What you're wanting though is a combo of the lipo protection device -and- an alarm.

Still busy working on the low-ohms-meter. The displays for it are on the way along with the new ADC chip (nice 16 bit, dual channel unit).

Paul.

Paul, yes thats what we need, I will give you a reminder down the track a bit. I think it would be a big hit.

Tony

I'm hoping this week that the PCB for the prototype low-ohms-meter arrives. Everything else is here for the actual electronics aspect, once it's built I can look at casing and connector options.

Personally I'm quite excited about the LOM because it's not only a good tool for checking looms/wires/motors but it's also going to be the first project using these new 8x2 LCD panels, which I hope to later use on the remote volts/current alarm systems too... and many others.

There was a huge expenditure of budget this week as well... buying up thousands of regulators and MOSFETs in an effort to try and ride out the next AUD crash/dip... if it comes.

Here's a couple of pictures of the LOM, the final device will be encased properly and have a set of sockets for the 4-wire leads as well as battery compartment for a 9V cell etc.

The LOM finally came to fruitation tonight, showing its first set of real-life measurements.

I've got some adjustments to make to the design but otherwise things are great.

The range is 1~5000mR which should cover most demands.

I've moved the LOM development over to its own thread now, since it's becoming a commercial product and is out of the "throw ideas around" phase.

http://www.rcgroups.com/forums/showthread.php?t=1147776

Another new idea... well, more of a ramp up of an existing idea.

Take a PLD-LMA-LVA and encase it into something a lot tougher with a battery and put a louder alarm on it (running off 2S lipo would help a lot there).

Now, before everyone worries about the 2S lipo, consider that if it's all packed in foam etc it'd be quite safe, esp if it's packed in a tough PVC shell or similar.

The key features I want are ;

1. Survivability
2. LOUDNESS

Paul.

Found some moderately small but tough cases for the high-survivability LMA, I also have some fairly loud piezo buzzers to install.

The next trick is the battery, because a 2S lipo would be great for driving the piezo, however if we're just plugging into the 5V receiver power rails, it'll never have a charge source (unless you permit external charging, which adds complexity).

A possible alternative is a normal small 4-cell NiMH pack, though it's a lot more weight and they're now more expensive than a single Li cell + charge-manager. Right now I have already been using single-cell lipos + charge manager chip with good success off 5V systems.

Paul

Paul since you are using a micro, is it smart enough and have enough output capacity to switch between parallel and series on the cells? Parallel to charge off the Rx rail, series to drive the buzzer.

Just a thought if you wanted no extra components and simplicity.

John

G'day John,

Well, in reality it'd just be 'simpler' to make a booster circuit (switched capacitor would provide enough power) to drive the piezo buzzer off the single lipo cell rather than trying to do the parallel/series thing (especially since with most 2S packs you can't really run it in parallel due to the internal lipo cell connections).

Paul.

I assumed that would be the case and that you would have to use two single cells making the whole thing too much hassle. The boost charge IC's seem the way to go but I guess we trip over the cost/complexity bogie again.

Ah dear, how complex it is to be simple.

Well, if we use a switched capacitor booster arrangement it's not too complex (no inductors or diodes etc) but then you have to use a piezo because otherwise a normal magnetic buzzer will draw too much power (10mA vs 100mA).

Paul, is the rechargeability vital in this app?

The A23 12V alkalines they use in car alarm remotes etc weigh 8g and have a rated 65mAh capacity to a 6V end point. They are actually 8x 1.5 volt button type watch batteries I think. Cost <$3.

12V @10mA is a pretty loud no fuss piezo and would last quite a time as a LMA or LVA. No idea if this is feasable or not.

J

John,

My worry would be people not replacing the battery when required, only to find when they need it, it's no longer carrying any power.

Paul.

Paul, fair point .. but... before you dismiss it have a look at the discharge curve attached.

The AR23 is 8 of these things I'm pretty sure.

Flashing a Low voltage warning or beeping when there is only 75% capacity left is what micros are good at I thought??? Shelf life (self discharge) is pretty good too. Just replace every flying season.

John