I have a "crash beeper" from my LHS. Ive used it on my old 72mhz tx/rx. In the event of a crash...after 1 minute of inactivity from the tx or signal loss, the beeper goes off nice and loud so we can trace where it went. Well now that ive switched to 2.4....it doesnt seem to work the same. Anyone have any experience with making these things work on 2.4ghz. Would we have to plug it into a channel and activate with a switch? If so how do I that?

To use one of these on 2.4GHz (or on any set with fail safe that sets and holds servo in a predetermined position on failure of receipt of signal) it must be one that responds to a change in pulse width.  If you have fail safe on the throttle for instance, and the alarm goes off on low pulse width (low throttle position on most setups) then it will go off if the throttle position is on low- - you do set the throttle for low on fail safe, right?.  Unfortunately, most of these devices go off with loss of pulsing, not change in pulse width.  Now, if you have fail safe (most 2.4GHz units do) you never get a loss of pulse width at the sensor as the fail safe keeps it going to the servos or anything plugged into a servo channel.

Yes it is on low.

Guess what you're telling me is im porbably S>O>L!

I'm using one (three actually, one per plane) of the NovaTech alarms... cheapy things (less than $20) that plug into the aileron channel and have the aileron plug into the alarm's output, with a Spektrum DX7 tx and Spektrum AR7000 or AR9000 rx's. The alarms aren't specifically for 2.4ghz, but I've had no problem with it, except for when I tried plugging two aileron servos (with a Y adapter) into the alarm's output and the ailerons went crazy when the engine was running. Problem disappeared when I put the Y adapter before the alarm and only used one servo on the output.

They also double as a low voltage alarm, but you've got to hold right aileron while turning the plane on to activate it, and 2.4 usually takes too bind for the low voltage trick to work. Oh well, at less than $20 it's cheap insurance.

I have a few lost plane beepers that I got from Tower. They are Hobbico Air Alert monitor/locators. These will beep if there is no activity on the servo channel it's plugged into within 1 minute or so. These should work with failsafe receivers as well. It also has a power-up beep and a low battery warning beep.

Thanks for posting. Ive tried the hobbico beepers before...IMO they are pretty weak - not loud enough.

I should have mentioned, if you want to use your existing beeper, you can probably pull or cut the signal wire off of your beeper connector, so it never sees a servo pulse signal. It will just start beeping a minute after you turn on your receiver (or power up your ESC), but it's a cheap fix if you don't mind it beeping all the time. You could also plug it into a regular battery switch and then plug the switch into one of the receiver channels. Just make sure there is no signal wire on the battery switch (the JR and Spektrum switch harnesses have a signal wire pass-through, but most others don't). That will allow you to switch power on to the beeper just before you take off, and it will start beeping a minute later, since it doesn't see any servo pulses.

Mine vent to the outside of the fus with a small hole for the speaker.. I think they are cheap insurance.

those only work in minor crashes..... if you go down in a blaze of glory theres a good chance the battery or receiver with be destroyed

Use this. Uses its own power and has a 300 foot range. Easily switched between plane with no connection to the electronics.

http://www.keyringer.com/

cool product