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dc812

LMA @ > 100% rates

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RC CAM;

I notice on a LMA project that when I put the LMA on a channel that was set up with rates >100%, that I got a alarm at one end of the throws. You mention this in the speacial project instructions not to place on a channel with rate <=100%, but as always, I am curious if the value of the cap could be adjusted to expand the non-alarm range, or is it software controlled?

Thanks in advance for you help and great projects....you have saved many planes from being lost!

DC

Edited by dc812

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Triggering the lost model alarm on >100% is a feature. This allows rx's with failsafe to be setup to trigger it. It is hard coded in the software.

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Hello, I'm writting from Spain, my name is Juan Carlos, and I teach technology to 14-16 year old students. I have maiden one of your LoMA, it is my firts time PIC programming. I made the programmer, and I burned the information.

You say to check that there is no shortcut.

I measure with the tester and I have 1680 ohms between + and -. I'm using a 1 microFarad tantalum capacitor, is this ok?

When I was burning the PIC i got a message: something like that there is no .... whether I wanted to use the default one. I said no. but I'm not shure if I had to say yes.

when I try it, it sounds all the time, so I disconect it quickly just incase anything burns.

thanks

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the message was "(NO OSCILLAROR CALIBRATION FOUND) DO u wnat to use value from file (0000h) instead" what do I've to do? yes or not. I pressed NO. but I'm not shure what do I've to do. Can anyone that has succeded tell me how has he done it?

Between + and - I have 1680 Ohms.

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thank you very much for your web and your proyects.

I have at last maked to work the LMA. I've though one question. I read the content of the pic , a 12C508A and it is not exactly the same as the .hex file, but it works. Is this ok? As you can see it is the first time I have programed a pic or anything similar.

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You are welcome, thanks for the kind feedback.

Hi, I've a question. is it posible to program the 12C508A in a diferent way? Is it posible to make it blip in a empty channnel when say for example you put full throtle?

thanks.

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Sure, software could be designed to do that. But, it is not a feature I plan to put in LoMA.

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Hi RC-CAM,

I have searched on the web quite a lot to find a Lost Model Alarm that

incorporates all features one could need in case the "landing" occurred

somewhere around, in the corn field or down the mountain.

I landed in your website. That was really good luck.

I discovered then that the right name for this wonderful piece of

jewelery was LoMA!

So first of all thank you very much for sharing it with other

r/c modelers around the globe and for providing such a good technical support.

As it is right now, your LoMA has everything I was looking for.

Really great job. The power save feature is just brilliant.

I have verified that my radio X-3810 (retrofitted with JETI Duplex 2.4GHz Tx module

and JETI Duplex 2.4GHz R8 receiver) is capable of generating pulses long enough

to activate the LoMA when in Fail Safe and it should be fine:

ATV +150% ==> 2.09ms (max)

ATV -150% ==> 0.9ms (min)

So I am ready to build 6 of the to equip all my models with it.

I would have only one small wish, to add a backup LiPo battery

(see attached schematics) with a schottky diode.

This because I noticed that in all crashes or very hard landings

the big LiPo battery pack flies away and disconnect itself from the ESC.

If the LoMA is connected to a spare channel of the receiver,

after the crash it would remain unpowered.

The idea to add a tiny LiPo battery to solve this potential problem.

LiPo fully charged 4.2V, empty 3.6V

The schottky diode has 0.4V fwd voltage

This would mean that the LoMA will have +5V (BEC) in normal conditions

and between 3.8V and 3.2V in case of a crash or a hard landing.

I have searched in your forum and I did not found similar requests

or questions. If there was one then I apologize.

Do you think that the attached schematics could work?

Is there a better way of adding a backup battery?

I have foreseen a switch, to turn the LoMA off when not in flight

(hangar or charging), and a connector to charge the LiPO battery.

RC-CAM, thank you once again for sharing your projects with the rest of the world!

