Find A Drone

Flying a drone usually leads to–sooner or later–crashing a drone. If you are lucky, you’ll see where it crashes and it won’t be out of reach. If you aren’t lucky, you’ll know where it is, but it will be too high to easily reach. The worst case is when it just falls out of the sky and you aren’t entirely sure where. [Just4funmedia] faced this problem and decided to use some piezo buzzers and an Arduino to solve it.

Yeah, yeah, we know. You don’t really need an Arduino to do this, although it does make it easy to add some flexibility. You can pick two tones that are easy to hear and turn on the buzzers with a spare channel or sense a loss of signal or power.

The device has its own battery so it will work even if the drone’s power depletes. Apparently, the 9V battery will run the whole thing for over 20 hours. Pulsing the audio would probably push that number even higher. Of course, the downside is the drone has to carry the extra weight, but if you recover an otherwise lost drone, that might be a small price to pay.

This might be more practical than a calculus-based approach. Maybe like a tightrope walker, you’d rather use a net.

56 thoughts on “Find A Drone

    1. Drawback: Attach new and charged battery. Crash 1 minute into flight. Chill for an hour or two until the battery is low enough to trigger the LiPo saver alert.

    1. ok, with < 45mA @ 5V it is plausible to get a 20ish hours of operation out of a 9V battery with a 500mAh capacity, not accounting for the loss in the generator. At 20mA @ 5V it could probably last 20h on the battery.

  1. I’ve used a bright led arrow notch connector for an RC helicopter. They stay lit for about 2-3 days and are designed so you can find lost arrows. Visual only but bright!
    And they weigh practically nothing. I’ve never lost my helicopter, but that’s because it won’t fly right now hahaha. Never got the opportunity to have to search for it. :(

  2. If your flight controller isn’t retarded it will have provision for a buzzer that can be activated via a switch. That’s usually more than enough to find it if you are flying LOS.

    1. Batteries die. Crashes break things. Main receiver might not work.
      Maybe the transmitter fails mid-flight and the signal is lost. So a homebrew backup search-assistance device is a fantastic idea.
      How is that? Counterpoint please.

      1. >Batteries die.

        Not very often if you look after them. And the same could be said of the 9v battery this thing uses.

        >Crashes break things. Main receiver might not work.

        If the RX signal is lost the FC should activate the buzzer. Cleanflight does this.
        And usually your receiver is inside the model so damaging it is very unlikely.

        >Maybe the transmitter fails mid-flight and the signal is lost.

        See above. If you have a “drone” and don’t have your failsafe setup properly please stop flying before you hurt someone.

        >So a homebrew backup search-assistance device is a fantastic idea.

        It is a good idea. Hence most of the multirotor control boards have that functionality already and you can go on hobbyking etc and buy a lost model alarm (very loud ones too) for a few bucks. And a lot of ESCs with will make a beeping sound with the motors if a throttle signal isn’t present for an extended period of time.

        Buzzers are pretty much useless if you crash far away though. As soon as the model becomes a little spot off in the distance finding it will be pretty hard. Especially if it crashes into something and the buzzer gets covered.

        If you have a video transmitter you can use the quality of the signal to find the model much much easier.

        >How is that? Counterpoint please.

        You don’t seem to have much experience in this field. If you do I guess your “drone” or “drones” aren’t really setup that well and you’re a danger to people and property.

        1. No, I don’t have much experience. Just a $200 helicopter that I keep within sight about 30-40 feet off the ground.
          I am a safety-first kind of guy, I just have a cheap beginner heli.
          No gps. Not a ‘drone’. Admitted newbie.
          I didn’t know that the latest and greatest could do all that. But some people have a bare bones setup.
          I just felt that you were assuming alot and s-ing all over a reasonable backup system. But you make it sound like all $400+ FPV have it all figured out.

          1. >I just felt that you were assuming alot and s-ing all over a reasonable backup system.

