rc plane locator

[John t]

Hello I'm trying to build a circuit for finding a downed rc airplane around a 555 chip that when turn on just before taking off would admit a chirp or
buzzer say 2 to 4 times then be silent for 30 second give or take a few then cycle again I've tryed numerous configurations with no results
Help  please...

 

[IconicPCB]

Try the following


https://www.google.com/search?q=fox+hunt&ie=UTF-8&sa=Search&channel=fe&client=browser-ubuntu&hl=en&gws_rd=ssl#channel=fe&hl=en&q=rf+fox+hunting

Should give You some insight into the problem

[Richard Crowley]

Yes, the traditional way was to use a "beacon" which you could triangulate on with direcitonal antennas (aka. "fox-hunting").
The 21st century way is to use a GPS and a transmitter which will broadcast the exact location so no searching is necessary.

There is a whole sub-culture of amateur radio ("ham" radio) called APRS (Amateur Packet Radio System or Automatic Packet Reporting System)
And a subset of APRS which uses very small GPS receivers and APRS transmitters to allow you to track almost anything on the planet.

Depends on which is more important:  the activity of searching and finding the lost craft, or simply locating it for rescue.

APRS overview:  http://en.wikipedia.org/wiki/Automatic_Packet_Reporting_System
APRS website: http://www.aprs.org/
Typical APRS tracking beacon: http://www.bigredbee.com/  (one of many)
Typical online APRS tracking map: http://www.openaprs.net/  (one of many)

OTOH, to answer your original question,  it is common to use a DUAL 555 where the first one implements the timeout (30 seconds or whatever), and the second one actually generates the locating tone.  You would want to tune it to the resonant frequency of a small piezoelectric transducer for maximum audible output at minimal payload weight/mass.

[Jeroen3]

You can already buy those beepers. They will start beeping when there is no change in servo signal for an amount of time.
For less than the time you'd be spending.

We call them corn-beepers. Since when you lose the rc plane in a corn field you'll have a hard time finding it again.

[kaindub]

I contributed such a project to elektor magazine. It was published in April 2013.
I used a picaxe to generate the signals.
Robert