Thank you in advance and ciao. Roberto

post-5994-127358344359_thumb.jpg

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I think you will need a second diode on your" V+ BEC" power input. That is because if the main battery is lost, the little LiPO you added would power the entire R/C system and be quickly discharged. A second diode would prevent that.

Also, the buzzer's alert tone might be too quiet at the lower LiPO voltage. The best thing to do is build a prototype and see how well it works for you. Please report back on what you find.

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I think you will need a second diode on your" V+ BEC" power input. That is because if the main battery is lost, the little LiPO you added would power the entire R/C system and be quickly discharged. A second diode would prevent that.

Also, the buzzer's alert tone might be too quiet at the lower LiPO voltage. The best thing to do is build a prototype and see how well it works for you. Please report back on what you find.

Hi Mr. RC-CAM,

thank you for your fast reply.

I will build a prototype next week and for sure I will report back on if it works or not.

I will try to test different buzzers to see if there is one that is still loud enough even

at low voltages.

Ciao, Roberto.

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Hi Mr. RC-CAM,

I finally managed to get a PIC Programmer that can program the PIC12C508A.

It is an old programmer board (PIC-01A) that works with WinPIC.

I bought 10 PICs in the local electronics shop (4.40Euros each!!!!).

The first 2 went bad but then the remaining 8 were successfully programmed

with the HEX file and are all working fine with the standard schematics.

I have tested the variant with the 2 schottky diodes (thanks for the correction)

and a variable power supply from 5.0V down to 3.3V

It works fine for me. It is true that the buzzer is not so loud at low voltage

but I hope that it will be still sufficient to be able to locate the lost model.

The buzzer I have found is a MEB-12C-5 that works with 3.0-6.0V

With 3.3V supply voltage the buzzer is still loud.

Unfortunately I have no instrumentation to quantify the sound pressure level.

So I plan to build all of them in this variant with twin buzzer to be sure

that when the LiPo is low the alarm is well audible in all directions.

Green light to build them all?

Thank you in advance for your comments.

Ciao, Roberto

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post-5994-127529116177_thumb.jpg

Edited by RobertoA109

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Thank for the report that it works for you. If you use twin buzzers then the total buzzer current should not exceed about 70mA under all operating voltages.

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Thank for the report that it works for you. If you use twin buzzers then the total buzzer current should not exceed about 70mA under all operating voltages.

Mr.RC-Cam,

I have finalized the assembly of the LoMA with backup battery.

To protect the LiPo I have built the PIC, the capacitor and the schottky diodes on a pcb.

A shrink tube keeps everything together in case of severe crash.

I have now a doubt about the max current.

In the datasheet of the buzzers I have mounted (MEB-12C-5) the specified average current at 5Vdc is 25mA.

There is a s well a driving circuit diagram where Icmax is 100mA???

I would like to check how much current the buzzers are sinking but how?

Shunt + oscilloscope?

Thank you in advance for your help.

Roberto

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post-5994-127529245752_thumb.jpg

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Just measure the current with a multimeter. If more than about 50mA average then a buffer transistor is probably needed.

Edited by Mr.RC-Cam

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RC CAM;

I notice on a LMA project that when I put the LMA on a channel that was set up with rates >100%, that I got a alarm at one end of the throws. You mention this in the speacial project instructions not to place on a channel with rate <=100%, but as always, I am curious if the value of the cap could be adjusted to expand the non-alarm range, or is it software controlled?

Thanks in advance for you help and great projects....you have saved many planes from being lost!

DC

Well, I have purchase a new Aurora 9 radio since this post, and have used the fail safe feature of the RC-CAM LMA to my advantage. On the A9, you can program the EPA of any of the channels to 140% which will set off the LM alarm. So I have the LMA on a switch so I can activate the alarm at will. Additionally, I have set the LMA channel to go to 140% during a fail-safe condition, so if I were to loose radio connect, it will still activate the alarm.

These LMA are fantastic, and very versatile.

Cheers!

DC

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