            The point is you shouldn’t need this on a reasonable setup. Adding extra boards, batteries etc to do a simple job that the FC can already do is just adding complexity. You really really really don’t want to have multiple batteries to worry about. You don’t want extra weight if you can help it. You don’t want extra wiring extra if you can help it.
            The great thing about multirotors over fixed wing and helis is that there is so little to fail. No linkages, no servos etc.

            >But you make it sound like all $400+ FPV have it all figured out.

            Everyone that is flying a multirotor should have a buzzer for low battery/status/lost alarm. You get that with a $17 flightcontroller and a $1 buzzer. Everyone that is messing around with RC models esp. flying ones and ones with glow engines should know what fail safe is and have it setup properly. I know the CC3D controllers don’t have a buzzer connection.. so those are in the “retarded” category.

          2. My ~$100 FPV quad is capable of turning on a buzzer/small alarm. Spedix S250AQ off hobbyking with a cc3d. So basically all $100+ FPV have that figured out. And your $200 heli probably has aswell, it must have a flight controller of some sort to which you can attach something very loud.

  3. Even I’ve ‘reinvented the wheel’ so to speak on more than one occasion, the latest being an RC servo switch I built using a Picaxe microcontroller controlling a high power MOSFET so via the transmitter I can turn on/off a 50 watt LED hanging underneath my quadcopter, but in this case you can’t easily beat this lost model alarm for its compactness, weight and flexibility:

    The addition of the weight of a 9v battery will certainly hamper the flight time and performance of smaller quads.

    1. Personally I’d drop the 50w LED and fit a small video transmitter and camera. If you don’t fly FPV the tiny CMOS cameras will be enough… Then when you lose the model you can see what it landed in/use a directional antenna to find it.
      The old guys in my club are buying pre-built 250 size quads with FPV equipment pre-installed even though they don’t have goggles or similar to fly with.. we’ve used it to find the quads after they lose orientation and fly off into the horizon a few times now.

        1. >How’s that CMOS cam going to work at night, señor?

          You shouldn’t be flying when it’s getting dark as you know .. it’s getting dark. Safety 101 killo (Bonus points if you know what type of “spanish” that is). Also video transmitters don’t stop working in the dark so you can still use the signal to find the model.

      1. I currently have a Z1 Tiny2 gimbal with Xiaomi Yi attached to it, and a few days ago I received some 5.8ghz TX & RX parts so I can view the output of the camera on a screen attached to the controller (when the screen arrives…)

        The 50 watt LED goes in place of it. All for a bit of fun night flying, I won’t go very far away with that LED on.

        This is what I get with that gimbal+camera. I know the landing gear gets in shot, might upgrade to retractable landing gear but currently working on a 450 sized quad with larger landing gear that won’t get in shot:

        1. Mere words cannot describe how beautiful that field looks!
          Now I actually DO want to buy a professional setup like that. I didn’t think the landing gear detracted much from the video, >90% good shots. I would thumb-up on YouTube if I had an account, licensetodrive. Interesting music BTW; very ???-don’t know, not what I listen to but I like it.

          1. “Mere words cannot describe how beautiful that field looks!”
            It looks better from higher up in a glider from either of the two gliding clubs within 5miles.
            It looks pretty good from ground level, especially when driving around the “wild” cows that have decided to lie down on the roads :)

          2. Tom G, small world :)

            It’s funny just how much the cows don’t give a damn about the vehicles going through ‘their’ land, making drivers wait whilst they cross the road, usually very slowly.

          3. Oh, I don’t mind if they actualy *cross* the road, however slowly. Lying down and chewing the cud is plain antisocial.

            Most entertaining sight was when there was a queue of cars at the main T junction on the common near Minch, and one cow suddenly noticed the others had disappeared over the brow. It suddenly developed a herd instinct and zigzagged between the queuing cars, hooves slipping in all directions.

            Always nice to have a Winstons icecream, and watch the sun set over Stroud.

