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hogboy01

Lost Model Alarm

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I think you will find that the buzzers that do not work with LoMA are simply the wrong type. Many 1205 type buzzers are missing the required internal drive oscillator (the buzzer you use must have an internal 4VDC-5VDC oscillator drive circuit). To test this, connect your buzzer directly to a 4.5V power source and verify you hear the loud buzzer tone. Also, measure the current to see that it is under 40mA. If these conditions are OK then it should work with LoMA.

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Hi Folks..

I'm having a bit of a problem with buzzers as well. I bought the following but for some reason, they don't seem to work until I discovered that the buzzers seem to be external drives:

http://www.maplin.co.uk/5vp-p-pcb-piezo-transducer-98112

I've tried sourcing others but can't quite put my hands on any. Off to have another hoke(look) but if anyone can shed light this side of pond I'd be grateful.

Regards

Declan

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I've noticed that if the part's catalog description only mentions "piezo transducer" then it usually requires an external drive. The ones with internal drives (which LoMA requires) usually mentions "buzzer" or "built-in oscillator" in their description. No doubt there are exceptions, so simply review the data sheet -- it will tell all the details.

No experience with it, but maybe this one will work:

http://www.maplin.co...indicator-98109

Edited by Mr.RC-Cam
Added maplin part number

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I've noticed that if the part's catalog description only mentions "piezo transducer" then it usually requires an external drive. The ones with internal drives (which LoMA requires) usually mentions "buzzer" or "built-in oscillator" in their description. No doubt there are exceptions, so simply review the data sheet -- it will tell all the details.

No experience with it, but maybe this one will work:

http://www.maplin.co...indicator-98109

Cheers. Many thanks

Just ordered some up. Don't know how I missed that one!!

Declan

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Hi,

Is is possible to convert the code to a Pic12F675?

I have several available here so it would be great to use them for this.

Thanks.

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Sorry, but I don't have a code version that would correctly compile for use on a '675.

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Well I tried to flash it but of course it didn't work. :(

Your version seemed easier to use and with some added cool features compared to others I've seen.

I just feel too lazy to go and do one. :)

Thanks anyway.

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Rc-CAM,

I was looking for a LMA project and then I run into your LMA.

I have some 1uF tantalum caps laying around, would it be possible use them instead of .1uF ?

Thanks,

Christian

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The recommended microcontroller decoupling caps are ceramic 0.01uF to 0.1uF.

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Thanks for your prompt reply.

Another question.

I have this buzzer with the following specs;

Oscillation Frequency (Hz) 3000 ± 500

Operating Voltage (Vdc) 1.5 ~ 30

Rated Voltage (Vdc) 12

Current Consumption (mA/max) 12 at Rated Voltage

Sound Pressure Level (dB/min) 80 at 30cm at Rated Voltage

My question is, I will use this LMA in a Plank and my battery pack is aroung 6V.

In my understand, I need to get 12V to have the louder db (as rated voltage) Is there a way to double my battery pack voltage (6v) to have a louder noise ?

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Operating Voltage (Vdc) 1.5 ~ 30

This tells me it is a piezo sounder and not a buzzer. The item you have requires an oscillator driver circuit whereas the one spec'd for the project will make noise simply by applying 5VDC to it.

Also, the PIC will be damaged by 6V so you need to add a 5V Voltage Regulator to the LoMA. Or perhaps drop the power supply voltage with a couple of series diodes in the Vcc supply.

But to answer your question, if you want to operate the buzzer on a voltage higher than 5V then you will need to add a transistor stage to drive it. I'll leave that part up to you.

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Check the link of the a buzzer a have

I don't have any experience with it so I can't say if it is a good choice. If it has an internal oscillator, works on 5V, and requires less than 40mA, then it should be fine.

FWIW, I have found that high frequency alert tones are not good choices for a lost model alarm. The higher frequency tones are often too directional and attenuate too quickly for this application. So try to select one that has the lowest possible audio tone frequency and highest sound pressure spec. The buzzer recommended in the project (http://products.cui....pdf?fileID=8247) works fine using ~2.3KHz and is quite loud). I don't recommend anything with a frequency that is much higher than that.

I have read the some diodes can do that, Do you agree ?

Diodes can be used to drop the power supply voltage. Be sure that the PIC never sees more than about 5.25V with a fully charged pack.

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Suddenly I found one buzzer in a old fax modem card (pci) I had.

dsc05810qd.jpg

Only thing I am in doubt, I applied power over the buzzer terminals and I could not hear a sound. Does it need the PIC in order to produce the frequencies or it should do a noise without the PIC ?

Edited by chrispaiva

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You must use a Buzzer with built in oscillator; The PIC does NOT provide the audio frequency. The correct buzzer choice for this project will be the type that makes the noise as soon as you apply 5VDC.

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Tomas,

I have finished my loma and it worked ! So happy ! :-P

Thanks for sharing your projects, I think this is the way to have knowledge spread around the world. You could help me miles away from your home. This is fantastic.

I am using a Turnigy 2.4 with Frsky Receivers. I could add the loma start using a switch perfectly setting the ATV from 0% to 125% after test I should have read the part to disable the glitch counter once I want to start noise from the switch.

My real problem now is to have the properly buzzer in hands, i did a search in the eletronics stores (a few) in my city, but I can only find piezzo buzzer. They do not sound loud.

In my previous post I sent a image of a magnetic buzzer took from a modem card.

Do you know a way to design a oscillator to feed this buzzer ?

I googled without sucess

Buzzer´s Specs

PAC-WT-1205-P

Rated Voltage 5

Drain Max.40mA

Coil Resistence 47±5ohm

dB - Min.87

Resonance 2400±200Hz

Operating Voltage 4-6V

Operating Temperature -20~+60

Weight(g) 2

Dimensions Ø12 x 9.8

Thanks in advanced !

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Glad to hear it is working. Sorry, but I don't have any circuit diagrams for the Piezo alarm.

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This is an old project that was developed for FM PPM receivers that do not output a valid servo pulse when the RF signal is lost.

Unfortunately your FrSky receiver has failsafe detection built into it. The FrSky is designed to produce artificial servo signals when RF control is lost. So it is not compatible with my published design.

The green LED on your receiver turns off when the RF signal is lost. Maybe you can create a circuit that monitors the green LED drive signal and have it control a buzzer. I don't have any details on how to do that, so it will need to be your own DiY project.

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