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garnold
(@garnold)
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Joined: 1 year ago
Posts: 74
2020-09-15 2:11 am  

I recently built a pretty cool project that sounds an alarm when a rubber hose is compressed. I'm having some fun with mountain bikes and jumping distance HAHAHA!

The project came out great but I'd like to make it smaller. Currently I'm using a larger siren that I would like to shrink down. There is an Arduino Pro Mini in there and it's all run off of a 9v battery.

A lot of the piezo sirens I've found run off 12v. I'm trying to figure out how to run my Pro Mini and one of these sirens effectively. I've read that a 9v battery is good for testing but not really a good way to power a project since there is a lot of energy waste.

I guess some kind of lipo would be a better way to power the system correct? But if I go with a lipo I'd also have to figure out some kind of power protection system so the battery does not drain to low and it can be charged.

I'm also thinking I would have to figure out some way to step up the voltage to get to the level I want for the siren?

Could I please get some advice on how to power this project and how to power the alarm? 

Thank you!


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byron
(@byron)
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Joined: 1 year ago
Posts: 354
2020-09-15 11:43 am  

@garnold

A similar question came up a short while back, but I find it quite hard to find old posts with the search facilities on this site so I will post the link I posted last time which covers the monitoring of external batteries that powers an arduino (and other things like your foghorn 😀) and taking suitable action when a set battery voltage level is reached.

I hope this helps.


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garnold
(@garnold)
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Posts: 74
2020-09-15 1:04 pm  

Thank you very much for this and I'll look over the video.

What might also help me is to better understand how to decide what kind of battery power I need to run my project. How does one figure out how much juice they need to make their project run? I could just keep going with the 9v idea but I'd like to be a bit more efficient. Or, is running with a 9v not really that bad if the items you are running do not draw much power? How do you figure all this out?

 

 


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byron
(@byron)
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Joined: 1 year ago
Posts: 354
2020-09-15 3:54 pm  
Posted by: @garnold

How do you figure all this out?

I think you will find theres a lot of suck it and see, but maybe a rough way to calculate this to start with would be an ammeter on you main power source, 12v, 9v or whatever.  This power source will probably use a buck converter (maybe more than one) to reduce the voltages to you various components, arduino's etc.  Power everything up and observe what amps are being drawn. Then decide how long the battery should last, and then get a battery with an appropriate amp/hour rating.   This is very rough and ready, the amps drawn by your project will probably fluctuate.  Also battery powered projects often send the microcontroller into a sleep mode for a while to reduce power consumption which will further complicate the calculations.   I hope this is a 'starter for 10' answer for you, and other more knowledgeable electronic wizards will give better suggestions. 


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