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Topic: High powering on the cheap (Read 3658 times) previous topic - next topic

sucotronic

I'm developing some kind of alarm using Arduino, glass break sensors and car horn. Here the problem is how to supply power to car horn, because it consumes up to 2A - 12VDC
I've found 2 cheap options:
1st option: use a PC power supply, it cost about 12? new
2nd option: use a laptop supply, in DX you can find a 12V-3A by 9$ and you will also need the cable cord, 3,5$ more

The first option is easy available in every pc shop, also is very powerful (up to 15A), but it's bulky and noisy. The second option has a lot of lead time but is more smart and compact.

Hope this helps somebody in the future  :)

keeper63@cox.net

#1
Jun 23, 2010, 11:51 pm Last Edit: Jun 23, 2010, 11:51 pm by keeper63@cox.net Reason: 1
If this is in a car, why not just activate the car horn relay directly using a transistor buffer driver (horn runs on battery)?
I will not respond to Arduino help PM's from random forum users; if you have such a question, start a new topic thread.

sucotronic

The alarm is going to be installed  in a shop, so the only thing related with cars is the horn :P
Why I choose a car horn? cause it is cheap and can be driven by a simple transistor (a TIP120 in my case).

keeper63@cox.net

Gotcha - makes sense, then...

:)
I will not respond to Arduino help PM's from random forum users; if you have such a question, start a new topic thread.

retrolefty

Well as long as you pulled the horn from a car, go ahead and pull it's battery and use that.  ;)

Tchnclfl

Quote
Well as long as you pulled the horn from a car, go ahead and pull it's battery and use that.


My thoughts exactly.

sucotronic

Quote
Well as long as you pulled the horn from a car, go ahead and pull it's battery and use that.


A car battery cost more than 30? and I also would need to add a car battery charger (~15? more), so isn't very cheap  ;)

GrooveFlotilla

Quote
A car battery cost more than 30?

But at least it will carry on working in the absence of mains electricity.
Some people are like Slinkies.

Not really good for anything, but they bring a smile to your face when pushed down the stairs.

borref

#8
Jun 24, 2010, 11:57 am Last Edit: Jun 24, 2010, 11:59 am by borref Reason: 1
If you really want to go cheap you could pick up a retired start battery. Although it can no longer be relied upon for starting your car (300/400 Amps) it could still serve as a standby "hornblower" and power your alarm system for another decade.

If you think it's too big an bulky, you could get a small MC battery. There is no need for a 15 Euro + charger. A small maintenance charger (500mA) is all you need even for a big start battery.

sucotronic

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A small maintenance charger (500mA) is all you need even for a big start battery.


The whole alarm has to be mounted in a small box and located on the ceiling of the shop, so,  could I choose a small 12v battery? Also the maintenance charger should be 12v rated, no?

kevinb1985

I have made done some work installing car equipment into houses.  Just get a cheap power inverter that puts out 12V.  Like a old flashlight charger.  Just check the amps.  Then you can us your arduino to trigger a relay?

borref

Nominal voltage for a fully charged 6-cell lead-acid battery is 12.7V and maintenance charge should ideally be regulated to between 13.5V and 13.8V. Many auto/MC supply stores (check also lawn mower outlets) carry small low cost wall-wart type chargers specifically for this purpose.

sucotronic

After talking with my friend he has confirmed that the battery isn't really a must, so I'm going to buy a cheap atx power supply  :D

sucotronic

Finally got the pc power supply for 12? and it delivers 14A 12V!!
Clic in the photo to see detail:



I could plug the arduino directly on the 5 line volt, but instead, I plugged directly the 12V line because of the peak consumption of the GSM module (it fails to call or send SMS when the power isn't enough).

The project in protoboard:


sucotronic

I've connected the 12V supplied by the power supply to the supply power of an arduino board. The problem is that when I swith on or off the kitchen fan of my house, the 5V power pin, whic I use for some analog sensors, bounces enough to give bad reads. Maybe I have try to add some cap or a coil :P

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