Lost model alarm activated by spare channel

[DennisRB]

I want to make a simple buzzer that can be activated by a spare auxiliary channel switch. I have a small loud piezio buzzer and I want to connect it to a servo lead from the receiver. I have no idea how the electrical system works. I assumed that flicking the switch would give my 4.8V between 2 of the 3 available servo wires, but I could not get this to happen when testing with a mutimeter. Any info on how to get this working would be great. Also any info on how the receiver and servos talk to each other would be good too.

Cheers :)

[Malc C]

The three pins from the receiver supply power (+4.8v or +5.0v depending on if you use a rx battery or a BEC supply from the speed controller) and the PPM signal, you can't simply connect the buzzer across the signal and ground and turn it on or off from the TX. This is because the signal wire contains a pulse that is between 0.5ms and 2.0 ms long which is used to set the servo position, and you need something that will be turned on when this pulse is above or below the 1.5ms (mid stick) position.

There are several ways to do what you want, and they are all in effect the same, a simple radio controlled switch. For simplicity I use a PIC to control the searchlight on my helicopter from the TX. The module comprises of just three components, a 12F675 PIC, resistor and lead to plug the thing into the receiver. There are several versions on the net but most require you to have access to a PIC programmer.

If you don't have access to a PIC programmer then drop me an e-mail ( malcolm.crabbe@ntlworld.com ) and I'll we'll sort something out..

[slipstick]

If you're not into PIC programming the easiest versions use an old-fashioned 555 IC. See http://www.uoguelph.ca/~antoon/gadgets/gadgets.htm for several examples e.g. "Crashed Plane Locator" or, if you really want to "flick a switch" either R/C Switch will work.

However most Lost Plane locators work by detecting that the R/C signal is no longer being transmitted. You can connect to any channel, even one that also has a servo connected (with a Y-lead). You just switch the Tx OFF to start the buzzer.

Steve

[Malc C]

Yup, the site Steve has suggested has lots of useful non PIC related projects :) The NE-555 based "Crashed Model Beacon" would be the ideal CCt, but do read the notes about connecting a 9V battery.. you wouldn't want to blow your RX

[Mr.RC-CAM]

Are you sure you want to activate it by a spare channel? How about one that is activated when the Tx is off? If so, then a three component PIC based lost model alarm is discussed here: http://www.rcgroups.com/forums/showthread.php?t=278905

If it needs to be channel activated, then the PANCAM project has an Aux on/off function for this sort of application. It is also PIC based: http://www.rc-cam.com/pancam.htm

RC-CAM

[DennisRB]

Thanks guys :)

I like the LoMA: Worlds Simplest Lost Model Alarm. Its so small. http://www.rc-cam.com/lma.htm I would have no trouble building it, but I don't have a pic programer. How do they work? If I find someone with a PIC programer, what info would I need to give them to burn it? Would I just give them the correct software file?

[Malc C]

You can either buy yourself a PIC programmer (from as little as $12USD) and a 12C508 / 509 PIC (about $2USD), then download the HEX code and program the PIC yourself. Or if you have a friend with a programmer then simply point them to the URL and let them download the HEX and burn a PIC for you. Or drop Mr RC-CAM a PM and ask how much a pre-programmed PIC would be shipped to Australia.

[Malc C]

Some more CCts for you to consider

http://www.ncws.com/rcrock/locator.htm

http://www.ncws.com/rcrock/locator2.htm

[DennisRB]

Thanks Malc, I think I will look into making a PIC programmer.

[DennisRB]

Something like this?



https://secure2.vivid-design.com.au/jaycar/productView.asp?ID=KC5367&CATID=&keywords=pic+programmer&SPECIAL=&form=KEYWORD&ProdCodeOnly=&Keyword1=&Keyword2=&pageNumber=&priceMin=&priceMax=&SUBCATID=

[Malc C]

Looks good.. There are loads of kits available, the only limitation on that kit is that it will only support PICs up to 18pin, and as some of the stuff that cropps up on this message board uses PICs of 28 pin or more you would find you're missing out.

http://www.sparkfun.com/shop/images/114.jpg

I use a commercial version of the JDM programmer
from Spark Fun (http://www.sparkfun.com/shop/index.php?shop=1&cart=109242&cat=3&) this will handle most of the current PICs on the market in DIL format up to 40 pin.

Given the strength of the £ vs $ it cost less to purchase it via paypal from Spark Fun and ship it to the UK than to buy it from the UK agent !!

[DennisRB]

Thanks again Malc, but I will give it a miss for now becuase Gedaso has been kind enough to offer to burn me some PICs.


With the LoMA http://www.rc-cam.com/lma.htm Can this be plugged into any spare channel so I don't need to buy a Y lead?

[Malc C]

"Can this be plugged into any spare channel "

would of thought so...

[slipstick]

Can this be plugged into any spare channel
To be picky it should work in any channel that your transmitter is transmitting. If you had an 8-channel Rx and only a 6-channel Tx I don't think it would work in Ch7 & 8 because it detects the loss of signal and those channels never have a signal to lose ;).

Steve

[DennisRB]

Sweet, so I should be fine with a 6 channel TX transmitting to a 7 channel receiver as long I don't use plug it into the 7th channel (the plane only uses 2 channels, its a NCFM moth slope soarer)

[Mick Molloy]

Thanks guys :)

I like the LoMA: Worlds Simplest Lost Model Alarm. Its so small. http://www.rc-cam.com/lma.htm I would have no trouble building it, but I don't have a pic programer. How do they work? If I find someone with a PIC programer, what info would I need to give them to burn it? Would I just give them the correct software file?
If your still keen Dennis I have 20 pic chips already programmed.. I have made 4 and they work great BUT the buzzer I can find are not the loudest things around.

[kiwi_pete]

If your still keen Dennis I have 20 pic chips already programmed.. I have made 4 and they work great BUT the buzzer I can find are not the loudest things around.

I too have sucessfully made several of these LoMA's too although the buzzers could be a little louder IMHO.

I have another commercial LMA here with a different buzzer on it that is almost twice as loud as the std buzzer.
I have swapped this buzzer on to one of the LoMA's of MR RC-Cam's design and it makes a huge difference to the output sound!

The problem I have is I have not been able to source these buzzers here in New Zealand, but maybee one of you out there may be able to source some in your country and let me know where to get them from.

Details are as written on the sound end of the buzzer.
STAR2K QMB-111P.

Cheers all.