AM/FM SOS Beacon Saves Your Bacon


[BadWolf] sent us a device called the “Bacon Beacon“, which is his 555 Design Contest entry. In short, it’s a life-saving device that emits an S.O.S. signal in Morse code over both the AM and FM bands. The device uses five 555 timers to get the job done, each of them dedicated to a specific task. Three of the timers are used for clocking and Morse generation, while the remaining two are used to produce and transmit an audible signal over the air waves. Currently, the signal can be received about a mile away from the source, which would theoretically allow for a search and rescue team to locate you with a simple radio and directional antenna.

The current design is still a bit rough around the edges, but the final plans would have the circuit built into a flashlight-like device equipped with red and green signaling LEDs. It’s a clever project and would make for a great tool if you got lost while hiking, or in the event of a zombie apocalypse.

Stick around for a quick video of the Bacon Beacon in action, and swing by [BadWolf’s] site if you want to know why his project has such a strange moniker (hint: it’s not because it can “save your bacon”).


26 thoughts on “AM/FM SOS Beacon Saves Your Bacon

  1. So he could have done it with a bunch of 555’s and passive components, or… he could have done it with a ~$1 low-power microcontroller? Using something like an MSP430 would not only fit in the flashlight better, it would also use much less power!!!

  2. @Ekaj

    Sure using a gps and a well designed FM transmitter and voice generator would have worked.It’s on revisiona s we speak btw ;3

    Fact is,this has to be made using only 555. The aim is also to show people how to work using time graph and logic to achieve something with simple parts.

    I hope the explanation and examples I gave will lead people into this way of thinking,as I think it’s one of the most efficient.

  3. I’m no pro on SOS-beacons, but know a little morse. there is no delay between the “words” and letters in this transmission. it sounds a little like this:
    In my opinion it should be:
    Not sure if I’m right, but I know the letters O (—)and S(…) and could hardly decipher in this transmission because there were no silences between it.
    Other than that: I wish I’d be so handy with electronics. It would complement my arduino skills…

  4. @Bioz
    True,that’s why in the demo the power is limited to a 10 meter-capabale signal.

    If you take a look closer you’ll see that all the 555 are wired almost exactly the same in an ordered manner to avoid confusion.(imagine if it wouldn’t lol)

    I had no 556 on hand+short delay for the contest.

    I’m pretty sure that anyone hearing a continuous stream of Ss and Os would understand the meaning,even without a space in between.

  5. I have guard at 121.5, and 243.0

    New SARSAT freqs are 406 mhz.

    Anyone fool enough to depend on a “homebrew” device for life/mission critical usage deserves what they get.

    Buy a damn ELT, or EPIRB and have it registered so the owner can be identified when it’s tripped.

    I disagree with the presumption that broadcast band users would understand the meaning of the morse code signal. Heck, my wife would just tune away if she heard it ! The ‘average joe’ would be annoyed that they can’t pick up their pop music station.

  6. “Anyone fool enough to depend on a “homebrew” device for life/mission critical usage deserves what they get.”

    Remind me not to count on you if something happens. I know it would be stupid to only count on this but when your in an emergency and you want someone to come to help you, you want to broadcast as many ways as you can. If i heard SOS i would actually try to help if i could.

  7. I have to agree with the people pointing out that transmitting SOS, no matter what the output power, is TERRIBLE idea. Radio amateurs have shown that you can transmit across contents on milliwatts,. ESPECIALLY in CW (the modulation that you use to send morse code). Once you send an RF signal, especially on MF or HF, you really have no control over the range.

  8. Interesting hack to be sure. Very cool idea but I think it would be of very limited value for life saving and wonder how legal it is.
    1. You are transmitting on commercial bands. Isn’t that illegal? Yes in a real life or death issue who cares but if it goes off in error?
    2. The range is only around one mile. A whistle will carry for at least that far and are cheap and take no batteries. Not enough people carry something like a good old fashioned whistle when out in the woods.
    Yes there are times when when this would work best but they are few and far between.
    Just because it isn’t supper practical doesn’t mean that it isn’t cool.

  9. You don’t need a directional antenna to do S&R on a beacon like this. Haven’t you ever seen circle-walking?

    If trapped in an avalanche, sure the directional antenna will save time. In almost any other circumstance an omnidirectional antenna and some patience (and intellect on the part of the rescuer) will do.

  10. @BadWolf and Hacky

    Even though it is a series of S and O it isn’t “proper” international Morse code.

    From the International Morse Code:

    “1. A dash is equal to three dots
    2. The space between the parts of the same letter is equal to one dot
    3. The space between two letters is equal to three dots
    4.The space between two words is equal to seven dots ”

    So for your code to be considered “right” it should have the timing as shown above.

    Plus it’s always good to have standards. :)

  11. OK, help me out here… is the 555 part of the circuit the keying circuit, or the modulator/transmitter part of the circuit, or both? I took a quick look through the link, but didn’t see a full circuit diagram…

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