        2. Come on dude, that’s not a youtube drone video, you have the banging beats but no flips or rolls, you need to put your rates up man. (FYI notarealemail I’m joking, don’t get your pants in a twist).

          Your cx20’s battery would look like a puffed up sausage by the time I had finished with it.. :p *

          *for people like notarealemail that can’t get jokes; I would fly pitched forward almost vertical and at full throttle doing flips causing the 25C or whatever it is battery in there to get hot and puff.

          1. The CX-20 is not known for its speed, unless there’s a fault / crash and then it can go really really fast, straight down :)

            Luckily I haven’t crashed mine yet, just a few iffy landings. Though I did experience a crash with my 450 sized Ifly4, whilst yawing in one spot it leaned off to one side falling out the sky and smashing into the back of my shed with a loud bang. Landing gear broke, props broke, (crappy) LEDs broke, but all fixed/replaced and up and flying again. The frame is really tough.

            FPV racing is my next challenge once I’ve got my fill of recording footage with gimbal held cameras.

  4. Personally I’d go with ESP8266 with smallest GPS receiver and small Li-Po battery (and maybe a small buzzer) on the drone and ESP8266 with high-gain antenna and some display to act as receiver. That setup will give me a 3-4 times the range of buzzers, would use much less power and will be accurate to few meters, depending on the quality of GPS module and terrain. With small buzzer location alarm can be enabled remotely. This has an added bonus of not attracting potential thieves and tracking them if they actually steal the drone. ESP8266 can even connect to any open network in range and send current location via web server in case it’s out of range of receiver. A smartphone app can use this method to show location on map…

    1. That sounds great but a thief may unplug the battery.
      Better put a dye-bomb in there hahaha. I can’t think of a good way to track a stolen item. If the device is still working after someone snatched it, at least you know the thief is a dumbass.
      Unless you have that device well hidden, which probably you do.

      1. That’s why suggested secondary battery for this module only. Put it in black box and make it look like part of quadrocopter body/frame or some important part. No one will have time to disassemble it, and won’t suspect that this is a tracking module…

    2. >ESP8266 with high-gain antenna and some display to act as receiver.

      Or just go for a radio system that has telemetry instead of adding another transmitter on the 2.4ghz band right next to your 2.4ghz RC radio. Even futaba (expensive) have a radio with telemetry that’s less than $200 now (T6K).

      1. Almost everything I own is worth less than $200, so I naturally think cheap and clever instead of throwing more money on the problem to solve it…
        My idea is to wake up every second or so (using PPS output of GPS module), connect to receiver or nearest open network, send coordinates and go to sleep.

        1. Can it really do that in less than 5 seconds? My router takes like 4 seconds for connection to phone. But maybe it’s the phone taking 4 seconds. Just wondering what the connection delay is.

          1. Probably not, but one can adjust, how often ESP reconnects to any network, including receiver module with high-gain antenna, to conserve power. Or just don’t put ESP to sleep and keep it running at all times. The idea is to have 4 times more range, than with even loud buzzer. And even more, if there are open networks in area. I’ve got this idea just minutes before I decided to share it via my first post.,,

        2. “Almost everything I own is worth less than $200, so I naturally think cheap and clever instead of throwing more money on the problem to solve it…”

          By the time you’ve ordered a GPS module and all the crap to make your solution work you’ve spent a bunch of money and time on something that is possible to do and better with one of the higher spec cheap Chinese radios.
          And as a bonus you get telemetry data like battery voltage that is always useful instead of something that probably won’t work when you actually come to need it.

