and BOULDERS, and add to that a few signs that have been shot all to he11 with everything from a 22 to a 12GA.

    Now invasion that 1500 foot road/driveway heading into an unseen home where a grumpy old fart is believed to live with a 115# mean-azz dog that eats cows whole.

    Now top that with a few Cameras (fake), No Trespassing Signs 1/2 falling off the post, a couple to trees that look to be falling over the road at any time, and a Fat-Old-Grumpy-Man that answers the door to the Jehovah Witness wearing nada but his underwear holding a beer and a shotgun (actually happened).

    Needless to say I don’t get many “uninvited” guests…. And you sure as heck better have a 4-wheel-drive HAHAHA

    Reputation in the neighborhood is everything :-) :-)


  12. For the you that still want to monitor foot traffic but can not discern between animals and humans, I have a method that works for us. I place a monitor at the foot of the drive (about 150′) and then another about 30′-50′ closer to the house – an animal seems to favor crossing the drive to go from treed areas to treed areas rather than following along the drive. Only people travel through both monitors so I know when to shoot (kidding). One chime is a tree rat or deer and two chimes, an interloper.

  13. We have the Dakota MURS Alert system. Two on the driveway with different alert signals so we know the difference between a deer (one alert) and a car (two alerts). If keeps you from getting complacent about false alarms in the middle of the night, if you hear the second alert it’s time to rack the 12 gauge.

    The system is set up for 4 different alerts, also hand helds. Between the dogs and the sensors, if you can get to my place without me knowing it, you parachuted in.

    1. I just installed a Dakota Alert drive way alert system on my 1200′ driveway. I ‘ll expand it over time to include a second driveway alert and multiple motion detectors. Sure wish I could reprogram those stupid chimes.

  14. I had a gravel driveway. It’s now covered with asphalt but with the original gravel as part of the base. To make a long story short a few years ago I dropped some nails on the gravel and decided to pick them up with a magnet. a lot of the gravel came up with magnet. Iron ore in it. Is there a sensitivity in the device that can be adjusted for this? Thanks. Current sensor is a schnauzer nut he’s not all that reliable.

    1. The ‘Mighty Mule’ sensor is such that regardless of the existing metals which may be around (our beneath) your driveway, it will not be a problem because the way it works is as follows:

      When you insert the ‘AA’ batteries into the transmitter, it ‘takes a reference snapshot’ of the surrounding magnetic field via the sensor wand’s current position. It uses this reference ‘snapshot’ to detect subsequent differences in the magnetic field which will trigger the alarm. So if the reference includes those nails that you’re referring to, they will not set off the alarm… unless you move them. If you do, then just take another reference snapshot by removing the batteries and re-inserting them.

  15. Big mean dogs outside, little yap yap dogs inside. Don’t let the vet do anything to them that would make them trackable or treat them with anything to decrease their natural responses.

  16. My driveway alarm system I put in eight months ago , I put in a Dakota alert Break Beme wireless driveway alarm that is solar powered at the transmitters , The transmitters can be placed up to 300 feet apart end it uses 2 infrared beams both of the beams have to be broken to trip the alarm, these transmitters can be up to a half mile away from your receiver depending on ground Conditions , when I installed the system I calculated the height of a deer head Of A mature dear placing the beam above this but still to get tripped by a small compact car , in the eight months I have had this unit I have not had one false alarm but not one car or person walking down the driveway get through it Without Setting the alarm off , and you can also get handheld receivers if you’re out on your property to receive alerts , and I believe you can have up to four different transmitters working at the same time and each one will make a difference sound as they get tripped

  17. I have the same system Ken and it has worked as advertised. I have two driveways entering my property that connect at a Y. My one driveway is very wide and I had to put 2 alarms opposite of each other to cover the entire road. I have caught many people sneaking in late at night and in the middle of the day. My alarm even picked up a guy on a bicycle who had no business on my property. My security system has many levels but the Mighty Mule driveway alarm has worked perfectly. I did have problems with the receivers when I tried putting them next to my computer, so I moved them to another room which can be hard to hear if at opposite end of my home. I would like to see adapters for portable alarms which could be set in other areas of the home.

  18. Have pressure sensors in two locations that do not work on anything under 1000 lb. Add three day and night cameras in trees and a twenty five foot pole at the front gate solar powered with a little red light. It’s funny to see people drive by and look up and know there on camera. Going to order a few of these Mule units as I think their better than what I’m using. Hope these don’t get out of country as they could be used as trigger for IED also.

