How to connect Arduino to car electric system (12V) ?

I don’t want to connect it through lighter connector, I want to throw a dedicated wire and make it hidden.

I heard that voltage regulator is needed for this.

Will this work:
http://www.dfrobot.com/index.php?route=product/product&filter_name=voltage%20regulator&product_id=584#.UfD8U6zpzto

What will happen if car voltage will be lower than 12V?

And if not this , what else do I need to connect arduino to car system?

No, that thing is used to power 12 volts devices in 24 volts systems like trucks (lorry's, big rigs) use.

You can use 12 volts as a power supply to your Arduino. It depends on what you're going to do with it. But in your car the power fluctuates an can get up to 14 volts, which might be too steep for the power supply on your Arduino (what type is your Arduino ?). If you're uncomfortable with 12 volts powering your Arduino, you could use one of these real cheap USB chargers. They often offer 1A current at 5 volts. You'd have to hack it a bit if you don't want to use it in the lighter socket.

Get an lm7812 and heat sink to keep the voltage below 12vdc because I've read the arduino acts slightly funky after 12vdc... You can get both at radioshack, they are in the voltage regulator drawer and they cost like $3. Attach the positve to the vcc pin and the negative to ground. Or use the power connector, but make sure you get the polarity right.

if you are wiring directly to the battery throw an inline fuse close to the battery connection to protect the wire that you use.

Hope that helps

A 78xx needs an input voltage that is 2.0 volts over the output voltage. Else the output will be unstable.

So if you go for this, try a 7810 or a 7809 (last will probably be better available). And just the regulator doesn't do the job well. Also use some capacitors: 100 nF at the input and at the output, and 100µF at the output. The 100 µF (micro Farad)is not calculated by any means, but is often used. If you know the total current of your setup, you can calculate this one.

Will the arduino be running while the auto is off, or just while engine is running? While running voltage will get as high as 14.8volts. How many current hungry devices will be drawing from the arduino (relays, etc)?

14.8 volts is a bit high to send into Vin with any current usage. If you are not using much current it may be OK. Otherwise, I would put a voltage regulator to drop the 14.8 down to about 7 volts, to feed to the arduino. Makes for a much happier baby.

What boards are you driving from the arduino?

good luck Jack

jackwp: Will the arduino be running while the auto is off, or just while engine is running? While running voltage will get as high as 14.8volts. How many current hungry devices will be drawing from the arduino (relays, etc)?

14.8 volts is a bit high to send into Vin with any current usage. If you are not using much current it may be OK. Otherwise, I would put a voltage regulator to drop the 14.8 down to about 7 volts, to feed to the arduino. Makes for a much happier baby.

What boards are you driving from the arduino?

good luck Jack

There'll be gps / gprs shield from dfrobot, they recommend 9V external power supply.

Where can I get this voltage regulator, that can input 12-15V from car (both engine running and not running, and maybe less than 12V when battery is low) and give stable output of 9V ?

Anywhere electronics are sold. Because 15 volts to 9 volts means quite a lot of the energy has to be "burned", you also need to mount the device on a heat sink.

If you like to get a finished product instead of making one, dfrobot which you already found have suitable power supplies too and the price of that seems reasonable. They also have a "power shield", which can be controlled and monitored by your Arduino (i'm not sure this unit will power the Arduino itself however). Its price is a bit higher.

have a look at this - http://ruggedcircuits.com/html/ruggeduino.html -

MAS3: dfrobot which you already found have suitable power supplies too and the price of that seems reasonable.

Yeah, I'm quite new to this electonics world, so I'm avoiding soldering.

But I can't see heat sink on this converter?

robtillaart: have a look at this - http://ruggedcircuits.com/html/ruggeduino.html -

Very interesting option, I'll consider it, thanks!

[quote author=Sly_G link] But I can't see heat sink on this converter? [/quote]

That's because this converter has an other mode of operation.

The 78xx burns power so the device you are powering it with has just enough left it needs. Burning means it gets hot, and you have to put the heat somewhere. So that's where the heat sink comes in.

The other converter essentially switches the power supply on and off again in a high rate, and filters it so that a dc power can be output. It doesn't burn the excess power so it will not get that hot. It will also be much more efficient because of that.

I wouldn’t use the Ruggeduino if you are new to the arduino game. It is great, but has limitations that you need to overcome with electronic skills. I had issues using real time clocks with the ruggeduino. I tried a couple fixes before I decided to put the ruggeduino on the back burner… I love the idea, I just don’t have the time to figure out the nuances of a different device, and I’d hate to send a beginner down the same path.