          1. You are right, but you think as consumer/user. Hackers think differently. That’s why [Just4funmedia] made his own solution. He spent some money making something that is worse than $200 telemetry transmitter, because he could.
            With my approach I’d spend less than $20 to make this work, learn things I don’t know yet, and make something useful. And hacking is just fun. Adding telemetry won’t be hard at all, just add it in firmware and maybe connect to main board of drone and/or to battery…

          2. For some reason hackaday hides the reply button after a certain level of comments..


            I’m all for hacking. I added support for telemetry for my Futaba setup to my local copy of cleanflight for example..
            There is a point where hacking becomes a false economy though. If you hack up a lost model beacon that’s cool and all but does that cool factor matter at all when you’re actually flying? Does that cool factor remain when the model actually goes missing and you forgot to charge the extra battery that you added to the system or you realise that actually there aren’t many open access points in open areas (the sort of places that you should be flying) and the whole idea of the beacon connecting to an open access point and sending it’s GPS location is lunacy?

          3. It’s HAD. We make cheap crap better. We implement ideas that the big companies won’t touch. We learn hands on. I want to see this setup built because it means were not all sheep. Sometimes buying $400 worth of equipment and assembling it is worth more than buying the $399.99 thing that every store has.
            And who knows. Maybe we do it to learn how to BUILD something awesome rather than just ‘play’ with it. I don’t want to buy a quad, I want to build every last damn piece possible that I can. Even if it means I give it to someone at the flight club to fly because I am terrible at it. And that person can tell me what a crappy job I did building it.
            It means I learned something, right? And will do better next time. I’m pretty Moryc doesn’t want to buy awesome, he would rather make awesome.

          4. And I was trying to bring up the ‘beacon connecting to an open access point and sending it’s GPS location’ issue up, while you are telling him ‘it sucks buy this instead’.
            I have doubts that sending gps position over an unlikely open wifi and connect to server then 4g to phone would work when you need it. Build a gigantic cantenna array or haha send a swarm of ‘drones’ to search for it.
            Good debate, I’m going to bed. Have a great day everyone!

          5. @notarealemail

            >It’s HAD. We make cheap crap better.

            So hack lost model features into one of the many open radio/telemetry projects that are out there.

            >We implement ideas that the big companies won’t touch.

            Like a buzzer wired to a microcontroller with a battery?

            >I want to see this setup built because it means were not all sheep.

            Yeah man! Lets stick it to BIG RC! Those blood suckers have been keeping us down too long.. oh hang on.. most people are flying multirotors with opensource flight controllers, open source ESCs.. some people are using opensource transmitter firmware and opensource receivers.

            >Maybe we do it to learn how to BUILD something awesome rather than just ‘play’ with it.

            BIG RC isn’t stopping you from going and getting a frame kit, motors,escs etc from banggood or hobbyking.

            >I want to build every last damn piece possible that I can.

            Ok, if this is sooo important to you go and build the buzzer from scratch too. You don’t want to be one of the sheeple that buys a commodity buzzer that has a good MTBF from BIG RC. You wouldn’t want it to actually work when you need it.

            >And that person can tell me what a crappy job I did building it.

            The great thing about multirotors is you can build a frame out of sticks and string and as long as the motors are about the same distance apart and it will probably fly.

            >I’m pretty Moryc doesn’t want to buy awesome, he would rather make awesome.


  5. “The worst case is when it just falls out of the sky and you aren’t entirely sure where.”


    The worst case is when you can determine where it landed because someone is screaming in agony. Seen that with r/c aircraft half a century ago.

    Or like this (very gory) picture:

    Some people don’t realise that drones can be dangerous.

    1. > Some people don’t realise that drones can be dangerous.

      Because some companies (looking at you two, DJI and Parrot) attempt to sell these things to everyone marketing them as easy to use hassle free toys. Just stick a battery up the devices arse, do the calibration dance, press a button and it will magically rise.

  6. Nice! After I lost one of my drones in the forrest (never found it back). I build nearly the same thing with an esp8266 running from a small extra lipo (that voltage seems to be fine). It weighs nearly nothing (exept of the lipo). Plus I can search for that wifi signal with wifi analyser app on my smartphone. esp8266 wifi range is pretty impressive.

  7. silverx did a great job by spinniing the brushed motors every few seconds in the Floureon H101 dual/acro formware wich resilts in a very high beep like tone. Will never loose that quad!

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