  19. Thanks for bringing this up the BuddyBar. Mr. asked me to get a couple of door jammers awhile back, but the only ones I saw looked flimsy. These look well made.

  20. Our first detector is the neighbor’s huge lab that barks at all unknowns. Second alert is our dog, who can hear everything when it starts at the base of the hill to come up to our property. And she can tell the difference between vehicles – friend or foe (all that are not already designated as friend).

    1. I agree with you on the dog. My dogs can tell a strange vehicle a half mile away on gravel driveway. They know how everything should sound, smell, and they can instantly spot somethin out of place. Just like a coon in a tree, they are in “their element”. I would trust em with my life.

  21. I have had the mighty mule for over a year. Always wondered why the ups truck most often did not set it off. Our ups driver does drive fast. Who knew. Otherwise it is a great device.

  22. Can you add multiple sensors to one receiver?
    I have a driveway that loops with 2 entry points but I only want 1 alarm.

    1. Rob, Yes, I believe that if both sensors/transmitters are set the same with the receiver (dip switches) that it should function as expected. I may be adding an additional sensor/transmitter on my road too…

      1. Yes and if you have an automatic opener by mighty mule you can set the warning receivers to a different frequency than the gate opener transmitters

  23. On the Mighty Mule, how long is the cable that goes from the sensor to the xmtr?

  24. Ken;
    We have had a Dakota drive way sensor for about 4 1/2 years and are pleased with the system . The cord length from the in ground sensor to the sending unit is about 50 feet long . Our house is about 160 feet from the sending unit. I recommend the Dakota as a great unit .

    1. I too have the Dakota Alert, at the beginning of our road property line (much further away than the Mighty Mule). I really like having two of them!

  25. I’ve had a Mighty Mule for about 7 years. Replace the batteries every year before winter, but finally had to replace the transmitter unit 2 years ago.

    I find I have to turn it off if anyone is mowing and going back & forth near the driveway, since it will detect the mower as a vehicle. It sometimes even detects the little pull cart I use for gardening. The only vehicle I’m aware it’s been unable to detect is the occasional FedEx/UPS truck when they drive like a bat out of he**. I suspect the tires may not even be in contact with the gravel as they come up the drive!

    The Dakota Alert might be a Christmas present for my cousin given the scare he had over Labor Day weekend (late night visits from blacked out cars). His driveway is much longer than mine, so the extra distance the Dakota can reach might be helpful for earlier warning. Of course, I gave him a Mighty Mule several years ago and he never installed it…..sigh…..until two weeks ago (it had to be installed closer to the house)!

  26. I don’t understand how you DONT set the alarm off when you get in your car and drive to the store ect.. Doesn’t that trip the alarm when you leave… how do you re-set it when leaving so you can know if someone has come while you were away?

    1. Yes, any vehicle will trip the alarm chime. I should have mentioned that the “alarm” is actually a chime, tones. It doesn’t continue beyond the initial sound. It plays the tone, and then stops (not continuous).

      However I believe you’re actually wondering how you know if another vehicle came in while you were out. In that case, there’s no way to know.

      On the Mighty Mule driveway alarm receiving unit, there is a red LED light that remains on after it has been triggered, until you press a button to reset. This simply lets you know that the alarm was triggered. When you leave in your vehicle (and when you return), the alarm (and light) will trigger. So if someone came in-between your trip, there’s no way to know. That’s when you take it to the next level with cameras, etc..

  27. Our residence is stick construction but with metal siding and roof. The garage/shop doors face the road to the west (driveway is 600’+) so the residence is at the back of the building (at the east). Will the receiver pick up the signal in a metal building? There are no windows on the west side of the residence because it is all garage/shop, so we have no window sill to put the receiver in. Can the receiver be mounted up under the eave facing the road, and then hardwired somehow into the residence (about 30′ from the front of the garage/shop)? What driveway bell would you recommend for this application.

  28. After working just fine for 18 months, Mighty Mule FM321 gave couple false alarms and just stopped working. No signal for passing vehicle. Changed batteries, changed the codes – no result. Cable from metal sensor to the sending unit is fine. Receivers (I have two) seems working fine, but sending unit is not sending. There is no replaceable parts , so now it’s just a piece of junk. After about 18 months…

    1. Ray,
      Did you check all the fuses? Yes, they are likely there on the circuit boards. Check continuity on any buried or conduited lines. Might also see if there are any long term batteries for memories on those boards. Have seen them give out. Then get online and do the search for issues with your model, others may have in your position and found answers. Dont give up. If someone built it, it can be repaired.

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