Go to radioshack, find the voltage regulators, and teach yourself to solder… It’s easy. Make sure you grab the heat sink as well. They are usually with the blank circuit boards…

As for the 7812 needing atleast 2 volts over its specified output to work properly, I’ve never had a problem with that… Even if it only outputs 9vdc because of a low input voltage, the arduino works fine…I guess I just use it because radio shack always has it, and it’s right down the road. Although you make a good point, and if there are 7809s around, I suppose it’s a better solution, except it might get a little hotter than the 7812… right?

I’m soldering these up as we speak for temperature data loggers that work of 12vdc solar… (it’s usally hang around 14vdc).

Better that a 7809 gets warmer than the voltage regulator on the Arduino.

I had a ZX-81, one common fix for the overheating problem (caused entirely by the 7805 inside the case) was to replace the badly filtered 12V with a well-filtered and solidly regulated 8V supply.

No radioshacks in Moscow, Russia. I can try online stores.

Is this 7809 thingy something like this http://ru.mouser.com/ProductDetail/Fairchild-Semiconductor/LM7809CT/?qs=sGAEpiMZZMtUqDgmOWBjgC5jv%252bsRCBsGpR4JL8812Nc%3d

This tiny box really can regulate output voltage when input is jumping around? Wow. Kind of magic.

Yes, that is it, and yes, it is the magic smoke inside that does it. Don't let it out! ;')

The circuit inside is something like this:

It is a good idea to connect a diode across the regulator like this, so that when power is shut off, a reverse voltage is not applied across the voltage regulator:

C2 in that circuit should be a tantalum or low ESR aluminum electrolytic capacitor of between 1uF and 10uF. C1 should probably be two capacitors, a 0.1uF ceramic and a 1000uF aluminum electrolytic. Cars are very noisy, electrically.

Seems the forum can’t handle GIF images very well

Whoa! Sorry about that, my browser shrunk them when I looked at them originally.

Ctrl-scroll wheel to shrink them, I guess.

LOL magic smoke... I've definitely let some of that.

Not to drag this on forever, but I just wanted to say I never add all the other components. You just need to look up the pin out for an 7812 or 7809 and hook it up, it'll work fine. Definitely don't stress about the other stuff, especially if you don't even know how to solder. It takes me like 2 minutes to hook one of these up.

http://compare.ebay.com/like/110714791828?var=lv<yp=AllFixedPriceItemTypes&var=sbar

When looking at the front

left leg is your input voltage center leg is your negative, solder two wires to that leg (one from power source one to the arduino) right leg is your output voltage for the arduino

I personally would use the 7812 because I read somewhere the closer you can get to 12vdc without going over 12vdc the better, the 7809 will work fine too though.

Good Luck and don't forget the heat sink. They get hot...

We just had a thread here where someone was using a linear regulator without the capacitor on the Out side, and it was breaking into oscillation under some loads and getting very hot.

IMHO, not worth saving 50 cents. It helps the transient response, too.

captainhooyah: LOL magic smoke... I've definitely let some of that.

Not to drag this on forever, but I just wanted to say I never add all the other components. You just need to look up the pin out for an 7812 or 7809 and hook it up, it'll work fine. Definitely don't stress about the other stuff, especially if you don't even know how to solder. It takes me like 2 minutes to hook one of these up.

http://compare.ebay.com/like/110714791828?var=lv<yp=AllFixedPriceItemTypes&var=sbar

When looking at the front

left leg is your input voltage center leg is your negative, solder two wires to that leg (one from power source one to the arduino) right leg is your output voltage for the arduino

I personally would use the 7812 because I read somewhere the closer you can get to 12vdc without going over 12vdc the better, the 7809 will work fine too though.

Good Luck and don't forget the heat sink. They get hot...

"the other stuff" (capacitors) is not ther only to give your board a better look, it really improves the regulation. Even if, for your use, it works without it, it will work better with it.

Not all we can read "somewhere" is truth ;) There are 2 reasons why I wouldn't use a 7812 : - if will only provide a well regulated output when the battery is 14V and over. Most of the time, the battery will be a little under 14V, and the output will be unstable - the output of the arduino regulator is 5V, right ? 12-5 = 7V !! The shield needs 150-200mA (and more during startup) 7X0,2 = 1,4W --> the arduino reg. will be very hot . I think it is easier to put a heatsink on the external regulator. Using a 7809 or a 7808 allows to split the power, and with a heatsink, the 7808/9 will be OK.