Audio lost plane beacon - finder; locator - RC Groups
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Jul 08, 2004, 06:33 AM
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Audio lost plane beacon - finder; locator

Aother version of an old device.
Plays Obladi-oblada at power-on and when servo signal is absent or bad.
Stops playing when signal resumes.
Only 2 components: PIC 12F629 and piezo transducer.
Plugs as a servo or in parallel with. Maybe better to add a ferrite coil on servo cable.

Download link in 'Article' at
My club's website
See Audbeac.txt + Audbeac.hex

Also other 'Articles' related to RC model modelisme balise joystick trim expo FMS simulator cable avion perdu record servo (thanks search engines)

If in Belgium or neighbour countries, come and see us at our Air Show

Brussels / Bruxelles / Brussel Belgium

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Jul 11, 2004, 10:17 AM
now that's a wattmeter...
simingx's Avatar
Does it also sound when there's no change in the signal for a long time? This would allow it to be used with PCM receivers, as these output a servo signal no matter what.. Should be quite a trivial task with a PIC inside...
Jul 11, 2004, 11:06 AM
Registered User

And PCM?

Interesting remark, I will investigate and come back.
The design was indeed oriented for PPM transmitters.
Jul 14, 2004, 12:43 AM
Registered User
Please explain a little more in detail for me as I am not
familiar with PIC circuts.
It looks simple enough to build but how does it get programmed to
play the song?
Where are the parts available?
Jul 14, 2004, 12:44 AM
now that's a wattmeter...
simingx's Avatar
You need a PIC programmer for that...
Jul 14, 2004, 03:57 AM
Registered User

PIC programming and development

I know this is a barreer.
If there is enough interest, I could translate some documents I have in french about PIC development for beginners (part 1 is a 2 led blinker, part 2 will be a servo tester and how to decode servo signals). if necessary a new thread could be started about these PIC topics.
I will come back with a short description of PIC programming ("burning").
My documents, along with other RC-related PIC projects (FMS PIC cable) and also softwares to look at your transmitter settings in real time or record a flight, (these older docs exist in english or are bilingual) can be found at My club's website under 'Articles'. look for PIC, joystick, (simple)PCM.

About PIC procurement, I do not have info for the States, but in Belgium, I use MB Tronics Brussel
Look at 'Produits' -> 'Electronique'

I think more model hobbyist should benefit from PIC advantages, and "specialists" should be identified in the clubs.

About the 'music': this is beta-version only, tests are done to determine the best frequencies to find a plane from the greater distance.

Brussels Belgium
Last edited by Phildc; Jul 14, 2004 at 04:07 AM. Reason: rem about music
Jul 14, 2004, 04:27 AM
Registered User

PIC microcontroller programming - howto

Here a short summary of programming a small PIC:
- Get a programmer, e.g. PICSTART-Plus from Microchip, or other
- Install MPLAB IDE soft that comes with it or that you find on Internet
-Connect the programmer to the PC
- In IDE, ->File ->Import -> the .hex file to burn into the PIC
- In IDE -> Enable programmer
- You see the microcode to burn. If needed check parameters
-Install the PIC in the programmer socket
-Do VERIFY if you want
- Take the PIC and mount it
-You are ready for testing
You will need: a multimeter,
and an oscilloscope: see a virtual PC scope, using the audio input:

With IDE,and without a programmer , you can learn PIC programming,
and test by emulation on your PC (ref my tutorials in prev append)


Brussels Belgium

See Articles for software and harware at JDM-Nivelles Model Air Club
Jul 14, 2004, 05:11 AM
Registered User

Modifying the Audbeac code (music) in absolute

For those who want to exercise in 'absolute':

Modifying the Audbeac code (music) in absolute
In the code in memory, you will find two sequences of CALL instructions
that look like 2xxx where xxx is the address of the NOTE routine:
0D8 for F
0DE for A
0E4 for C
0EA for F-high
105 for a wait
These calls implement the (simple) music.
You can also replace an unnecessary CALL with a NOP (no-operation) 0000.
Sorry not all notes are implemented in this small prog.

BTW, just saw a 'PIC key and multichip... ' in same forum that I must go read

==> About thread 'PIC Key and multichip... <==

Last edited by Phildc; Jul 14, 2004 at 05:18 AM. Reason: have read PIC Key and multichip...
Jul 14, 2004, 09:21 AM
Registered User
Thanks Phillippe,
At least now I have a small understanging of how it works.
Sounds like a fun project. I think I found a place where I can buy the PICs
can you tell me what kind of Peizo you use, such as what model and manufacturer.
Thanks again

Jul 14, 2004, 09:51 AM
Registered User

Piezo type

I have no identifier for my piezo's.
Just a simple piezo (a quartz between two metallis sheets, with 2 wires one on each side, and probably a plastic housing), costs 50 Eurocents here.
You must make sure that it is not an electronic one with an oscillator, that works from a DC source. Here it is the PIC that creates gives the frequency to make the quartz oscillate, producing the sound.

'Articles' at my club's website
Jul 15, 2004, 06:25 AM
Registered User

New version - Higher tones

(not yet the PCM version)

Telephone -style sound, higher range.

Ask for the .hex file to test if you want, by priv.msg.