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About RobertoA109

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    RC-Cam Visitor

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  1. 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
  2. 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
  3. 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.
  4. 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
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